let. - vol. 48 (2002) {t. - no. STROJNIŠKI VESTNIK JOURNAL OF MECHANICAL ENGINEERING strani - pages 417 - 470 ISSN 0039-2480 . StrojV . STJVAX cena 800 SIT 1. 2. 3. 4. 00 ¦* CO o inteza orodij apake po m zanesljivosti in za analizo ~love{ke metodi analize spoznavne napak analize -d--r-e- vesa odpovedi of Human-Error The Synthesis Analysis Using the Cognitive Reliability and Error Analysis Metho Analysis and Fault-Tree zviren kombiniran ve~fazni model me{alne faze eksplozije pare ------- An Original Combined Multiphas Model of the Steam-Explosion Premixing Phase imuliranje izotermnega QUEOS preskusa me{alne faze eksplozije pare Q08 ------- Simulation of the Isothermal QUEO Steam-Explosion Premixing Experiment Q08 pliv ra~unskega polmera obra~anja motorja pri obra~anju ------- The Impact of a Fixed Kinematic Turning Radius of a Tracked Vehi ine Power required in a Turn motorja pri ------- The Impact ter © Strojni{ki vestnik 48(2002)8,417 Mese~nik ISSN 0039-2480 © Journal of Mechanical Engineering 48(2002)8,417 Published monthly ISSN 0039-2480 Vsebina Contents Strojni{ki vestnik - Journal of Mechanical Engineering letnik - volume 48, (2002), {tevilka - number 8 Razprave Zupančič, J., Marn, J.: Sinteza orodij za analizo človeške napake po metodi analize spoznavne zanesljivosti in napak ter analize drevesa odpovedi 418 Leskovar, M., Mavko, B.: Izviren kombiniran večfazni model mešalne faze eksplozije pare 438 Leskovar, M., Mavko, B.: Simuliranje izotermnega QUEOS preskusa mešalne faze eksplozije pare Q08 449 Stojkovič, V., Mikulič, D.: Vpliv računskega polmera obračanja goseničnega vozila na potrebno moč motorja pri obračanju 459 Osebne vesti Navodila avtorjem 467 469 Papers Zupančič, J., Marn, J.: The Synthesis of Human-Error Analysis Using the Cognitive Reliability and Error Analysis Method and Fault-Tree Analysis Leskovar, M., Mavko, B.: An Original Combined Multiphase Model of the Steam-Explosion Premixing Phase Leskovar, M., Mavko, B.: Simulation of the Isothermal QUEOS Steam-Explosion Premixing Experiment Q08 Stojkovič, V., Mikulič, D.: The Impact of a Fixed Kinematic Turning Radius of a Tracked Vehicle on the Engine Power required in a Turn Personal Events Instructions for Authors stran 417 glTMDDC © Strojni{ki vestnik 48(2002)8,418-437 © Journal of Mechanical Engineering 48(2002)8,418-437 ISSN 0039-2480 ISSN 0039-2480 UDK 66.012.004.64:614.8 UDC 66.012.004.64:614.8 Izvirni znanstveni ~lanek (1.01) Original scientific paper (1.01) Sinteza orodij za analizo ~love{ke napake po metodi analize spoznavne zanesljivosti in napak ter analize drevesa odpovedi The Synthesis of Human-Error Analysis Using the Cognitive Reliability and Error Analysis Method and Fault-Tree Analysis Janja Zupan~i~ - Jure Marn V pričujočem prispevku je bila obravnavana sinteza orodij, ki so uporabljana za oceno človeških napak (analiza spoznavne zanesljivosti in napak - ASZN - CREAM) in tehničnih odpovedi (drevo napak) na tak način, da je moč dobljene rezultate smiselno primerjati. Sinteza je bila opravljena za obstoječo rektifikacijsko kolono. Predlagane in predstavljene so izboljšave na osnovi dobljenih rezultatov. © 2002 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: metode CREAM, verjetnost napak, verjetnost okvar, drevo odpovedi) In this paper we have looked at the synthesis of tools used for human-error analysis (Cognitive Reliability and Error Analysis Method - CREAM) and technical error or device error fault tree) in such a way that a comparison between the results is possible. The synthesis was performed for an existing rectification system (column). Possible improvements are shown and suggested. © 2002 Journal of Mechanical Engineering. All rights reserved. (Keywords: CREAM methods, human probability, failure probability, fault tree analysis) 0 UVOD Optimizacija procesov, povečevanje dobička, manjšanje stroškov, zlasti stroškov dela, so povzročili umik običajnih pripomočkov, ki so prispevali k zmanjšanju ali odpravi vplivov pomanjkljivega znanja. Na drugi strani je razvoj svetovno nevarnih sistemov za proizvodnjo energije in objektov procesne tehnike, zlasti s področja kemije, povzročil potrebo po manjšanju verjetnosti nezgod na človeštvu še sprejemljivo raven, ki se pogosto bliža frekvenci 1x105 dogodka na leto, kar prevedeno pomeni eno nezgodo v 100.000 letih obratovanja posameznega objekta. Za uporabnika ali operaterja pomeni taka verjetnost zanemarljivo tveganje. V tem prispevku želimo prikazati možnost povezave med metodologijo ovrednotenja verjetnosti napake kot človekovega prispevka k odpovedi zahtevnega procesnega sistema in metodologijo ovrednotenja verjetnosti okvare kot tehnološkega prispevka k odpovedi procesnega objekta. Prednost prikazane metode je v enakovredni obravnavi nezgod in okvar ter v številski oceni verjetnosti odpovedi zahtevnega procesnega sistema. Verjetnostna varnostna analiza na področju tehnoloških sistemov1 v procesnem strojništvu je dobro razvita. Na tem področju je tudi pri nas moč najti več prispevkov, ki sodijo v zakladnico svetovne 0 INTRODUCTION The optimization of processes, the increase of profit, and the decrease of costs, in particular labor costs, have resulted in an end to classical ways of decreasing or eliminating effects that occur due to a lack of knowledge. In addition, the evolution of globally dangerous systems for energy production and process engineering installations, in particular in the area of chemistry, caused the drive toward a lower accident probability that was at a level acceptable to the public, usually of the order of 1x 105, i.e. one accident in 100,000 years of operation for a particular installation. For both user and operator such a low frequency usually amounts to a negligible risk. This paper deals with the possibility of a connection between the methodology of the accident probability evaluation of the human contribution to the failure of a complex-process installation, on the one hand, and the methodology of the evaluation of the technological contribution to failure of the same installation. The advantage of the method presented below is in the transformation of both types of information into comparable quantities, and the better assessment of complex-process system failure. The probabilistic safety analysis of technological systems1 in process engineering is well established. There are several studies in this area available in Slovenian professional literature: works VBgfFMK stran 418 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis znanosti, zlasti deli Kožuha ([1] in [2]). Večje težave pa so pri opredelitvi vpliva, ki ga imajo na delovanje kompleksnih sistemov ljudje. V pričujočem prispevku zato poskušamo dvoje: ponoviti verjetnostno varnostno analizo odpovedi z uporabo analize dreves dogodkov, dobro znanih iz številnih del ([3] in [4]), najti je moč še številne druge avtorje in nadalje, to analizo nadgraditi z uporabo sodobne metodologije na področju analize vpliva človeških napak. Pri tem nimamo namena zadovoljiti zgolj z opisom mogočih posledic, temveč želimo vpliv človeških napak tudi številsko izraziti, s tem pa prepričati morebitne uporabnike2, da bi predstavljeno metodologijo pričeli rutinsko uporabljati za svoje redno delo. 1 TEORETIČNA IZHODIŠČA Človeške napake pomenijo 60 do 90 odstotkov vseh sistemskih napak.V zadnjih 40 letih se delež nezgod, katerih vzrok je človeška napaka, zvečuje. To ne pomeni, da povzročamo ljudje čedalje več napak, ampak da prihajajo s tehnološkim razvojem vedno bolj do izraza. Soodvisnost je prikazana na sliki 1 po [5]. Z uvajanjem sistemov nadzora kakovosti vse do sistema popolne kakovosti namreč prihaja do redkejših lomov strojev, človeška zanesljivost pa je ostala približno nespremenjena3. To spoznanje lahko spreminja žarišče dosedanjih verjetnostnih varnostnih analiz na področju zahtevnih tehnoloških sistemov iz analiz, ki so se zlasti ukvarjale z verjetnostjo odpovedi posameznega dela sistema, v analize, ki se ukvarjajo z verjetnostjo napačnih odločitev vpletenih na vseh stopnjah procesov (oz. organizacijski faktor). Poglobljena analiza zahtevnih tehnoloških sistemov such as Kožuh ([1] and [2]). However, it is harder to find such contributions in the area of human-error analysis effecting complex engineering systems. In this contribution we have tried to achieve two objectives: first, to repeat a well-established probabilistic safety analysis using the fault-tree-analysis method known from several contributions ([3] and [4]), and several other authors and second, to augment this analysis with a human-error analysis using modern methodology in this area. Further more, in addition to qualitatively describing possible consequences we have strived to quantify the effects of these errors, thereby convincing the users2 of this information to start using such a methodology in their day-to-day operations. 1THEORETICAL BACKGROUND Human errors represent 60-90% of all system failures. Over the past 40 years the ratio of accidents caused by human factors to all accidents has steadily increased. This does not mean that people are less careful, rather it means that technological progress is eliminating mechanical errors. This codependency was shown by [5], whose figure is reproduced as Figure 1. Modern quality systems such as Total Quality Management (TQM) have resulted in a reduction of mechanical failures, while human reliability has tended to stay constant unless influenced by training or other methods3. This conclusion can change the focus of to-date probabilistic safety analyses in the area of complex technological systems from analyses mainly dealing with the probability of failures to particular parts of a system to analyses dealing with the probability of erroneous decisions of all those involved in various levels of processes (the so-called organizational factor). The in-depth analysis of 1960 1965 1970 1975 1950 19S5 1990 1995 Sl. 1. Delež nezgod, katerih vzrok je človeška napaka [5] Fig. 1. Fraction of human-error-induced accidents [5] ^vmskmsmm 02-8 stran 419 |^BSSITIMIGC Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis tako še naprej ostaja v osti varnostnih analiz, zlasti na področju latentnih in zato premalo opazovanih napak [6]. Avtorja ugotavljava, da je bilo v začetku veliko zanimanje za tehnološko zanesljivost (v 70.), potem so spoznali, da je ključen človek (v 80.), in nato, da je pomembna organizacija (v 90 letih prejšnjega stoletja). V nadaljevanju je najprej opisan problem, nato pa prikazana uporaba metodologije drevesa odpovedi (znane tudi pod imenom drevo napak), zatem uporaba metode spoznavne (oz. miselne) zanesljivosti in analize napak [5] na sistemu rektifikacijske kolone in nazadnje sinteza obeh metod ter primerjava med verjetnostjo nezgode in okvare s predlogom odprave. 2 OPIS PROBLEMA Poglavitni namen dela je določitev verjetnosti tehnične (mehanske) in človeške napake rektifikacijskega sistema, katere posledica bi bil trenutni oziroma stalni izpust tekočinske mešanice. Obe vrsti izpusta bi bili iz vidika ekonomike procesa in parametrov okoljske varnosti nesprejemljivi, zato je treba določiti ne le verjetnost odpovedi temveč tudi posamezne vplivne parametre, ki na morebitno napako vplivajo. Številska vrednost prispevka napake posameznega vplivnega parametra, v okviru predpostavk, podaja tudi vrstni red, ki ga je smiselno upoštevati pri odpravi napak. Tako je moč v okviru prispevkov tehničnih napak ugotoviti potrebo po zamenjavi posameznih kritičnih delov in smiselno frekvenco preventivnih pregledov, v okviru prispevkov človeških napak pa tista področja, na katerih je primerno izvesti dodatno izobraževanje ljudi, ki so neposredno vpeti v proces obratovanje rektifikacijske kolone. Pri tem je smiselno poudariti še, da imata izobraževanje in trening omejitev in verjetnosti napake ne moremo poljubno zmanjšati [11]. Za določitev verjetnosti tehnične napake rektifikacijskega sistema je bila uporabljena metoda drevesa napak. Verjetnost človeške napake je bila vrednotena z osnovno in razširjeno metodo ASZN. Verjetnost človeške napake je bila vključena v drevo napak za trenutni in stalni izpust in hkrati opravljena analiza vpliva verjetnosti človeške napake na skupno verjetnost napake pri obeh izpustih. 2.1 Opis delovanja sistema V rektifikacijski koloni, osrednji napravi rektifikacijskega sistema, poteka postopek ločevanja zmesi aceton - izopropanol - voda na podlagi različnih hlapljivosti navzočih sestavin. Ločevanje komponent poteka pri temperaturah vrelišča, pri čemer slika 2 prikazuje shemo rektifikacijskega sistema, ki je sestavljen iz rektifikacijske kolone, uparjalnika in kondenzatorjev. ^BSfirTMlliC | stran 420 complex technological systems still remains at the cutting edge of safety analyses, in particular for latent and therefore not-enough-observed errors [6]. The authors note that interest has shifted from an initial interest in technological reliability (1970s) to human-error analysis (1980s), and finally to organizational aspects of reliability (1990s). The problem will be briefly discussed below, and this will be followed by the use of the methodology of failure-tree analysis, and then the use of [5] applied to the system of a rectification column, and finally the synthesis of both methods and a comparison between the probability of error and accident with a suggestion for system remedies. 2 PROBLEM DESCRIPTION The basic goal of this work is the quantification of technical (mechanical) and human error during the continuous operation of a rectification system that causes instantaneous and continuous releases of a fluid mixture. Both types of leaks are unacceptable from the viewpoint of the economy of the process and ecological safety parameters; therefore, not only the probability of failure needs to be assessed but also the important parameters influencing the failures. A quantitative assessment of a particular failure mode also forms the basis for the mitigation of the factors leading to this failure: first the parameters leading to the most probable failure mode need to be investigated, followed by the second most probable, etc. given that the damage to life, people, and property is similar. This methodology enables one to establish which parts of the machinery are most likely to fail and therefore schedule preventive maintenance; and which areas should be addressed when training people involved in the operation of the rectification system. At the same time it should be noted that the effects of education and training are limited and that the probability of human error cannot be lowered indefinitely [11]. Fault-tree analysis was used for the evaluation of the technical error of the rectification system. The probability of human error was assessed using the basic and extended CREAM method. Then, the probability of human error was included in the fault trees for instantaneous and continuous releases and analyses of human-error influence on the total probability for both cases was performed. 2.1 Description of system operation The process of separating acetone-isopropanol-water occurs within a rectification column forming the main part of a rectification system. The process is based on the different volatilities of the individual components. The separation occurs at the boiling temperatures of the components. The system is comprised of the rectification column, an evaporator and a condenser, and is shown in Fig. 2. Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis kondenzator, C1 condenser, C1 l=4 m, D=30 mm V5 X} ostanek brime vtok inlet Sl. 2. Shema rektifikacijskega sistema Fig. 2. Schematic of the rectification system S črpalko napajalno zmes doziramo s strani v kolono. Z merilnikom pretoka uravnavamo pretok napajalne zmesi. V koloni zmes ločujemo v lažje hlapni aceton in težje hlapno zmes izopropanol - voda. Ta se nabira na dnu kolone, kjer intenzivno vre. Za razvoj hlapov skrbi uparjalnik, skozi katerega kroži težje hlapna zmes. Hlapi iz uparjalnika se dvigujejo po koloni navzgor in na svoji poti prihajajo na površini polnil v stik s padajočo napajalno zmesjo. Zaradi intenzivnega stika med dvigajočimi hlapi in padajočo zmesjo pride do intenzivne toplotne in snovne izmenjave med njima. Iz padajoče zmesi se uparja del lažje hlapne komponente, iz dvigajočih hlapov kondenzira del težje hlapne komponente. Težje hlapljiva zmes se nabira na dnu kolone. Aceton se dviga proti vrhu kolone skozi refluksno glavo v kondenzator. V kondenzatorju aceton kondenzira. Nastali destilat se zbira v refluksni glavi kolone. Del destilata se kot refluks preliva nazaj v kolono, The mixture is introduced into the system using the pump. The flow into the system is adjusted in accordance with the flowmeter reading. Inside the column the mixture is separated into acetone, which boils at a low temperature, and a mixture of isopropanol and water. The latter accumulates at the bottom of the column, where it boils intensively. The vapors are primarily formed within the evaporator, through which the heavier mixture circulates. The vapors from the evaporator rise through the column and are brought into contact with the falling input mixture. Due to the intensive contact between both flows an intensive heat and mass transfer takes place. As a result, the most volatile compound evaporates while the heavier compounds condense and flow back to the bottom of the column. The acetone rises to the top of the column through the reflux head into the condenser. The acetone condenses inside the condenser. The resulting condensate accumulates in the reflux head of the column. Part of the liquid flows back into the column while gfin^OtJJIMISCSD 02-8 stran 421 |^BSSITIMIGC T 1 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis del pa odteka iz kolone skozi regulacijski ventil za uravnavanje refluksnega razmerja skozi hladilnik destilata v rezervoar. Pretok destilata uravnavamo z regulacijskim ventilom tako, da temperatura v glavi kolone ne naraste nad nastavljeno vrednost, ki je tik nad vreliščem acetona. Pretok težje hlapne zmesi iz dna kolone kot destilacijski preostanek krmilimo z odjemnim regulacijskim ventilom, tako da je nivo nespremenljiv. Temperatura vrelišča lažje hlapne sestavine - acetona je 56,5 oC, težje hlapne -izopropanola pa 80,3 do 82 °C. - Sestava vhodne zmesi: aceton (75 ut. %), izopropanol (15 ut. %), voda (10 ut. %). - Ciljna sestava destilata: aceton (95,0 ut. %), izopropanol (3,0 ut. %), voda (2,0 ut. %). - Sestava destilacijskega preostanka: aceton (največ 5,0 ut. %), izopropanol - voda (95,0 ut. %). Iz dolgoletnih izkušenj operaterja so v obratu, kjer obravnavana kolona deluje, postavili naslednje delovno pravilo: najmanj 95 ut. % acetona v destilatu je zagotovljeno s stalnim vzdrževanjem temperatur T =56-57 °C v refluksni glavi kolone in T =80 °C na dnu kolone. Dejavnosti operaterja pri pripravi, vklopu, obratovanju in izklopu rektifikacijske kolone so opisane v preglednici 3. 3 IDENTIFIKACIJA TEHNIČNIH ODPOVEDI IN ANALIZA Z METODO DREVESA ODPOVEDI V literaturi [7] je moč tehnične odpovedi razdeliti na tiste, ki imajo za posledico trenutni izpust (zaradi sesutja oziroma porušitve uparjalnika/kolone/ kondenzatorja, prelom cevi) in tiste, katerih posledica je stalni izpust (poškodba plašča uparjalnika/kolone/ kondenzatorja, poškodba cevi). To razdelitev smo upoštevali tudi v pričujočem prispevku. V nadaljevanju tako najprej identificiramo in analiziramo odpovedi s posledico trenutnega izpusta in nato odpovedi s posledico stalnega izpusta. Uporaba in izdelava drevesa odpovedi je dobro znana. Najti je moč več avtorjev, v konkretni analizi pa smo se naslonili na delo [8]. Izračun verjetnosti za vmesne in glavni dogodek so za vse primere izračunani s t.i. Booleanovo algebro: vezje ALI: lG=l1+l2-(l1xl2) • • • e vezje povezuje dva dogodka another part of the liquid flows from the column through the control valve enabling the control of the reflux ratio through the condensate cooler into the reservoir. The actual flow of the liquid is controlled in such a fashion that the temperature within the reflux head does not rise above a preset value that is just above the acetone’s boiling point. The flow of the heavier compound from the bottom of the column (bottom product) as well as the distillation bottom product is manipulated by the control valve in order to obtain an approximately constant level. The boiling point of the lighter compound, acetone, is 56.5°C, the boiling point of the heavier isopropanol is 80.3-82 °C. - The input fluid is comprised of acetone (75% w), isopropanol (15% w), and water (10% w). - The desired distillate contains acetone (95% w), isopropanol (3 % w), water (2% w) - The distillation bottom-product contains acetone (5% w max.), isopropanol-water (95% w) To achieve the best result the following rule has been established, based on several years’ worth of observation: a minimum of 95% w of acetone in the distillate is ensured with a constant temperature T=56-57 °C in the reflux head of the column and T =80 °C in the bottom of the column. The activities of the operator during preparation - turning on and turning off the rectification column - are described in Table 3. 3 IDENTIFICATION OF TECHNICAL FAILURES AND THE FAULT-TREE ANALYSIS The literature [7] distinguishes between technical failures that result in an instantaneous release as a result of evaporator, column, condenser, or tube failure, and technical failures that result in a continuous release (damage to the shell of the evaporator, column, condenser, or tube). This division was also used in this study. Below, we identify and analyze the failures that result in an instantaneous release, and then the failures that result in a continuous release. The use of a failure tree is well known. There are several authors who have explored this method in detail; however, this analysis was based on work by [8]. The computation of the probability for the top and intermediate events are calculated using the so-called Boolean algebra, as follows: OR gates: lG=l1+l2-(l1xl2) • • •if the gate connects two events l G=1-[(1-l1)x...x(1-ln )] ... če vezje povezuje n l G=1-[(1-l1)x...x(1-ln)] ...if the gate connects several dogodkov vezje IN: lG=l1xl2x...xl lx... verjetnost dogodka (2) (3). (n) events AND gates: lG=l1xl2x.. .xln lx ...probability of event (2) (3). Verjetnosti osnovnih dogodkov za rektifikacijski sistem ločevanja mešanice aceton-izopropanol - voda, ki smo jih povzeli po [7], so bile The probabilities of the top events for the rectification system for separating acetone-isopropanol-water were taken from [7] and adjusted VBgfFMK stran 422 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 1. Verjetnosti osnovnih dogodkov opisanega rektifikacijskega sistema Table 1. Basic events probability of described rectification system DOGODEK EVENT VERJETNOST DOGODKA PROBABILITY OF EVENT prelom napajalne cevi uparjalnika (D=90 mm, l=0,5 m) reboiler feed line rupture (D=90 mm. l=0.5 m) 1,3x10-7 /leto (year) puščanje napajalne cevi uparjalnika (D=90 mm, l=0,5 m) reboiler feed line leak (D=90 mm. l=0.5 m) 2,7x10-6 /leto (year) prelom napajalne cevi kolone (D=30 mm, l=4 m) column feed line rupture (D=30 mm. l=4 m) 3,5x10-6 /leto (year) puščanje napajalne cevi kolone (D=30 mm, l=4 m) column feed line leak (D=30 mm. l=4 m) 3,5x10-5 /leto (year) prelom odvodne cevi iz dna kolone (D=90 mm, l=1,3 m) column bottom discharge line rupture (D=90 mm. l=1.3 m) 3,4x10-7 /leto (year) puščanje odvodne cevi iz dna kolone (D=90 mm, l=1,3 m) column bottom discharge line leak (D=90 mm. l=1.3 m) 6,9x10-6 /leto (year) prelom odvodne cevi iz vrha kolone (D=30 mm, l=12 m) column top discharge line rupture (D=30 mm. l=12 m) 1,0x10-5 /leto (year) puščanje odvodne cevi iz vrha kolone (D=30 mm, l=12 m) column top discharge line leak (D=30 mm. l=12 m) 1,0x10-4 /leto (year) sesutje uparjalnika/kolone/kondenzatorja column/reboiler/condenser rupture 6,5x10-6 /leto (year) puščanje plašča uparjalnika/kolone/kondenzatorja column/reboiler/condenser shell leak 1,0x10-5 /leto (year) preračunane glede na dolžine dejanskih cevi in so prikazane so v preglednici 1. 3.1 Trenutni izpust Shema drevesa odpovedi za trenutni izpust je prikazana na sliki 3. Na vrhu je glavni dogodek (“top event”), katerega verjetnost ocenjujemo, pod njim pa tisti dogodki, ki na verjetnost odpovedi vplivajo. Z vezjem ALI poudarimo, da se dogodek (odpoved) nad vezjem ALI zgodi, če se zgodi katerikoli od dogodkov, ki jih vezje ALI povezujejo, z vezjem IN pa, da se dogodek nad vezjem IN zgodi, če se zgodijo vsi dogodki, ki so med seboj povezani z vezjem IN. Že ta del kaže, da rektifikacijski sistem ni v zadostni meri opremljen z varnostnimi sistemi, če seveda so verjetnosti odpovedi posameznega podsistema nesprejemljive, saj bo verjetnost odpovedi celotnega sistema kvečjemu višja od verjetnosti odpovedi posameznega podsistema. 3.2 Stalni izpust in rezultati analize drevesa odpovedi Shema drevesa odpovedi za stalni izpust je prikazana na sliki 4. Preglednica 2 kaže rezultate za verjetnost trenutnega in kontinuiranega izpusta v obeh primerih, izračunane z enačbama (1) in (2) za posamezne primere s slik 3 in 4. 4 IDENTIFIKACIJAČLOVEŠKIH NAPAK Z UPORABO OSNOVNE IN RAZŠIRJENJE METODE CREAM for the actual lengths of the pipes. The results are shown in Table 1. 3.1 Instantaneous release The failure-tree schematic for an instantaneous release is shown in Fig. 3. On the top there is an event, the probability of whhich one wishes to estimate. Below the top event there are events that influence the top event. An OR gate connects events where each event connected occurring causes the event above the gate to occur while an AND gate connects events where all events connected occurring causes the event above the gate to occur. The rare use of AND gates in the presented case shows that the rectification system is not sufficiently equipped with safety features (provided that failures of subsystems are not acceptable) as the probability of failure of the total system could only be higher than the probability of failure of a particular subsystem. 3.2 Continuous release and the results of the fault-tree analysis The fault-tree schematic for a continuous release is shown in Fig. 4. Table 2 shows results for the probability of instantaneous and continuous releases in both cases calculated using Eqs. (1) and (2) for the cases in Figs. 3 and 4. 4 IDENTIFICATION OF HUMAN ERRORS USING BASIC AND EXTENDED CREAM METHODS V nadaljevanju prikazujemo identifikacijo Below, we examine the identification of human človeških napak in njihovo analizo z uporabo errors and their analysis using the basic and extended stran 423 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis osnovne in razširjene metode ASZN, ki jo povzemamo po [5], in sicer najprej z osnovno metodo, ki jo dogradimo še z razširjeno metodo. 4.1 Analiza po osnovni metodi ASZN Osnovna metoda sestoji iz naslednjih treh stopenj: - opis naloge ali dela naloge, ki ju analiziramo in opravimo tako, da posamezno nalogo razčlenimo na njene sestavne dele, podobno kakor je to za verjetnost odpovedi, opravljeno z uporabo drevesa odpovedi (preglednica 3), - ocena splošnih pogojev dela4, pri čemer za vsakega od predstavljanih pogojev dela izberemo primerno vrednost (preglednica 4), - določitev verjetnega načina nadzora5 (preglednica 5). CREAM methodology by [5]. 4.1 Analysis using the basic CREAM method The basic method comprises the following three levels: - description of the task or part of the task subject to analysis which is performed by breaking down particular tasks into their components in a similar fashion as done with failures using the fault-tree analysis, Table 3, - assessment of common performance conditions4 where a suitable value for each of the conditions of work is selected, Table 4, - selection of probable control mode5 , Table 5. Preglednica 2. Rezultati analize za trenutni in stalni izpust Table 2. Results of analysis for instantaneous and continuous release NAPAKA FAILURE VERJETNOST NAPAKE - p PROBABILITY OF FAILURE - p trenutni izpust instantaneous release 4,6x10-5 stalni izpust continuous release 2,0x10-4 TRENUTNI IZPUST INSTANTANEOUS RELEASE izpust release Q napaka pri napa janju charging fail ure napaka pri uparjanju evaporation failure napaka pri ločevanju separation failure napaka pri kondenzaciji condensation failure vtok input prelom cevi line rupture uparjanje evaporation ločevanje separation TT kondenzacija condensation Q O 8,8x10"/mleto (myear) sesutje uparjalnika evaporator rupture prelom cevi line rupture U L-U sesutje kolone column rupture O 6,5 x 10/leto (year) prelom cevi line rupture sesutje kond. 1 conden. 1 rupture L-L C-1 O o o o 2,6 x 10/mleto (myear) 6,5 x 10/leto (year) 2,6 x 10/mleto (myear) 6,5 x 10/leto (year) prelom cevi line rupture L-C 2,6 x 10'/mleto (myear) sesutje kond. 2 conden. 2 rupture sesutje kond. 3 conden. 3 rupture O 6,5 x 1 0/leto (year) O 2,6 x 10'/mleto (myear) Sl. 3. Drevo napak - trenutni izpust Fig. 3. Fault tree – instantaneous release VBgfFMK stran 424 L-V K C-2 C-3 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis STALNI IZPUST CONTINUOUS RELEASE izpust release Q napaka pri napa janju napaka pri uparjanju charging fail ure evaporation failure vtok input uparjanje evaporation poškodba cevi line leak napaka pri ločevanju separation failure napaka pri kondenzaciji condensation failure O 8,8 x 10-7/mleto (myear) ločevanje separation P kondenzacija condensation Q pošk. plašča uparjalnika evaporator shell leak poškodba cevi line leak pošk. plašča kolone column shell leak poškodba cevi line leak pošk. pl. kond. 1 cond. 1 shell leak O 1,0 x 10-5/leto (year) O 5,3 * 10-6/mleto (myear) L-L* O O O 1,0 x 10-5/leto (year) 5,3 x 10-6/mleto (myear) 1,0 x10-5/leto (year) poškodba cevi line leak 5,3 x10-6/mleto (myear) pošk. pl. kond. 2 cond. 2 shell leak pošk. pl. kond. 3 cond. 3 shell leak O 1,0 x 10-5/leto (year) O 5,3 x10-6/mleto (myear) Sl. 4. Drevo napak - stalni izpust Fig. 4. Fault tree – continuous release V preglednici 3 je prikazano zaporedje dejavnosti pri pripravi, vklopu, obratovanju in izklopu rektifikacijskega sistema. Vidimo lahko, da so identificirane zlasti aktivnosti, katerih odsotnost bi povzročila napake v delovanju (primer: če so povezave med kolono in rezervoarji za destilat in destilacijski ostanek odprte, ima to negativne posledice za končni rezultat procesa). Iz navedenega je jasno razvidna potreba po obstoju tehnoloških postopkov, ki se jih operaterji zahtevnih procesnih sistemov držijo pri nadzoru delovanja teh sistemov. Splošni pogoji dela dajo obširno in dobro strukturirano bazo za karakterizacijo razmer, v katerih izvajamo določeno nalogo. Za vsako vrsto delovnih pogojev je treba določiti ustrezno stopnjo. Vsaki stopnji ustreza pričakovan vpliv na zanesljivost dela, kakor je določeno v preglednici 4, povzeti po [5]. Pri tem so s krepkim tiskom označene vrednosti, ki smo jih upoštevali za izračun obravnavane rektifikacijske kolone. Verjeten način nadzora določimo z oceno splošnih pogojev dela in določitvijo pričakovanega vpliva na zanesljivost izvedbe. Oceno splošnih pogojev dela prikažemo kot trojico [Zzmanjšan, Zbrez posebnosti, Zizboljšan]. Slika 5 prikazuje povezavo med splošnimi pogoji dela in načinom nadzora. Način nadzora določimo glede na polje, v katerem je presečišče vrednosti Zizboljšan in Zzmanjšan [5]. Table 3 shows activities during the preparation, operation, and turning off of the rectification system. We see that the activities, the lack of which could cause errors during the operation, are noted (i.e. if the connections between the column and reservoirs for distillate remain open this is detrimental to the final result of the process). Therefore, a need for clearly defined guidelines for system control is shown. Common performance conditions give a broad and well-structured basis for the characterization of conditions under which a particular task is performed. For each type of performance conditions one needs to define an appropriate level. Each level is associated with performance reliability, as defined in Table 4, according to Hollnagel [5], 1998. In Table 4 the conditions used for the actual calculations are written in bold. The probable control mode is defined using an assessment of common performance conditions and selecting the expected influence on the reliability of performance. Common performance conditions are shown as a triplet [Sreduced, Snot significant, Simproved]. Fig. 5 depicts the relationship between the common performance conditions and the control mode. The control mode is defined according to the intersection of Sreduced and Simproved [5]. | IgfirTHŽšIbJIlMIlgiCšD I stran 425 glTMDDC Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 3. Zaporedje dejavnosti pri pripravi, vklopu, obratovanju in izklopu rektif. sistema Table 3. Sequence of activities for preparing, start, operation and stopping of the rectification system OZNAKA MARK CILJ GOAL DEJAVNOST ACTIVITY 1.0 Priprava sistema Preparing of the system 1.1 Preverimo, ali so odprte povezave med kolono in rezervoarji za destilat in destilacijski ostanek. Check if connections between column and tanks of destillate and distillatory residue are open. 1.2 Zapremo ventile za odvzem destilata in destilacijskega ostanka. Close valves for destillate and distillatory residue taking away. 2.0 Vklop sistema Start of the system 2.1 Vključimo črpalko za kroženje glikola v kondenzatorjih. Start the pump for glycol circulation in condensers. 2.2 Vklopimo napajalno črpalko in napolnimo uparjalnik z mešanico topil. Start the feeder pump and fill up reboiler with components mixture. 2.3 Ko mešanica topil prekrije grelnik uparjalnika, odpremo ventil za gretje uparjalnika. When components mixture cover reboiler heater, open valve for reboiler heating. 3.0 Obratovanje sistema Operation of the system 3.1 Kolona mora vsaj 30 min delovati pri popolnem refluksu brez napajanja. The column has to operate at least 30 minutes by full reflux without feeding. 3.2 Odpremo ventil za odvzem destilata in destilacijskega ostanka. Open valves for destillate and distillatory residue. 3.3 Napajalno črpalko naravnamo na pretok 300 l/h. Feeder pump set for flow 300 l/h. 3.4 Temperaturo v refluksni glavi uravnavamo z ventilom za odvzem destilata na 56 °C. Control temperature in reflux head with valve for destillate taking away at 56°C. 3.5 Temperaturo na dnu kolone uravnavamo z ventilom za odvzem destilacijskega ostanka na 80 °C. Control temperature in column bottom with valve for distillatory residue taking away at 80 °C. 4.0 Izklop sistema Stopping of the system 4.1 Izklopimo napajalno črpalko. Stop feeder pump. 4.2 Zapremo ventil za gretje uparjalnika. Close valve for reboiler heating. 4.3 Zapremo ventil za odvzem destilacijskega ostanka. Close valve for distillatory residue taking away. 4.4 Odpremo ventil za odvzem destilata. Open valve for destillate taking away. 4.5 Izklopimo črpalko za kroženje glikola v kondenzatorjih. Stop pump for glycol circulation in condensers. Ob koncu osnovne metode je treba določiti The final result of the basic method is the območje zanesljivosti za vsakega od načinov nadzora, interval of reliability for each of the control modes ki so uporabni v primeru obravnavanega used in the case of the rectification system as analyzed rektifikacijskega sistema. in this contribution. Za obravnavani sistem smo ugotovili, da zanj For the system analyzed in this contribution velja trojka [Zzmanjšan, Zbrez posebnosti, we found the triplet [Sreduced, Snot significant, Zizboljšan] = [0,5,4]. Ugotovimo lahko, da je improved] = [0,5,4] to be valid. This gives a strategic presečišče vrednostiZzmanjšan inBzboljšan v polju, control mode area of intersection between Sreduced kjer je način nadzora strateški. Preglednica 5 kaže and Simproved. Table 5 presents the reliability interval zanesljivostno območje za strateški način nadzor: for the strategic control mode as: ^BsfTTWHIK | stran 426 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 4. Splošni pogoji dela in pričakovan vpliv na zanesljivost dela za obravnavani sistem Table 4. Common performance conditions and expected effect on performance reliability for relevant system VRSTA DELOVNIH RAZMER COMMON PERFORMANCE CONDITIONS OPIS EVALUATION STOPNJA LEVEL kakovost podpore in namenjena Primerna sredstva organizacije, za opravljanje organiziranost naloge; vključujoč komunikacijski ___________________sistem, sistem varstva pri delu Adequacy of organisation The quality of the support and resources provided by the organisation for the task being performed. This includes commu. system, Safety Management System. Delovne razmere osvetljenost prostora, bleščanje na zaslonih, hrup alarmov, motnje iz procesa, ... Working Ambient lighting, glare on conditions screens, noise from alarms, interruptions from the task, etc. Primerna zaščita kakovost zaščite človeka pred človeka pred strojem, informacije, dosegljive na strojem in ope- nadzornih ploščah, rativna podpora računalniško vodenje Adequacy of MMI and operational support The quality of of the MMI, control panels, workstations. Razpolaganje s razpolaganje s postopki in načrti, postopki ki vključujejo operativna in nepričakovana stanja Availability of procedures/planes The availability of prepared guideance for the work to be carried out, emergency proced.. Število hkratnih nalog Number of simultaneous goals število nalog, ki jih mora delavec opraviti ali biti pozoren v istem času__________________ The number of tasks or goals operators must attend to. Razpoložljiv čas čas, ki je na voljo za izvedbo naloge Available time The time available to complete the work. Čas dneva čas, v katerem je naloga ___________________opravljena_____________________ Time of day The time at which the task is ___________________carried out. raven in kakovost usposobljenosti Primerna operaterja, seznanitev z novo usposobljenost in tehnologijo, ponavljanje starih izkušnje spretnosti, stopnja operaterjeve ___________________izkušenosti_____________________ The level of readiness for the work. Adequacy of Includes familiarisation to training and new technology, refreshing old skills, the preparation level of operational experience. Kakovost kakovost sodelovanja članov sodelovanja skupine, stopnja zaupanja, v skupini splošno počutje članov v skupini ________________________________ Crew collaboration quality The quality of the collaboration. between crew members, the level of trust, the general social climate among crew members. zelo učinkovit PRIČAKOVAN VPLIV NA ZANESLJIVOST DELA EXPECTED EFFECT ON PERFORMANCE RELIABILITY izboljšan učinkovit brez posebnosti neučinkovit___________zmanjšan pomanjkljiv___________zmanjšan very efficient efficient improved inefficient not significant deficient improved ugoden improved izboljšan neznosen brez posebnosti advantageous zmanjšan compatible improved incompatible not significant v pomoč improved primeren izboljšan brez posebnosti neprimeren brez posebnosti supportive zmanjšan adequate improved tolerable not significant inappropriate not significant improved primeren___________izboljšan sprejemljiv brez posebnosti neprimeren appropriate zmanjšan acceptable improved inappropriate not significant pod zmožno improved primerno zmožnostim brez posebnosti brez posebnosti nad zmožnostmi fewer than capacity zmanjsan not significant matching curr. capacity not significant more than capacity improved primeren___________izboljšan začasno brez posebnosti neprimeren stalno neprimeren adequate zmanjšan temporarily inadequate improved not significant continuously inadequate improved dnevni čas brez posebnosti nočni c as day-time night-time not significant primeren, zelo izkušen improved izboljšan primeren, omejeno izk. brez posebnosti adequate, very experience improved adequate, lim. experience not significant inadequate zelo učinkovit improved učinkovit izboljšan neučinkovit brez posebnosti brez posebnosti pomanjkljiv very efficient zmanjsan efficient improved inefficient not significant deficient not significant improved Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis izboljšana V zanesljivost strateški improved strategic 1 tL taktični tactical oportunistični opportunistic nenačrtni scrambled zmanjšana zanesljivost >- - reduced reliability Sl. 5. Povezava med splošnimi pogoji dela in načinom nadzora [5] Fig. 5. Relations between common performance conditions and control modes by [5] Preglednica 5. Način nadzora in zanesljivostno območje [5] Table 5. Control modes and probability intervals [5] NAČIN NADZORA CONTROL MODE ZANESLJIVOSTNO OBMOČJE (VERJETNOST NAPAKE) RELIABILITY INTERVAL (PROBABILITY OF ACTION FAILURE) strateški strategic 0,5x10-5 < p < 1,0x10-2 taktični tactical 1,0x10-3 < p < 1,0x10-1 oportunistični opportunistic 1,0x10-2 < p < 0,5 nenačrtni scrambled 1,0x10-1 < p < 1,0 0,5x10 5 < p < 1,0x102 Ker je verjetnost človeške napake reda velikosti As the probability of human error exceeds that verjetnosti odpovedi rektifikacijskega sistema oz. je večja, of technical failure we continued the analysis with je bilo teba analizo nadaljevati z razširjeno metodo CREAM. the extended CREAM methodology. 4.2 Analiza z razširjeno metodo ASZN Namen razširjene metode ASZN [5] je, da natančneje ovrednotimo posamezne prispevke k skupni človeški napaki in jo uporabimo takrat, ko je človeška napaka enakovredna ali pomembnejša od tehnične napake, ovrednotene po osnovni metodi ASZN. V postopku izvedbe razširjene metode ASZN opravimo naslednje dejavnosti: - določimo poznavalne dejavnosti6, preglednica 6, - identificiramo najverjetnejše napake poznavalne funkcije7, preglednica 7, - določimo verjetnost napake za vsako verjetno napako poznavalne funkcije za rektifikacijski sistem, preglednica 8, 4.2 Extended CREAM methodology analysis The extended Cognitive Reliability and Error Analysis Method (Extended CREAM) was designed by Hollnagel [5] as a tool to improve quantification of particular contributions to common human error and is used when the human-error probability assessed with basic CREAM equals or is greater than the technical failure probability. In order to perform the extended CREAM the following activities should be undertaken: - define cognitive demands6 , Table 6, - identify cognitive function failures7 , Table 7, - define cognitive failure probability, Table 8, VBgfFMK stran 428 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis - določimo uravnane verjetnosti napak poznavalnih funkcij8 za rektifikacijski sistem, preglednica 10. Tako določeno vrednost napake lahko nato vključimo v drevo odpovedi in jo obravnavamo enako kakor smo obravnavali verjetnost okvare (napake iz tehničnih vzrokov). Najprej smo na podlagi generičnih poznavalnih dejavnosti definirali poznavalne dejavnosti z zahtevami poznavanja za rektifikacijski sistem. Ugotovimo lahko, da je za rektifikacijski sistem največja zahteva po izvajanju, temu pa sledita opazovanje in razlaga. Preglednica 6 prikazuje poznavalne dejavnosti z zahtevami poznavanja za rektifikacijski sistem. V nadaljevanju določimo najverjetnejše napake poznavalnih funkcij, uporabljenih za obravnavani rektifikacijski sistem, kar je prikazano v preglednici 7. V nadaljevanju določimo še nominalne verjetnosti napak poznavalnih funkcij. Te lahko določimo na temelju lastnih opazovanj ali na temelju dosegljivih podatkov iz literature. V konkretnem primeru smo verjetnosti povzeli po [5], ki podaja osnovne vrednosti ter skrajne meje območij. Iz vpliva splošnih delovnih pogojev na nominalno verjetnost napake poznavalne funkcije za rektifikacijski sistem določimo splošni uravnalni faktor (SUF) kot zmnožek posameznih uravnalnih faktorjev (UF9), kar storimo na podlagi utežnih količnikov uravnalnih faktorjev v skladu z razširjeno metodologijo ASZN. Izračun SUF je prikazan v preglednici 9. Končna vrednost uravnane verjetnosti napake poznavalnih funkcij (UVNPF) je zmnožek skupnega uravnalnega faktorja in nominalne verjetnosti napake poznavalnih funkcij (NVNPF). Uravnane verjetnosti napak poznavalnih funkcij za rektifikacijski sistem so prikazane v preglednici 10. V drevesi odpovedi za trenutni (sl. 3) in stalni izpust (sl. 4) so vključeni osnovni dogodki ki so posledica človeških napak. Drevo odpovedi s tehničnimi in človeškimi napakami za trenutni izpust je na sliki 6. V drevesi odpovedi so vključene samo človeške napake, ki imajo za posledico trenutni ali stalni izpust tekočinske mešanice iz rektifikacijskega sistema. 5 SINTEZA VERJETNOSTI NEZGODE (ČLOVEŠKE NAPAKE) IN OKVARE (TEHNIČNE NAPAKE) V DREVESU ODPOVEDI Na obravnavani način smo dobili vrednosti za verjetnosti človeških (nezgod) in mehanskih (okvar) napak, ki jih je moč uvrstiti v drevo odpovedi. Na sliki 6 je prikazano drevo odpovedi za trenutni izpust, na sliki 7 pa drevo odpovedi za stalni izpust. Prednost prikazanega je prav v uravnoteženju (deanimaciji1) objektivnih dogodkov (okvar) in subjektivnih dogodkov z objektivnimi posledicami (nezgod). Zdaj je mogoče z uporabo že prikazane Booleove algebre ponovno ovrednotiti vse rezultate z upoštevanjem in brez upoštevanja človeških napak, - define adjusted cognitive failure probability8 , Table 10. The final result is a quantified human-error probability, which can be included in a fault tree and treated as any other failure probability to arrive at a final combined value for failure probability. In order to arrive at the final result, we first define the cognitive demands based on generic cognitive demands. For our case, the execute cognitive demand was most frequently followed by observation and interpretation. The demands are summarized in Table 6. Then we defined the cognitive function failures most likely to occur in the system at hand.The results are summarized in Table 7. Further, we define the nominal cognitive failure probability. This can be defined based on our own observation or on published results. In our case we relied on the values of [5] who published basic values and upper and lower limits. Based on the effect of common performance conditions on cognitive function failures for the rectification system under observation we can define a common weighting factor as a product of weighting factors9 using the process shown in Table 9. The final value of the adjusted cognitive failure probability is the product of a common weighting factor and the nominal cognitive failure probability. These values are shown in Table 10. As a result, we have modified the fault trees for instantaneous (Fig.3) and continuous (Fig. 4) releases to include adjusted cognitive failure probabilities for both cases, shown in Fig. 6 for the instantaneous release case, and Fig. 7 for the continuous release case. 5 SYNTHESIS OF HUMAN-ERROR AND TECHNICAL FAILURE PROBABILITIES IN A FAULT TREE In the preceding sections we have shown the process of obtaining human-error and technical failure probabilities. The results can be inserted in a fault tree in order to compare the influence of either component. Fig. 6 shows a fault tree for instantaneous release, and Fig. 7 for continuous release. The advantage of the presented synthesis is in the deanimation10 of the objectively perceived events and the subjectively perceived human errors resulting in objectively perceived consequences of human errors (i.e. accidents) Now, we can re-evaluate the results already | lgfinHi(š)bJ][M]lfi[j;?n 02-8______ stran 429 I^BSSIfTMlGC Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis VBgfFMK Preglednica 6. Poznavalne dejavnosti z zahtevami poznavanja rektifikacijskega sistema Table 6. Cognitive activity with cognitive demand for rectification system # 1.1 1.2 2.1 2.2 2.3 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 4.4 4.5 DEJAVNOST ACTIVITY Preverimo, ali so odprte povezave med kolono in rezervoarji za destilat in destilacijski ostanek. Check if connections between column and tanks of destillate and distillatory residue are open. Zapremo ventile za odvzem destilata in destilacijskega ostanka. Close valves for destillate and distillatory residue taking away. Vključimo črpalko za kroženje glikola v kondenzatorjih. Start the pump for glycol circulation in condensers. Vklopimo napajalno črpalko in napolnimo uparjalnik z mešanico topil. Start the feeder pump and fill up reboiler with components mixture. Ko mešanica topil prekrije grelnik uparjalnika, odpremo ventil za gretje uparjalnika. When components mixture cover reboiler heater, open valve for reboiler heating. Kolona mora vsaj 30 min delovati pri popolnem refluksu brez napajanja. The column has to operate at least 30 minutes by full reflux without feeding. Odpremo ventil za odvzem destilata in destilacijskega ostanka. Open valves for destillate and distillatory residue. Napajalno črpalko naravnamo na pretok 300 l/h. Feeder pump regulate at flow 300 l/h. Temperaturo v refluksni glavi uravnavamo z ventilom za odvzem destilata na 56 °C. Control temperature in reflux head with valve for destillate taking away at 56°C. Temperaturo na dnu kolone uravnavamo z ventilom za odvzem destilacijskega ostanka na 80 °C. Control temperature in column bottom with valve for distillatory residue taking away at 80 °C._____________ Izklopimo napajalno črpalko. Stop feeder pump. Zapremo ventil za gretje uparjalnika. Close valve for reboiler heating. Zapremo ventil za odvzem destil. ostanka. Close valve for distillatory residue taking away. Odpremo ventil za odvzem destilata. Open valve for destillate taking away. Izklopimo črpalko za kroženje glikola v kond. Stop pump for glycol circulation in condensers. POZNAVALNA DEJAVNOST COGNITIVE ACTIVITY O IN N I Preveri Verify Izvedi Execute Izvedi Execute Izvedi Execute Krmili Control Nadzoruj Monitor Izvedi Execute Izvedi Execute Krmili Control Krmili Control Izvedi Execute Izvedi Execute Izvedi Execute Izvedi Execute Izvedi Execute Oznake: O - opazovanje, IN - interpretacija, N - načrtovanje, I - izvedba Mark: O - observation, IN - interpretation, N - planning, I - execution * * * * * * * * * * * * * * * * prikazanih v preglednici 2. Rezultati so prikazani v preglednici 11. Ugotovimo lahko, da človeške napake v mejah postavljenih predpostavk ne vplivajo na verjetnost trenutnega izpusta, skoraj za faktor 25 pa povečajo verjetnost stalnega izpusta. shown before with and without the human errors shown in Table 2. The results are shown in Table 11. We deduce that human errors do not influence (within the limits of the assumptions) instantaneous release while they increase the probability of continuous release almost 25 fold. stran 430 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 7. Verjeten način napak poznavalnih funkcij rektifikacijskega sistema Table 7. Potential cognitive function failures for rectification system # 1.1 Preveri Verify 1.2 Izvedi Execute 2.1 Izvedi Execute 2.2 Izvedi Execute 2.3 Krmili Control 3.1 Nadzoruj Monitor 3.2 Izvedi Execute POZNA-VALNA DEJAVNOST COGNITIVE ACTIVITY opazovanje observation O1 O2 O3 3.3 Izvedi Execute 3.4 Krmili Control 3.5 Krmili Control 4.1 Izvedi Execute 4.2 Izvedi Execute 4.3 Izvedi Execute 4.4 Izvedi Execute 4.5 Izvedi Execute * * * * * razlaga interpretation IN1 IN2 IN3 * * načrtovanje planning N1 N2 I1 I2 izvedba execution I3 I4 I5 * * * * * Ob analizi verjetnosti stalnega izpusta ugotovimo, da z vidika človeške napake nanjo vplivajo naslednje vrste napak poznavalne funkcije: - brez izpolnitve - napačna izpolnitev (2x). Bistveno vprašanje, ki se zastavi operaterju rektifikacijskega sistema, je tedaj, kako napake zmanjšati ali odpraviti. Kar se tiče okvar, so postopki znani in preskušeni ter zaobseženi v načelih obvladovanja kakovosti. Glede nezgod pa bi bilo najprej smiselno ugotoviti, ali bi bilo nezgode moč omejiti tako, da bi jih iz potencialnih nezgod prekvalificirali v potencialne okvare, da bi torej razosebili njihov vir. To bi bilo najpreprosteje moč storiti z avtomatizacijo posameznih elementov delovanja rektifikacijskega sistema - torej zamenjavo človeške podpore s strojno podporo. Ker pa namen tega prispevka ni predlagati dejanske izvedbene tehnike, temveč le prikazati orodje in metodologijo za objektivno analizo sicer subjektivnih vprašanj, se s tem nismo bolj poglobljeno ukvarjali. Glede same verjetnosti človeške napake pa menimo, da jo bo brez prekvalifikacije oz. zamenjave človeka z napravo moč najbolj zmanjšati v primeru Further analysis of the continuous release shows that the following cognitive function failures are the main contributors to the human error: - missed action - action of the wrong type (2x) The main question which the operator needs to answer is how to reduce or eliminate failures. As far as technical failures are concerned there are a number of procedures that are known under the umbrella of quality management. As far as human errors are concerned they should first be deanimated by switching them (conceptually and actually) from potential accidents into potential failures. This can be achieved by changing the human involvement with devices such as the automation of elements of the rectification system. As this is beyond the scope of this study we did not further explore the actual switch but it should, in our opinion, be performed at some point in the future. Regarding human error itself, and short of changing the human operator with a device, the following actions should be performed to reduce failure rates: - produce and use quality procedures and technical guidelines for operation, gfin^OtJJlMISCSD 02-8 stran 431 |^BSSITIMIGC Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 8. NVNPF osnovnih napak poznavalnih funkcij rektifikacijskega sistema Table 8. Nominal Cognitive Failur Probabilities (NCFP) of basic cognitive function failures for rectification system # DEJAVNOST VRSTA NAPAKE ACTIVITY ERROR MODE NVNPF NCFP 1.1 1.2 2.1 2.2 Preverimo, ali so odprte povezave med kolono in rezervoarji za destilat in destilacijski ostanek. Check if connections between column and tanks of destillate and distillatory residue are open. O3 brez opazovanja observation not made 7,0x10-2 Zapremo ventile za odvzem destilata in destilacijskega ostanka. Close valves for destillate and distillatory residue taking away. I1 napačna izpolnitev action of wrong type 3,0x10-3 Vključimo črpalko za kroženje glikola v kondenzatorjih. Start the pump for glycol circulation in condensers. I5, brez izpolnitve missed action 3,0x10-2 Vklopimo napajalno črpalko in napolnimo uparjalnik z mešanico topil. Start the feeder pump and fill up reboiler with components mixture. I2 nepravočasna izpolnitev action at wrong time 3,0x10-3 2.3 3.1 3.2 3.3 3.4 Ko mešanica topil prekrije grelnik uparjalnika, odpremo ventil za gretje uparjalnika. When components mixture cover reboiler heater, open valve for reboiler heating. O3 brez opazovanja observation not made 7,0x10-2 Kolona mora vsaj 30 min delovati pri popolnem refluksu brez napajanja. The column have to operate at least 30 minutes by full reflux without feeding. O3 brez opazovanja observation not made 7,0x10-2 Odpremo ventil za odvzem destilata in destilacijskega ostanka. Open valves for destillate and distillatory residue. I2 nepravočasna izpolnitev action at wrong time 3,0x10-3 Napajalno črpalko naravnamo na pretok 300 l/h. Feeder pump set for flow 300 l/h. O3, brez opazovanja observation not made 7,0x10-2 Temperaturo v refluksni glavi uravnavamo z ventilom za odvzem destilata na 56 °C. Control temperature in reflux head with valve for destillate taking away at 56°C. I1 napačna izpolnitev action of wrong type 3,0x10-3 3.5 4.1 4.2 4.3 Temperaturo na dnu kolone uravnavamo z ventilom za odvzem destilacijskega ostanka na 80 °C. Control temperature in column bottom with valve for distillatory residue taking away at 80 °C. I1 napačna izpolnitev action of wrong type 3,0x10-3 Izklopimo napajalno črpalko. Stop feeder pump. I5, brez izpolnitve missed action 3,0x10-2 Zapremo ventil za gretje uparjalnika. Close valve for reboiler heating. I5, brez izpolnitve missed action 3,0x10-2 Zapremo ventil za odvzem destilacijskega ostanka. Close valve for distillatory residue taking away. I4, napačno zaporedje izpolnitev action out of sequence 3,0x10-3 4.4 4.5 Odpremo ventil za odvzem destilata. Open valve for destillate taking away. I4, napačno zaporedje izpolnitev action out of sequence 3,0x10-3 Izklopimo črpalko za kroženje glikola v kondenzatorjih. Stop pump for glycol circulation in condensers. I2, nepravočasna izpolnitev action at wrong time 3,0x10-3 upravljanja rektifikacijske kolone: - education and training of the operator. - z izdelavo kakovostnih tehničnih navodil za delo in Procedures and guidelines should include - občasnim usposabljanjem upravljalca. unusual events, the consequences of which are V navodila in usposabljanje je treba vključiti primarily dependent on the rapid reaction of the tudi neobičajne dogodke, katerih posledice so odvisne operator. The scenarios, however, which could be predvsem od hitre in prisebne reakcije upravljalca. included in this venue is outside of the scope of this Tudi sestava takih scenarijev je zunaj želenega dometa study and should be performed by people involved tega prispevka in pravzaprav spada v študij dela. in human-resources management. ^BSfirTMlllC | stran 432 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 9. Vpliv splošnih delovnih razmer na nominalno verjetnost napake poznavalnih funkcij rektifikacijskega sistema Table 9. Effects of common performance conditions on cognitive function failures for rectification system VRSTA DELOVNIH RAZMER COMMON PERFORMANCE CONDITION Primerna organiziranost Adequacy of organisation Delovne razmere Working conditions STOPNJA LEVEL 1.1 1.2 2.1 2.2 2.3 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 4.4 4.5 učinkovit efficient Primerna zaščita človeka pred strojem in operativna podpora Adequacy of MMI and operational support znosen compatible 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 znosen tolerable 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Razpolaganje s postopki Availability of procedures/planes Število istočasnih nalog Number of simultaneous goals Razpoložljiv čas Available time________________ Čas dneva Time of day primeren appropriate primerno zmožnostim matching curr. capacity primeren adequate Primerna usposobljenost in izkušnje Adequacy of training and preparation dnevni čas day-time 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Kakovost sodelovanja v skupini Crew collaboration quality primeren, zelo izkušen adequate, very experience 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 0,8 SKUPNI URAVNALNI FAKTOR TOTAL INFLUENCE OF CPC zelo učinkovit very efficient 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 0,16 Preglednica 11. Primerjava rezultatov analiz drevesa odpovedi z upoštevanjem in brez upoštevanja človeških napak Table 11. Comparision of Fault-Tree Analyse results with and without including human errors KRITERIJ CRITERION TEHNIČNE NAPAKE TECHNICAL FAILURES TEH. IN ČLOVEŠKE NAPAKE TECHNICAL AND HUMANS FAILURES___________________ TRENUTNI IZPUST INSTANTANEOUS RELEASE VERJETNOST DOGODKA PROBABILITY OF FAILURE 4,6x10-5 STALNI IZPUST CONTINUOUS RELEASE 2,0x10-4 4,6x10-5 4,9x10-3 6 SKLEP V pričujočem delu smo na kratko predstavili metodologijo, ki jo je po našem mnenju primerno upoštevati pri analizi delovanja zahtevnih sistemov. Najprej smo analizirali verjetnost napake trenutnega in stalnega izpusta iz rektifikacijskega sistema zaradi tehnične (mehanske) napake, kar smo storili z uporabo metode drevesa odpovedi in Booleove algebre. Nato smo obravnavali sistem z vidika človeških napak ter ga analizirali z metodologijo ASZN. Bistveni prispevek tega dela je v sintezi obeh vplivov, to je vpliv nezgod (človeške napake) in odpovedi (tehnične napake) v drevesu odpovedi. Po sintezi smo ugotovili, dačloveška napaka na trenutni izpust bistveno ne vpliva (da je torej dominantna tehnična napaka), pač pa lahko bistveno vpliva na stalni izpust. Analiza je pokazala še na glavne vire človeške napake, in sicer na napako, ki se pokaže kot neizpolnitev naloge in napačno izpolnitev naloge. Te napake je moč odpraviti z izdelavo dobrih tehničnih navodil za delo in občasnim usposabljanjem operaterja. Druga možnost je avtomatizacija tistih ponavljajočih se dejavnosti, ki bistveno prispevajo k verjetnosti nezgode. 6 CONCLUSION This study deals mainly with methodology, which should, in our opinion, be used for an analysis of complex-system operation. First, the probability of technical failure for instantaneous and continuous releases was analyzed using fault-tree analysis and Boolean algebra. Then, the same system was presented from the human-error perspective and analyzed using CREAM methodology. The main thrust of this work was in the synthesis of both methodologies, i.e. the influence of human errors and technical failures within the framework of the fault-tree analysis. The results have shown that human failure is almost negligible for instantaneous release, and of significance for continuous release. The analysis further identifies the main sources of human error as missed action and action of the wrong type. These errors could be mitigated using technical guidelines of sufficient quality and the periodic training of operators. The second possibility is switching the operations from human operator to activities operated using devices for those repetitive activities which could be the main contributors to the accidents as analyzed. Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis Preglednica 10. Uravnane verjetnosti napak poznavalnih funkcij za rektifikacijski sistem Table 10. Adjusted CFPs (ACFP) for rectification system 1.1 1.2 2.1 2.2 2.3 3.1 3.2 3.3 3.4 3.5 4.1 4.2 4.3 4.4 4.5 DEJAVNOST ACTIVITY ERROR MODE Preverimo, ali so odprte povezave med kolono in rezervoarji za destilat in destilacijski ostanek. Check if connections between column and tanks of destillate and distillatory residue are open. Zapremo ventile za odvzem destilata in destilacijskega ostanka. Close valves for destillate and distillatory residue taking away. Vključimo črpalko za kroženje glikola v kondenzatorjih. Start the pump for glycol circulation in condensers. Vklopimo napajalno črpalko in napolnimo uparjalnik z mešanico topil Start the feeder pump and fill up reboiler with components mixture. Ko mešanica topil prekrije grelnik uparjalnika, odpremo ventil za gretje uparjalnika. When components mixture cover reboiler heater, open valve for reboiler heating. Kolona mora vsaj 30 min delovati pri popolnem refluksu brez napajanja. The column have to operate at least 30 minutes by full reflux without feeding. Odpremo ventil za odvzem destilata in destilacijskega ostanka. Open valves for destillate and distillatory residue. Napajalno črpalko naravnamo na pretok 300 l/h. Feeder pump set for flow 300 l/h. Temperaturo v refluksni glavi uravnavamo z ventilom za odvzem destilata na 56 °C. Control temperature in reflux head with valve for destillate taking away at 56°C. Temperaturo na dnu kolone uravnavamo z ventilom za odvzem destilacijskega ostanka na 80 °C. Control temperature in column bottom with valve for distillatory residue taking away at 80 °C. Izklopimo napajalno črpalko. Stop feeder pump. Zapremo ventil za gretje uparjalnika. Close valve for reboiler heating. Zapremo ventil za odvzem destilacijskega ostanka. Close valve for distillatory residue taking away. Odpremo ventil za odvzem destilata. Open valve for destillate taking away. Izklopimo črpalko za kroženje glikola v kondenzatorjih. Stop pump for glycol circulation in condensers. VRSTA NAPAKE O3 brez opazovanja observation not made I1 napačna izpolnitev action of wrong type I5 brez izpolnitve missed action I2, nepravočasna izpolnitev action at wrong time O3 brez opazovanja observation not made O3 brez opazovanja observation not made I2 nepravočasna izpolnitev action at wrong time O3 brez opazovanja observation not made I1 napačna izpolnitev action of wrong type I1 napačna izpolnitev action of wrong type I5, brez izpolnitve missed action I5, brez izpolnitve missed action I4, napačno zaporedje izpol. action out of sequence I4, napačno zaporedje izpol. action out of sequence I2, nepravočasna izpolnitev action at wrong time NVNPF NCFP 7,0x10-2 0,16 1,1x10-2 3,0x10-3 0,16 4,8x10-4 3,0x10-2 0,16 4,8x10-3 3,0x10-3 0,16 4,8x10-4 7,0x10-2 7,0x10-2 0,16 1,1x10-2 SUF WF UVNPF ACFP 0,16 1,1x10-2 3,0x10-3 0,16 4,8x10-3 7,0x10-2 0,16 1,1x10-2 3,0x10-3 0,16 4,8x10-4 3,0x10-3 0,16 4,8x10-4 3,0x10-2 0,16 4,8x10-3 3,0x10-2 0,16 4,8x10-3 3,0x10-3 0,16 4,8x10-4 3,0x10-3 0,16 4,8x10-4 3,0x10-3 0,16 4,8x10-4 VBgfFMK stran 434 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis TRENUTNI IZPUST INSTANTANEOUS RELEASE izpust release 9 napaka pri napajanju charging failure napaka pri ločev anju separation failure I ločevanje separation napaka pri uparjanju evaporation f ailure napaka pri kondenzaciji condensation failure je sesutje kolone column rupture prelom ce vi line rupture K TI L-L O 2,6 x 10-7mleto (myear) tehnična napaka technical fa ilure človeška napaka human err or T O 6,5 x 10-6/leto (year) č Q 3.4 I1 3.5 I1 č-1 Č-2 TT O 4,8 x 10-4 4,8 x 10-4 Sl. 6. Drevo napake s tehničnimi in človeškimi napakami - trenutni izpust Fig. 6. Synthesis of human error and fault-tree analysis - instantaneous release STALNI IZPUST CONTINUOUS RELEASE izpust release Q napaka pri ločevanju separation failure napaka pri napajanju charging failure ločevanje separation E poškodba ce vi line leak pošk. plašča kolone column shall leak I L-L* I O 5,3 x 10-6/mleto (myear) K* Q tehnična napaka technical failure človeška napaka human er ror T XT 1,0 x 10-5/leto (year) Č Q 3.4. I1 3.5. I1 Č-1 O 4,8 x 10-4 Č-2 napaka pri uparjanju evaporation failure napaka pri kondenzaciji condensation failure pošk. plašča kond. 1 cond. 1 shall leak C-1* o 1,0 x 10-5/leto (year) _______I pošk. plašča kond. 3 cond. 3 shall leak C-3* O 1,0 x 10-5/leto (year) kondenzacija condensation 5 pošk. plašča kond. 2 cond. 2 shall leak I C-2* I O 1,0 x 10-5/leto (year) poškodba ce vi line leak | L-C* | O 8,8 x10-6/mleto (myear) 2.1. I5 O Č-3 O Sl. 7. Drevo napake s tehničnimi in človeškimi napakam i - stalni izpust Fig. 7. Synthesis of human error and fault-tree analysis - continuous release 4,8 x 10 Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis 1 Z mehanskimi sistemi imamo v mislih vse sisteme, ki niso odvisni od človeškega odziva, ne glede na to, za kakšne sisteme gre - sem spadajo npr. cevi, ventili, tlačne posode, zvari ipd. 2 Med uporabnike štejemo menedžerje, zavarovalnice, sodne izvedence, tehnologe in druge, ki za svoje odločitve uporabljajo podatke o verjetnosti ali možnosti okvare ali porušitve posamezne naprave. 3 Glede na krajšanje dobe, ki je potrebna za doseganje družbeno sprejemljive spretnosti pri ravnanju s stroji in višanje števila nosilcev tako pridobljene izobrazbe je ta predpostavka konzervativna. 4 Z izrazom splošni pogoji dela po [5] označujemo obširen in dobro strukturiran temelj za označevanje pogojev, pri katerih naj bi se delo izvajalo. Osnovna predpostavka njihove uporabe je, da so medsebojno odvisni in da zato preprost seštevek ne pomeni še skupne ocene splošnih pogojev dela. V posledici medsebojne odvisnosti mora biti skupna ocena izračunana tako, da upošteva način medsebojne odvisnosti. 5 Sklepni korak osnovne metode je določitev verjetnega načina nadzora na podlagi kombinacije števila posameznih vplivnih parametrov (od 9 skupnih), ki so bodisi zmanjšani, niso spremenjeni, ali izboljšani ([S zmanjšan, S brez posebnosti, S izboljšan]), pri čemer trojka [9,0,0] opiše najmanj zaželeno stanje, trojka [0,2,7] pa najbolj želeno stanje. 6 Z izrazom poznavalne dejavnosti [5] označujemo posamezne poznavalne (prepoznavalne, kognitivne) dejavnosti, ki so značilne za vsakega od korakov iz osnovne metode. Te posamezne dejavnosti so uporabljene za gradnjo poznavalnega profila (Cognitive Profile) za bistvene segmente opravila, osnovane na funkcijah (t.i poznavalnih funkcijah), ki so opisane s poznavalnim (kognitivnim) modelom. Poznavalne funkcije so uporabljene za prepoznavanje posameznih poznavalnih dejavnosti (npr. z opazovanjem kot funkcijo opravimo dejavnost verifikacije ali dejavnost spremljanja). 7 Z izrazom napake poznavalne funkcije so [5] označene napovedane napake, do katerih lahko pride pri izvedbi poznavalnih funkcij (npr. pri opazovanju kot funkciji lahko pride do napak opazovanja, ki imajo lahko neposredni vpliv na poznavalne dejavnosti, npr. na spremljanje). 8 Različne napake poznavalnih funkcij imajo različen učinek na končni rezultat, zato je posamezne napake poznavalne funkcije treba primerno utežiti. 9 Uravnalni faktor po [5] iz [9], ki za učinek posamezne poznavalne funkcije na posamezno poznavalno aktivnost določa utež. Ta izvira iz izkušenj in znaša za nevtralni položaj 1.0, za položaj, ki izboljšuje stanje manj ko 1 in za položaj, ki stanje slabša, več ko 1. Tako npr. primerna dostopnost načrtov in postopkov pomeni 20% zmanjšanje verjetnosti napake (uravnalni faktor 0,8), sprejemljiva dostopnost pomeni nevtralno stanje (UF=1,0), neprimerna dostopnost pa 100% povečanje verjetnosti napake (UF=2). Značilna za tako porazdelitev je penalizacija, ki kaznuje slabšanje položaja in posledično vnaša konzervativnost v določanje UF. 10 Deanimation, po Raven, J., osebna komunikacija. ^BSfirTMlliC | stran 436 1 With mechanical or technological systems one describes all systems that are not directly dependent on human response without regard to actual systems - such as piping, valves, pressure vessels, welds etc. 2 Such as insurance companies, managers, court experts, system engineers and others on a need-to-know basis regarding the probability of failure. 3 This is a conservative assumption given the reduction in time needed for qualification as a machinist and inflation in the number of graduates of technical schools. 4 Common performance conditions were suggested by Hollnagel [5] to describe well-structured foundation for description of conditions for work performance. The basic assumption of their use is common interdependence and the fact that a simple sum does not equal common performance conditions. Interdependence also requires taking into account its mode. 5 The final step of the basic method is the evaluation of a probable control mode based on the combination of a number of important parameters (numbering 9) which can either be reduced, are not significant, or are improved [S reduced, S not significant, S improved] where the triplet [9,0,0] stands for least-desirable situation, and the triplet [0,2,7] for most-desirable situation. 6 Hollnagel [5] defines the cognitive demands that are characteristic for each of the basic method steps. These demands are used to build a cognitive profile for important segments of a particular action and are based on a cognitive function. These functions are used for either recognizing a particular cognitive demand (e.g. with observation as a function the activity of monitoring is made). 7 Cognitive function failures Hollnagel [5] describes potential failures that can occur during the execution of cognitive functions (i.e. observation as a function can result in observation failures, and these failures may directly influence execution). 8 Different cognitive failures may have a different influence on the final result, which requires different weights to be applied to cognitive functions. 9 Hollnagel [5] has adopted weighting factors from Williams [9] who defines the weight for the effect of each particular cognitive function on cognitive demand. The weight (weighting factor) is based on experience and equals 1.0 for neutral (not significant) position, less than 1 for improvements, and more than 1 for reduction. For example, good access to plans and procedures means a 20% reduction in probability of error (i.e. weight of 0.8), while adequate access means not significant position with a weight of 1.0, and inadequate access increase for 100%, i.e. a weight of 2.0. This method means penalization of worsening of position and results in a conservative weight definition. 10 From Raven, J., personal communication. Zupan~i~ J. - Marn J.: Sinteza analize ~love{ke napake - The Synthesis of Human-Error Analysis 7 LITERATURA 7 REFERENCES [I] Kožuh, M. (1999) Odkrivanje in vrednotenje latentnih pomanjkljivosti v kompleksnih tehnoloških sistemih, Fakulteta za strojništvo, Ljubljana, Doktorska disertacija, 207. [2] Jordan Cizelj, R. (2001) Ocena stanja komponent jedrskih sistemov z uporabo teorije verjetnosti in teorije mehkih množic, Fakulteta za matematiko in fiziko, Ljubljana, Doktorska disertacija. [3] Kožuh, M., B. Mavko (1994) Comparing different system configurations and success criteria by the use of Fault tree technique for Instrument Air System. V: STRITAR, Andrej (ur.). International Meeting PSA/ PRA and Severe Accidents ‘94, Ljubljana, Slovenia, 17.-20. April. [4] Cepin, M., R. Jordan-Cizelj, M. Kožuh (1994) AC/DC power supply system fault tree analysis”. V: Thermal Reactor Safety Assessment: Proceedings of the conference organized by the British Nuclear Energy Society, Manchester, 23-26 May. [5] Hollnagel, E. (1998) Cognitive reliability and error analysis method, Institutt for Energiteknikk Halden, Norway, ISBN 0-08-0428487. [6] Kožuh, M., J. Peklenik (1999) A method for identification and quantification of latent weaknesses in complex systems, Cognition, Technology & Work, vol. 1, no. 4, 211-221. [7] Center for chemical process safety: Guidelines for chemical process quantitative risk analysis, American Institute of Chemical Engineers, 1989. [8] Sutton, I.S. (1992) Process reliability and risk management, Van Nostrand Reinhold New York [9] Williams, J.C. (1988) A data-based method for assessing and reducing human error to improve operational performance, Proceedings of IEEE 4th Conference on Human factors in Power Plants, Monterey, CA 6-9 June. [10] Zupančič, J. (2001) Analiza tehničnih in človeških napak rektifikacijskega sistema, poročilo o individualnem raziskovalnem delu (IRD), Fakulteta za strojništvo Univerze v Mariboru. [II] Bainbridge, L., Ironies of automation, http://www.bainbrdg.demon.co.uk/index.htm [12] Zupančič, J. (2002) Varnost in zanesljivost rektifikacijske kolone, magistrska naloga, Fakulteta za strojnitvo, Maribor. Naslova avtorjev:mag. Janja Zupančič Krka, d.d., Novo mesto Šmarješka c. 6 8000 Novo mesto prof.dr. Jure Marn Fakulteta za strojništvo Univerza v Mariboru Smetanova 17 2000 Maribor jure.marn@uni-mb.si Authors’ Addresses:Mag. Janja Zupančič Krka, d.d., Novo mesto Šmarješka c. 6 8000 Novo mesto, Slovenia Prof.Dr. Jure Marn Faculty of Mechanical Eng. University of Maribor Smetanova 17 2000 Maribor, Slovenia jure.marn@uni-mb.si Prejeto: Received: 18.1.2002 Sprejeto: Accepted: 20.9.2002 © Strojni{ki vestnik 48(2002)8,438-448 © Journal of Mechanical Engineering 48(2002)8,438-448 ISSN 0039-2480 ISSN 0039-2480 UDK 536.7:532.5:004.94 UDC 536.7:532.5:004.94 Izvirni znanstveni ~lanek (1.01) Original scientific paper (1.01) Izviren kombiniran ve~fazni model me{alne faze eksplozije pare An Original Combined Multiphase Model of the Steam-Explosion Premixing Phase Matja` Leskovar - Borut Mavko V večfaznem toku so lahko faze razporejene tako, da večfaznega toka ni mogoče obravnavati niti samo z modeli proste površine niti samo z modeli večfaznega toka. Taksno porazdelitev faz srečujemo na primer pri izotermnih preskusih mešalne faze eksplozije pare, kjer razpršene kroglice prodirajo v vodo, medfazna ploskev voda - zrak pa se ne razprši in ostane ostra. Pri modeliranju izotermnih mešalnih preskusov so običajno obravnavane vse tri faze, to so voda, zrak in kroglice, enakovredno z modeli večfaznega toka. Tako je obravnavana medfazna ploskev voda - zrak kot razpršen tok mehurčkov zraka v vodi oziroma kapljic vode v zraku, kar je fizikalno neustrezna slika in zaradi togih medfaznih sklopitvenih členov tudi numerično težko rešljiva naloga. Zato smo si zamislili, da bi izotermni mešalni proces obravnavali z izvirnim kombiniranim večfaznim modelom, pri katerem bi kroglice obravnavali kot običajno z modelom večfaznega toka, medtem ko bi medfazno ploskev voda - zrak obravnavali z modelom proste površine. Z razvitim kombiniranim večfaznim modelom smo simulirali izotermni preskus Q08, ki so ga izvedli na napravi QUEOS. Najbolj problematičen del simuliranja izotermnega mešalnega preskusa je pravilna napoved plinskega stebra, ki se oblikuje med prodiranjem kroglic v vodo. Da bi bolje spoznali, kako se plinski steber oblikuje, smo opravili obsežno parametrično analizo (velikost mreže, začetno debelino medfazne ploskve voda - zrak, gostoto vode, položaj vključitve medfazne sklopitve gibalne količine). Ugotovili smo, da se plinski steber oblikuje tako kakor pri preskusu le, če v modelu medfazno trenje kroglic na vodni gladini obravnavamo na poseben način, ki upošteva nezveznost prehoda zrak - voda. © 2002 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: tok večfazni, modeli večfazni, eksplozija parne, metode z nivojsko funkcijo, simuliranje) In multiphase flow, different phase distributions can occur that cannot be adequately modeled with just free-surface models or with just multiphase models. Such a distribution of phases occurs, for example, in isothermal steam-explosion premixing experiments, where dispersed spheres penetrate the water and the water-air surface remains sharp. A common practice when modeling isothermal premixing experiments is to treat all three phases involved - the water, the air and the spheres’ phase - equally, with multiphase flow models. In this way the water-air surface is treated as a dispersed flow of bubbles in water or droplets in air, which is a physically incorrect picture and because of very strong momentum-coupling terms also numerically not an easily solvable problem. Therefore, we decided to develop an original, combined multiphase model, where the spheres are treated, as is usual, with a multiphase flow model, whereas the water-air surface is treated with a free-surface model. The QUEOS isothermal premixing experiment Q08 was simulated with the developed combined multiphase model. A crucial part in isothermal premixing experiment simulations is the correct prediction of the gas chimney, which forms during the spheres’ penetration into the water. To get a better understanding of the gas-chimney formation an extensive parametric analysis (mesh size, initial water-air surface thickness, water density, interfacial momentum-coupling starting position) was performed. We established that the right gas-chimney formation can be obtained if a special spheres’ drag treatment at the water-air surface, which considers the discontinuous air-water transition, is incorporated into the model. © 2002 Journal of Mechanical Engineering. All rights reserved. (Keywords: multiphase flow, multiphase models, steam explosion, level set methods, simulations) 0 UVOD Porazdelitev faz v večfaznem toku je lahko različna. Tako so lahko faze na primer razporejene v večja območja, ki so med seboj ločena z gladko medfazno 0 INTRODUCTION In multiphase flow different phase distributions can occur, these range from unmixed-phase distributions, where the phases are arranged VBgfFMK stran 438 Leskovar M. - Mavko B.: Izvirni kombinirani ve~fazni - An Original Combined Multiphase ploskvijo (npr. stratificiran tok). Takšne večfazne tokove opisujemo z modeli proste površine, ki temeljijo na reševanju Navier-Stokesovih enačb ob upoštevanju medfaznih robnih pogojev. Drugo skrajnost pomenijo večfazni tokovi z razpršenimi fazami (npr. mehurčkast tok), pri katerih je medfazno ploskev praktično nemogoče spremljati in jih zato opisujemo z modeli večfaznega toka ki temeljijo na manj natančnih povprečenih Navier-Stokosovih enačbah. Med tema obema skrajnostma (ločene faze - razpršene faze) obstajajo še številne porazdelitve faz, ki jih ni mogoče obravnavati niti samo z modeli proste površine niti samo z modeli večfaznega toka. Te porazdelitve faz lahko razdelimo v dve skupini. Prvo skupino predstavljajo tiste porazdelitve faz, pri katerih so faze razpršene le na določenih območjih, medtem ko so drugje ločene z gladko medfazno ploskvijo [1]. Takšna porazdelitev faz se pojavi na primer v kasnejši fazi razvoja Kelvin-Helmholtzove nestabilnosti. Drugo skupino pa predstavljajo tiste porazdelitve faz, pri katerih so nekatere faze ločene z gladko medfazno ploskvijo, medtem ko so druge faze razpršene. Takšno porazdelitev faz srečamo na primer pri izotermnih preskusih mešalne faze eksplozije pare, pri katerih spuščajo različne curke hladnih kroglic v posodo, napolnjeno z vodo [2]. V tem prispevku bomo predstavili izvirni kombinirani večfazni model, ki smo ga razvili za modeliranje izotermnih preskusov mešalne faze parne eksplozije [3]. Nova zasnova obravnave večfaznih tokov je dovolj splošna, da jo je mogoče preprosto prilagoditi tudi za obravnavo vseh drugih porazdelitev faz druge obsežne skupine faznih porazdelitev. 1 MODELIRANJE VEČFAZNEGA TOKA Pri modeliranju izotermnih mešalnih preskusov so običajno obravnavane vse faze, to so voda, zrak in kroglice, enakovredno z modeli večfaznega toka [4]. Ti modeli večfaznega toka temeljijo na predpostavki, da vsaka faza z določeno fazno verjetnostjo kot oblak zaseda celotno simulirno območje in da so faze med seboj povezane z medfaznimi sklopitvenimi členi. Značilnost izotermnih mešalnih preskusov je, da ostaneta voda in zrak med celotnim preskusom ločena z gladko medfazno ploskvijo, kakor je shematično prikazano na sliki 1, kjer so predstavljene tri mrežne celice. Indeksa a in w označujeta fazi zraka in vode, Dv pa je razlika vektorjev hitrosti zraka in vode. Pri modelu večfaznega toka opisujemo medfazno ploskev voda - zrak kot razpršen tok mehurčkov zraka v vodi oz. kapljic vode v zraku (sl. 1), kar je fizikalno neustrezna slika. Ker so medfazni sklopitveni členi gibalne količine v razpršenih tokovih, pri katerih je razmerje gostot faz veliko, togi, so pri izrecnih numeričnih metodah potrebni zelo majhni časovni koraki, pojavijo pa se tudi težave s konvergenco [5]. Poleg tega se medfazna ploskev voda - zrak numerično razprši zaradi numerične difuzije in larger regions separated by a smooth interface (for example, stratified flow), to mixed distributions, where the phases are dispersed and it is practically impossible to track the phase interfaces (for example, bubbly flow). In between there is a variety of phases’ distributions, which cannot be adequately modeled with just free-surface models, which are based on Navier-Stokes equations that consider the interface boundary conditions, or just with multiphase flow models, which are based on less accurate, averaged Navier-Stokes equations. In general, these phase distributions can be classified in two groups. The first group comprises cases where the phases are only dispersed in some domains, whereas elsewhere the phase interfaces are smooth [1]. Such a phase distribution occurs, for example, at a late stage of the Kelvin-Helmholtz instability. The second group comprises cases where some phases are separated with a smooth interface, whereas the other phases are dispersed. Such a phase distribution occurs, for example, in isothermal steam-explosion premixing experiments, where different jets of cold spheres are injected into a water pool [2]. In this paper an original combined multiphase model developed for isothermal steam-explosion premixing experiments modeling will be presented [3]. This new concept of multiphase-flow treatment is general enough for it to be easily adapted to all other cases of phase distribution of the comprehensive second-phase distributions group. 1 MULTIPHASE FLOW MODELING A common practice in isothermal premixing experiments modeling is to treat all three phases involved – the water, the air and the spheres’ phase – equally with multiphase flow models [4]. These multiphase flow models are based on the assumption that each of the phases occupies, with a given phase-presence probability, the whole simulated region as a cloud, and that the phases interact through interfacial coupling terms. The special feature of isothermal premixing experiments is that the water and air phases remain separated by a free surface during the whole experiment, as shown schematically in Figure 1, where three mesh cells are presented. The indices a and w correspond to the air and water phases and D vr aw is the difference between the air- and water-velocity vectors. In the multiphase flow model the water-air surface is treated as a dispersed flow of air bubbles in water or water droplets in air (Fig. 1), which is a physically uncorrect picture. Since the interfacial momentum coupling terms in dispersed flows of fluids with high density ratios are very stiff, convergence problems occur and in explicit numerical methods extremely small time steps have to be used [5]. In addition, since in multiphase flow models | lgfinHi(š)bJ][M]lfi[j;?n 02-8______ stran 439 I^BSSIfTMlGC Leskovar M. - Mavko B.: Izvirni kombinirani ve~fazni - An Original Combined Multiphase [6], ker pri modelih večfaznega toka medfazni ploskvi ne posvečamo posebne pozornosti. Zato smo se odločili, da bomo medfazno ploskev voda - zrak obravnavali z modelom proste površine in tako odpravili vse omenjene pomanjkljivosti obravnave medfazne ploskve z modelom večfaznega toka, ki ni primeren za takšne probleme. Pri modelih proste površine uporabljamo za zasledovanje stične površine posebne algoritme, na stični površini pa vzamemo povprečne lastnosti faz (sl. 1). Ker se faze ne mešajo, zadošča za opis večfaznega toka eno hitrostno polje. Formalno lahko zato vodo in zrak obravnavamo kot eno, združeno fazo z nezveznimi faznimi lastnostmi na medfazni ploskvi voda - zrak in tako lahko izotermni mešalni potek obravnavamo kot navidez dvofazen tok razpršenih kroglic v kontinuumu združene faze voda - zrak. To je bistvo izvirnega kombiniranega večfaznega modela, pri katerem kroglice obravnavamo z modelom večfaznega toka, združeno fazo voda - zrak pa z modelom proste površine. no special attention is given to the phases’ interface, the water-air surface numerically spreads due to numerical diffusion [6]. Therefore, we decided to treat the water-air surface with a free-surface model and suppress, in this way, all the mentioned drawbacks of treating the phases’ interface with multiphase flow models, which are not suited for such problems. In free-surface models special interface-tracking algorithms are used, and since the phases do not mix the phases’ flow is described with only one velocity field. At the phase interfaces the average phase properties are taken (Fig. 1). In this way the water and air phases can be regarded as a single, joint phase with discontinuous phase properties at the water-air interface, and consequently the isothermal premixing process can be treated as a quasi two-phase flow of dispersed spheres in the continuous joint water-air phase. This is the essence of the original combined multiphase model, where the spheres are treated with a multiphase flow model and the joint water-air phase with a free-surface model. preskus experiment model proste površine model večfaznega toka free-surface model multiphase flow model ra ra ,rw D vr aw = 0 r ra aw r D vr aw = 0 r ra Pa ,Pw 0 aw rw Sl. 1. Obravnava medfazne ploskve voda - zrak pri modelu proste površine in modelu večfaznega toka Fig. 1. Water-air surface treatment in the free-surface model and the multiphase flow model 2 METODA Z NIVOJSKO FUNKCIJO Vsako fazo v tako definiranem navidez dvofaznem toku, razpršeno fazo kroglic in kontinuum združene faze voda - zrak, smo opisali s kontinuitetno in gibalno enačbo, kar je opisano v [7] in [8]. Medfazno ploskev voda - zrak smo določevali z metodo z nivojsko funkcijo [9], ki je namenjena reševanju problemov s stično površino in se v zadnjih letih veliko uporablja. Pri metodi z nivojsko funkcijo modeliramo medfazno ploskev kot ničelno izohipso f = 0 gladke nivojske funkcije, ki je definirana na celotnem obravnavanem območju kot f(r,t = 0) = ±d(r), kjer je d(r) najmanjša razdalja do medfazne ploskve pri začetnem času t = 0. Glavne lastnosti nivojske funkcije so, da je v področju ene faze pozitivna, v področju druge faze negativna in da je gladka. Časovni razvoj lege medfazne ploskve določujemo z enačbo nivojske funkcije: 2 THE LEVEL-SET METHOD Each phase in the so-defined quasi two-phase flow - the dispersed spheres’ phase and the continuum joint water-air phase - was described using the continuity and momentum equations as explained in [7] and [8]. The water-air surface was determined using the front-capturing level-set method [9], which was developed for free-surface problems and has been widely used in recent years. In the level-set method the phases’ interface is modeled as the zero set f = 0 of a smooth signed normal distance function, defined on the entire physical domain as f(r, t = 0) = ±d(r), where d(r) is the signed minimum distance from the two-fluid interface at the initial time t = 0. The interface position is determined by solving the Hamilton-Jacobi-type level-set equation on the whole domain: VBgfFMK stran 440 Leskovar M. - Mavko B.: Izvirni kombinirani ve~fazni - An Original Combined Multiphase df (v) (1), ki pomika ničelno izohipso nivojske funkcije tako, kakor se premika stična površina. Ker je f gladka funkcija, v nasprotju z gostoto združene faze voda -zrak, ki je na medfazni ploskvi nezvezna, numerično reševanje enačbe nivojske funkcije (1) ni problematično. Gostota združene faze voda - zrak je določena z nivojsko funkcijo kot: which moves the zero level of f in exactly the same way as the actual two-fluid interface moves. Since f is a smooth function, unlike the density of the joint water-air phase, which undergoes a jump at the water-air interface, the level-set equation (1) is more easily solved numerically. The density of the joint water-air phase is determined from the level-set function as: r ( f )=' (rw+ra)/2, f = 0 (2). ra, f<0 Če bi predpis (2) uporabljali dosledno, bi dobili stopničast, nezvezen potek gostote in pojavile bi se nestabilnosti, ki bi bile še posebej izrazite pri velikih razmerjih gostot. Zato je priporočljivo potek gostote na medfazni ploskvi nekoliko zgladiti z: If this prescription (2) were to be used in a straightforward way a graded solution would result and instabilities would occur, especially for large density ratios. Therefore, it is recommendable to smooth the density at the interface as: r (f) rw , ( rw+ra) + ( rw ra ) 2 1 (pf — + — sin ep \ e f>e f\ 10C). povečamo (Cup> 10C). Na sliki 11 je prikazan izračunani The calculated pressure in the water 250 mm above tlak v vodi, 250 mm nad dnom posode, za različne the bottom of the vessel is presented for different vrednosti koeficienta trenja kroglic Cup. S slik 11 in 9 je spheres’ drag coefficients Cup in Figure 11. From Figs. razvidno, da ima koeficient trenja kroglic v najvišji 11 and 9 it is evident that the spheres’ drag coefficient mrežni ravnini prehodne plasti zrak - voda zanemarljiv at the upmost mesh plane of the water-air transition vpliv na rezultate simuliranj, če je dovolj velik (Cu4 layer has a negligible influence on the simulation 10C). Zato smo v našem kombiniranem večfaznem results if it is large enough (Cup > 10C). So, in our | lgfinHi(š)bJ][M]lfi[j;?n 02-8______ stran 445 I^BSSIfTMlGC Leskovar M. - Mavko B.: Izvirni kombinirani ve~fazni - An Original Combined Multiphase modelu za koeficient trenja kroglic v najvišji mrežni ravnini prehodne plasti zrak - voda vzeli naslednjo od velikosti mrežne razdalje odvisno vrednost: combined multiphase model at the upmost mesh plane of the water-air transition layer the following grid-dependent spheres’ drag coefficient was chosen: Cup = 0,01m 10 C Dh (5), ki upošteva dejstvo, da je na gostejši mreži vpliv v eni mrežni ravnini povečanega koeficienta trenja kroglic manjši. 120 ¦ J i 1 K-.V \ \ \ j 100 80 lIpL | j ', '-¦;¦:'. 60 40 20 im lin 0 0 10 20 30 40 0 10 20 30 40 10 20 30 40 1x C 10x C 20x C Sl. 9. Rezultati simuliranj ob času 635 ms za različne vrednosti koeficienta trenja kroglic v najvišji mrežni ravnini prehodne plasti zrak - voda Fig. 9. The simulation results at time 635 ms for different spheres’ drag coefficients at the upmost mesh plane of the water-air transition layer Na sliki 10 so prikazani rezultati simuliranj na mrežah različnih velikostih, opravljenih s spremenjenim koeficientom trenja kroglic (5). Vidimo, da se na vseh mrežah plinski steber razvije tako kakor v preskusih (sl. 3). Na sliki 11 so prikazane še tlačne krivulje, izračunane na mrežah različnih velikosti. Tlačne krivulje so sicer nekoliko odvisne od velikosti mreže tudi na gostejših mrežah (velikost mrež: 1x, 1,5x in 2x), vendar se to zgodi predvsem zaradi velike občutljivosti problema. Tako lahko sklepamo, da je osnovna mreža velikosti 1x z mrežno razdaljo 1 cm primerna za takšne vrste simuliranj. 0,5 0,55 0,6 0,65 0,7 0,75 čas / time (s) 0,8 which takes into account the fact that on a finer grid the influence of the spheres’ drag-coefficient increase in one mesh plane is lower. 0 !|| HI || 'III I 40! 'am&Ml l\\\ s0 l|||sS;|;|i L t li^^""""'"^/^! SJj||l§§§§ ii^vvK^^SK)! t \ww''^-~^z^/yf \\W§LsB%il l!sil=H§! 1 i ^ii^^^t^i'/' t 0 5 10 15 20 10 20 30 40 20 40 60 80 0,5x 1x 2x Sl. 10. Rezultati simuliranj ob času 610 ms na mrežah različnih velikosti, opravljenih s spremenjenim koeficientom trenja kroglic Fig. 10. The simulation results at time 610 ms performed with the modified spheres’ drag coefficient on different mesh sizes The results of the simulations performed with the modified spheres‘ drag coefficient (Eq. 5) on different mesh sizes are presented in Figure 10. It is evident that the gas chimney develops like in the experiments (Fig. 3). The pressure curves calculated on different mesh sizes are presented in Figure 11. The pressure curves are also somewhat grid dependent on the finer meshes (mesh sizes: 1x, 1.5x and 2x), but that is mainly because of the very sensitive nature of the problem. We can conclude that the basic mesh size of 1x with the grid spacing of 1 cm is adequate for this type of simulation. t-------------------------- . -------0.25x -----0.5x -------1x - =2x --------- - ------lC^ " 45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 čas / time (s) Sl. 11. Tlačne krivulje, izračunane za različne vrednosti koeficienta trenja kroglic Cup (leva stran) in na mrežah različnih velikosti (desna stran) Fig. 11. Pressure curves calculated for different spheres’ drag coefficients Cup (left-hand side) and on different mesh sizes (right-hand side) VH^tTPsDDIK stran 446 120 120 100 100 80 60 40 20 20 Leskovar M. - Mavko B.: Izvirni kombinirani ve~fazni - An Original Combined Multiphase Z razvitim kombiniranim večfaznim modelom z ustrezno spremenjenim koeficientom trenja kroglic v najvišji mrežni ravnini prehodne plasti zrak - voda (5) smo ponovno simulirali mešalni preskus Q08. Rezultati simuliranja so predstavljeni v prispevku [8]. 4 SKLEP Predstavili smo novo zasnovo obravnave večfaznih tokov, to je opis s kombiniranim večfaznim modelom, in jo preskusili na primeru izotermnega preskusa mešalne faze eksplozije pare. Ključna zamisel opisa večfaznega toka s kombiniranim večfaznim modelom je, da obravnavamo faze, ki ostanejo ločene s prosto površino (voda in zrak) z modelom proste površine kot eno, združeno fazo z nezveznimi faznimi lastnostmi, medtem ko preostale faze (kroglice) obravnavamo kakor običajno z modelom večfaznega toka. Stično površino (voda - zrak) določamo z nivojsko funkcijo, ki se v zadnjih letih veliko uporablja. Z razvitim izvirnim kombiniranim večfaznim modelom smo simulirali mešalni preskus Q08, ki so ga izvedli na napravi QUEOS. Rezultati simuliranj so pokazali, da se plinski steber, ki nastane med prodiranjem kroglic v vodo, začne zapirati na napačnem mestu na vrhu stebra. Ugotovili smo, da pride do tega zaradi zvezne spremembe gostote na medfazni ploskvi voda - zrak v modelu preskusa, saj je nad čisto fazo vode zaradi opisa s končnimi razlikami vedno prehodna plast z vmesno gostoto. Ta prehodna plast zaduši brizganje vode, do katerega pride pri preskusih med prodiranjem padajočih kroglic v vodo, in povzroči nefizikalno zapiranje zračnega stebra na vrhu. To podedovano numerično pomanjkljivost modela smo odpravili s posebno obravnavo medfaznega trenja kroglic na vodni gladini, na kateri smo koeficient trenja kroglic v najvišji mrežni ravnini prehodne plasti zrak - voda ustrezno povečali in tako dosegli skokovito spremembo medfazne sklopitve gibalne količine kroglic na medfazni ploskvi zrak -voda, tako kakor je to dejansko. Opravljena parametrična analiza je pokazala, da ima koeficient trenja kroglic v najvišji mrežni ravnini prehodne plasti zrak - voda zanemarljiv vpliv na rezultate simuliranj, če je dovolj velik. Tako smo lahko določili optimalno vrednost spremenjenega koeficienta trenja kroglic. Konvergenčna analiza je pokazala, da je mrežna razdalja 1 cm primerna za takšne vrste simuliranj. Zahvala Avtorji se zahvaljujejo Ministrstvu za šolstvo, znanost in šport, ki je finančno podprlo raziskavo v okviru raziskovalnega projekta Z2-3514. With the developed combined multiphase model taking into account the modified spheres’ drag coefficient at the upmost mesh plane of the water-air transition layer (Eq. 5) the premixing experiment Q08 was simulated once again. The results of the simulation were presented in the paper [8]. 4 CONCLUSION A new concept of multiphase flow treatment, the combined multiphase model formulation, was presented and applied to isothermal steam-explosion premixing experiments. The main idea of the combined multiphase model formulation is to treat the phases, which remain separated by a free surface (water and air), with a free-surface model as a single, joint phase with discontinuous phase properties, whereas the other phases (spheres) are treated, as is usual, with a multiphase flow model. The free surface (water-air) is determined with the front-capturing level-set method, which was widely used in recent years. Using the developed, original, combined multiphase model the QUEOS isothermal premixing experiment Q08 was simulated. The simulation results showed that the gas chimney, which forms during the spheres’ penetration into the water, starts to close at the wrong place at the top of the chimney. It was established that this happens because of the gradual change of the density at the water-air surface in the experimental model, since there is always a transition layer with intermediate phases’ density over the pure water phase due to the finite differences’ description. This transition layer chokes the water splashing observed in the experiments and causes the unphysical gas-chimney closing at the top. This inherent deficiency of the numerical model was compensated with a special spheres’ drag treatment at the air-water surface, where the spheres’ drag coefficient at the upmost mesh plane of the water-air transition layer was appropriately increased and so an abrupt rise of the spheres’ interfacial momentum coupling at the water-air surface, as occurs in reality, is achieved. The performed parametric analysis showed that the spheres’ drag coefficient at the upmost mesh point of the water-air transition layer has a negligible influence on the simulation results if it is large enough. So, the optimum value of the modified spheres’ drag coefficient could be established. The convergence analysis showed that a 1-cm grid spacing is appropriate for this kind of simulation. Acknowledgment The authors gratefully acknowledge the support of the Ministry of Education, Science and Sport of the Republic of Slovenia in the frame of the Research Project Z2-3514. | lgfinHi(š)bJ][M]lfi[j;?n 02-8______ stran 447 I^BSSIfTMlGC Leskovar M. - Mavko B.: Izvirni kombinirani ve~fazni - An Original Combined Multiphase [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] 5 LITERATURA 5 REFERENCES Černe, G., I. Tiselj, S. Petelin (2000) Upgrade of the VOF method for the simulation of the dispersed flow. FEDSM 2000, Vol. 251, New York, NY, CD-ROM. Turland, B.D., G.P Dobson (1996) Molten fuel coolant interactions: A state of the art report. European Commission, Nuclear Science and Technology, Luxembourg, ISSN 1018-5593. Leskovar, M., J. Marn (1999) A combined single-multiphase flow formulation of the premixing phase using the level set method. Nuclear Energy in Central Europe ‘99, Portorož, Slovenija, Proceedings, 233-240. Theofanous, T.G., W.W. Yuen, S. Angelini (1999) The verification basis of the PM-ALPHA code. Nuclear Engineering and Design, Vol. 189, 59-102. Tiselj, I., G. Černe (2000) Some comments on the behaviour of the RELAP5 numerical scheme at very small time steps. Nucl. sci. eng, Vol. 134, 306-311. Leskovar, M., J. Marn, B. Mavko (2000) Numerical analysis of multiphase mixing - comparison of first and second order accurate schemes. Fluid Mechanics Research, Vol. 27, 1-32. Marn, J., M. Leskovar (1996) Simulation of steam explosion premixing phase using probabilistic multiphase flow equations. Fluid Mechanics Research, Vol. 22 (1), 44-55. Leskovar, M., B. Mavko (2002) Simuliranje izotermnega QUEOS preskusa mešalne faze eksplozije pare Q08. Strojniški vestnik, Vol. 48(2002)8, 449-458. Sethian, JA. (1998) Level set methods. Cambridge University Press, Cambridge. Meyer, L., G. Schumacher (1996) QUEOS, a simulation-experiment of the premixing phase of a steam explosion with hot spheres in water, base case experiments. FZKA Report 5612, Forschungszentrum Karlsruhe. Leskovar, M., J. Marn, B. Mavko (2000) The influence of the accuracy of the numerical methods on steam-explosion premixing-phase simulation results. Journal of Mechanical Engineering, Vol. 46, 607-621. Naslov avtorjev: dr. Matjaž Leskovar profdr. Borut Mavko Institut “Jožef Stefan” Jamova 39 1000 Ljubljana matjaz.leskovar@ijs.si borut.mavko@ijs.si Authors’ Address: Matjaž Leskovar Borut Mavko “Jožef Stefan” Institute Jamova 39 1000 Ljubljana, Slovenia matjaz.leskovar@ijs.si borut.mavko@ijs.si Prejeto: Received: 6.8.2001 Sprejeto: Accepted: 20.9.2002 VH^tTPsDDIK stran 448 © Strojni{ki vestnik 48(2002)8,449-458 © Journal of Mechanical Engineering 48(2002)8,449-458 ISSN 0039-2480 ISSN 0039-2480 UDK 004.94:532.5:536.7 UDC 004.94:532.5:536.7 Izvirni znanstveni ~lanek (1.01) Original scientific paper (1.01) Simuliranje izotermnega QUEOS preskusa me{alne faze eksplozije pare Q08 Simulation of the Isothermal QUEOS Steam-Explosion Premixing Experiment Q08 Matja` Leskovar - Borut Mavko Mešalna faza eksplozije pare obsega interakcijo curka taline z vodo pred izbruhom eksplozije pare. Da bi bolje spoznali hidrodinamične procese med mešalno fazo eksplozije pare, izvajajo poleg “vročih” preskusov, pri katerih je pomembno uparjanje vode, tudi “hladne” izotermne preskuse. Značilnost izotermnih preskusov mešalne faze eksplozije pare je, da se od vseh treh faz, to je vode, zraka in kroglic, z drugima dvema fazama pomešajo le kroglice, medtem ko ostaneta voda in zrak ločena z gladko medfazno ploskvijo. To dejstvo smo upoštevali pri razvoju izvirnega kombiniranega večfaznega modela mešalne faze eksplozije pare. Pri razvitem kombiniranem večfaznem modelu obravnavamo vodo in zrak z modelom proste površine kot eno, združeno fazo z nezveznimi faznimi lastnostmi na medfazni ploskvi voda -zrak, kroglice pa obravnavamo kot običajno z modelom večfaznega toka, pri katerem pomenijo kroglice razpršeno fazo, združena faza voda - zrak pa kontinuum, ki obdaja kroglice. Razviti kombinirani večfazni model smo preverili na izotermnem preskusu Q08, ki so ga izvedli na napravi QUEOS. Simuliranja smo opravili z različnimi numeričnimi obravnavami medfazne ploskve voda -zrak (metoda z nivojsko funkcijo, metoda visoke ločljivosti, metoda “nazaj”) za nestisljiv in stisljiv primer. Rezultate simuliranj smo primerjali med seboj in s podatki preskusa. © 2002 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: tok večfazni, modeli večfazni, eksplozija parne, metode z nivojsko funkcijo, simuliranje) The premixing phase of a steam explosion covers the interaction of the melt jet with the water prior to any steam explosion occurring. To get a better insight into the hydrodynamic processes during the premixing phase, in addition to “hot” premixing experiments, where the water evaporation is significant, “cold” isothermal premixing experiments were also performed. The special feature of isothermal premixing experiments is that three phases are involved - the water, the air and the spheres ’ phase - but only the spheres’ phase mixes with the other two phases, whereas the water and air phases do not mix and remain separated by a free surface. Our idea was to treat the isothermal premixing process with an original, combined multiphase model. In the developed combined multiphase model the water and air phases are treated with a free-surface model as a single, joint phase with discontinuous phase properties at the water-air interface. The spheres are treated, as is usual, with a multiphase flow model, where the spheres represent the dispersed phase and the joint water-air phase represents the continuous phase. The developed combined multiphase model was validated against the QUEOS isothermal premixing experiment Q08. A numerical analysis using different treatments of the water-air interface (level set, high-resolution, upwind) was performed for the incompressible and compressible cases and the results were compared with experimental measurements. © 2002 Journal of Mechanical Engineering. All rights reserved. (Keywords: multiphase flow, multiphase models, steam explosion, level set methods, simulations) 0 UVOD Med resno nezgodo v jedrski elektrarni, ko pride staljena sredica po različnih poteh v stik s hladilno vodo, lahko pride do eksplozije pare. Eksplozijo pare razdelimo na več faz. Prva, mešalna faza eksplozije pare je najbolj pomembna, ker določa začetne pogoje morebitne eksplozije pare in podaja 0 INTRODUCTION During a severe reactor accident following core meltdown when the molten fuel comes into contact with the coolant water a steam explosion may occur. A steam explosion can be divided into more stages. The first stage, called premixing, is the most important since it provides the initial conditions for a possible steam explosion and gfin^OtJJIMISCSD 02-8 stran 449 |^BSSITIMIGC Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal največjo količino staljenega jedrskega goriva, ki bi lahko sodelovalo pri eksploziji. Da bi bolje spoznali hidrodinamične procese med prodiranjem taline v vodo, izvajajo poleg “vročih” preskusov, pri katerih je pomembno predvsem uparjanje vode, tudi “hladne” izotermne preskuse. Pri teh izotermnih preskusih mešalne faze eksplozije pare spuščajo različne curke hladnih kroglic v posodo, napolnjeno z vodo in opazujejo dogajanja [1]. Značilnost izotermnih preskusov mešalne faze eksplozije pare je, da se od prisotnih treh faz, to je vode, zraka in kroglic, s preostalima dvema fazama pomešajo le kroglice, medtem ko ostaneta voda in zrak ločena z gladko medfazno ploskvijo. To dejstvo smo upoštevali pri razvoju izvirnega kombiniranega večfaznega modela mešalne faze eksplozije pare. Pri razvitem kombiniranem večfaznem modelu obravnavamo vodo in zrak z modelom proste površine kot eno, združeno fazo z nezveznimi faznimi lastnostmi na medfazni ploskvi voda - zrak, kroglice pa obravnavamo kot običajno z modelom večfaznega toka, pri katerem pomenijo kroglice razpršeno fazo, združena faza voda - zrak pa kontinuum, ki obdaja kroglice [2]. 1 GLAVNE ENAČBE determines the maximum quantity of melt, which might then be involved in the explosion. To investigate the mixing process associated with the melt penetration, in addition to “hot” premixing experiments, where the water evaporation is significant, “cold” isothermal premixing experiments were also performed to get a better insight into the hydrodynamic processes during the premixing phase. In these isothermal premixing experiments, different jets of spheres are injected in a water pool [1]. The special feature of isothermal premixing experiments is that three phases are involved – the water, the air and the spheres’ phase – but only the spheres’ phase mixes with the other two phases, whereas the water and air phases do not mix and remain separated by a free surface. Our idea was to treat the isothermal premixing process with an original combined multiphase model. In the developed combined model the water and air phases are treated with a free-surface model as a single, joint phase with discontinuous phase properties at the water-air interface. The spheres are treated, as is usual, with a multiphase flow model, where the spheres represent the dispersed phase and the joint water-air phase represents the continuous phase [2]. 1 GOVERNING EQUATIONS Fazna verjetnost a in gostota p združene faze voda - zrak c sta definirani kot: The phase presence probability a and the density pc of the joint water-air phase c are defined as: ac=aw+aa, Pc= a^+a^ (1), kjer indeksa w in a označujeta fazi vode in zraka. S to definicijo lahko večfazen tok kroglic, vode in zraka obravnavamo kot navidez dvofazen tok razpršenih kroglic d v kontinuumu združene faze voda - zrak c. Vsako fazo p v tako definiranem navidez dvofaznem toku smo opisali s kontinuitetno: where the indices w and a correspond to the water and air phases. With this definition the multiphase flow of spheres, water and air can be described as a quasi two-phase flow of dispersed spheres d in the continuous joint water-air phase c. Each phase p in the so-defined quasi two-phase flow is described using the continuity: Lt (apPp)+V-(apPpvp)=0 in gibalno enačbo: and the momentum equation: dt (2) (3), ki smo ju izpeljali s statističnim povprečenjem enofaznih enačb [3]. Pri tem smo medfazno sklopitveno silo M definirali kot: obtained by ensemble averaging the single-phase r equations [3]. The interfacial friction force M is defined as: Md=M drag + Mvd m+Mldift, acMc=-ad M kjer silo medfaznega trenja računamo z [4]: Mdd r ag = 0, 44 3 c 4 d d silo navidezne mase z [4]: where the drag force is calculated from [4]: v c - v d l(v c - v d ) the virtual mass force from [4]: (4), (5), VBgfFMK stran 450 Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal M vm =0.5r I Dv r c - D v r d in dvižno silo z [4]: c| Dt Dt and the lift force from [4]: Mldift =0.5rc ( vc-v )x(Vxvc (6) (7). Medfazno trenje kroglic na medfazni ploskvi The spheres’ drag at the water-air surface was voda - zrak smo določevali na poseben način, ki upošteva treated in a special way by considering the nezveznost prehoda zrak - voda, kakor je opisano v [5]. discontinuous air-water transition as described in [5]. Tlačno enačbo za predpostavljeno skupno The pressure equation for the assumed tlačno polje p smo izpeljali iz vsote kontinuitetne common pressure field p was derived from the sum of enačbe za stisljivo tekočino (2) po vseh fazah s the compressible flow continuity equation (2) over projekcijsko metodo [6]: all phases using the projection method [6]: kjer je: I p rp( pn+1-pn ) +v-( apn+1 r np+1/ 2 ) Dt-v- rp dpn an+1 p Vpn+1 vr n+1/ 2 = vr n + Dt where: ( vnp-v) vnp+g+ rp Mnp rp n+1/ 2 Dt J J r np+1/ 2 =r(apn+1 ,p n ) (8), (9). 2 SIMULIRANJA PRESKUSA MEŠALNE FAZE Za analizo izvirnega kombiniranega večfaznega modela smo izbrali preskus mešalne faze Q08, ki so ga izvedli na napravi QUEOS [7]. Pri tem preskusu so spuščali molibdenove kroglice premera 4,2 mm in skupne mase 10 kg z višine 1,3 m skozi cev v posodo v obliki kvadra z osnovno ploskvijo 70 cm x 70 cm in višino 138 cm, napolnjeno z vodo. Premer curka kroglic je bil 18 cm, hitrost kroglic na vodni gladini 5,12 m/s in fazna verjetnost kroglic 0,17. Višina vodne gladine v posodi je bila 100 cm, začetni tlak plina nad vodno gladino pa 0,975 bar. Pri simuliranjih preskusa smo obravnavali le z vodo napolnjeni spodnji del posode in 20 cm debelo plast plina nad vodno gladino (sl. 1). Vse druge značilnosti preskusa smo upoštevali z ustreznimi robnimi pogoji. Predpostavili smo, da je plin nad vodno gladino zrak. V resnici je plin v posodi neznana mešanica vodne pare in neukapljivega argona. Simuliranja smo opravili v valjnem koordinatnem sistemu ob predpostavki osne simetričnosti problema. Ta predpostavka je le delno upravičljiva, saj porazdelitev kroglic predvsem na čelu curka ni osno simetrična zaradi sprostilnega mehanizma kroglic, pri katerem se simetrično odpreta dve ravni premični plošči [8]. Dejanski polmer valjaste posode modela (41 cm) smo določili tako, da sta se ujemali površini osnovnih ploskev modela in preskusa. Padajoči curek kroglic smo v model vključili z robnimi pogoji (RP). Robne vrednosti hitrostnega polja kroglic v in polja fazne verjetnost kroglic a na zgornjem robu simulirnega območja 20 cm nad vodno gladino smo določili posredno iz znanih 2 SIMULATIONS OF THE PREMIXING EXPERIMENT The QUEOS premixing experiment Q08 was chosen for the analysis of the original combined multiphase model [7]. In this experiment molybdenum spheres with a diameter of 4.2 mm and a total mass of 10 kg were discharged from a height of 1.3 m through a tube into a water-filled vessel with an inner cross-section of 70 cm x 70 cm and a height of 138 cm. The spheres’ jet diameter was 18 cm and the spheres entered the water at a velocity of 5.12 m/s and a phase-presence probability of 0.17. The water level in the vessel was 100 cm, and the initial gas pressure over the water surface was 0.975 bar. In the experimental simulations only the part of the vessel filled with water together with a 20-cm-wide gas zone over the water surface was modeled (Figure 1). All other experimental features were taken into account with appropriate boundary conditions. It was assumed that the gas over the water was air. In fact it was an unknown mixture of steam and non-condensable argon. The simulations were performed in the cylindrical coordinate system and assumed an axial symmetry for the problem. This was not really the case in the experiment since the release mechanism with two doors opening in opposite directions caused, especially at the front of the spheres’ cloud, an initially non- axially symmetric distribution of the falling spheres [8]. To match the cross-sectional area of the vessel, an equivalent radius of 41 cm was used in the axially symmetric model. The falling spheres were introduced in the model with boundary conditions (BCs). The appropriate boundary conditions for the spheres’ velocity vz and the spheres’ presence probability as at the upper edge of the simulation region 20 cm above the water surface were | IgfinHŽšlbJlIMlIgiCšD I stran 451 glTMDDC Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal 9 cm curek kroglic spheres jet zrak air vodna gladina water surface voda water simetrijska os symmetry axis robni pogoji / boundary conditions: vz = 4,72 m/s as = 0,184 D t = 0,0443 s p = 0,975 bar 20 cm 100 cm 41 cm Sl. 1. Shema modela QUEOS preskusa Q08 Fig. 1. Schematic model of QUEOS experiment Q08 povprečnih vrednosti na vodni gladini. Čas preleta curka kroglic Dt mimo zgornjega roba simulirnega območja smo določili iz razmerja znane celotne mase kroglic in izračunanega masnega toka kroglic [2]. Polja faznih verjetnosti in hitrostna polja faz smo računali z metodo velike ločljivosti [9], ki je drugega reda natančnosti. Metoda velike ločljivosti je temeljila na privetrni metodi prvega reda natančnosti in metodi Lax-Wendroff, ki je drugega reda natančnosti [10]. Tlačno enačbo smo reševali z metodo CGSTAB [6], ker hitro konvergira tudi za velika razmerja gostot posameznih faz [8]. Nezvezno gostoto združene faze voda - zrak smo določevali z metodo z nivojsko funkcijo [11], katero so razvili za reševanje problemov s prosto površino in se v zadnjih letih veliko uporablja. Simuliranja preskusov smo opravili na mreži velikosti 41 x 120 točk. Tako je bila mrežna razdalja točno 1 cm, kar je, kakor je pokazala konvergenčna analiza, primerno za takšne vrste simuliranj [5]. 3 REZULTATI SIMULIRANJ determined from the known average values at the water’s surface. The time interval Dt during which the spheres were falling through the upper boundary of the simulated region was established from the total spheres’ mass and the calculated spheres’ mass-flow rate [2]. The phases’ presence probabilities and the phases’ velocities were calculated using the second-order-accurate high-resolution method [9]. The high-resolution method was based on the first-order-accurate upwind method and the second-order-accurate Lax-Wendroff method [10]. The pressure equation was solved using the CGSTAB method [6], since it also converges quickly for high phase-density ratia [8]. The discontinuous density of the joint water-air phase was determined with the front-capturing level-set method [11], which was developed for free-surface problems and has been widely used in recent years. The experimental simulations were performed on a mesh with 41 x 120 grid points. The grid spacing was exactly 1 cm, which is adequate for this type of simulation, as the convergence analysis showed [5]. 3 RESULTS OF THE SIMULATIONS Da bi bolje spoznali prednosti razvitega To get a better insight into the advantages of kombiniranega večfaznega modela, pri katerem the developed combined multiphase model with the VH^tTPsDDIK stran 452 Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal obravnavamo medfazno ploskev voda - zrak z metodo z nivojsko funkcijo (NF - LS), ki so jo razvili za reševanje problemov s stično površino, smo medfazno ploskev voda - zrak primerjalno določevali še z metodo velike ločljivosti (VL - HR), ki je drugega reda natančnosti, in privetrno metodo (PM - UW) prvega reda natančnosti. Na sliki 2 so prikazani posnetki preskusa Q08, ki so jih napravili s hitro slikovno kamero ob osvetlitvi z zadnje strani. Čas posnetkov je merjen od sprostitve kroglic. Ker točni podatki niso bili na voljo, smo lahko čas posnetkov določili le približno. Na slikah je vidna referenčna mreža s celicami velikosti 10 cm x 10 cm, ki je pritrjena na notranjo stran okenskih šip posode. Ker so okna široka le 50 cm, je na vsaki strani in tudi na dnu posode zakrit 10 cm širok pas. Poudariti je treba, da pomeni večji del črno senčenega območja na posnetkih plinski steber in ne kroglic. incorporated level-set (LS) method, which was developed for free-surface problems, the water-air surface was, for a comparison, also determined with the second-order-accurate high-resolution (HR) method and the first-order-accurate upwind (UW) method. The images of experiment Q08 taken with a high-speed film camera with backlighting are presented in Figure 2. The time, which is measured after the release of the spheres, could only be determined approximately since no exact data was available. On the images the 10 cm x 10 cm reference grid mounted close to the inside of each of the vessel windows can be seen. Since the windows are only 50-cm wide, there is a 10-cm-wide zone on both sides and also on the bottom of the vessel, which is hidden. It should be stressed that most of the black shaded region on the images represents the gas chimney and not the spheres. -TTT T H----- J t =~520 ms t =~590 ms t =~650 ms t =~725 ms t =~775 ms Sl. 2. Posnetki preskusa Q08, napravljeni ob različnih časih (posnetki vzeti iz [7]) Fig. 2. Images of experiment Q08 taken at different times (images taken from [7]) Na slikah 3 do 5 so predstavljeni rezultati simuliranj, opravljenih z metodami NF, VL in PM. Slike prikazujejo gostoto združene faze voda - zrak (črni obrisi), fazno verjetnost kroglic (sivi obrisi) in hitrostno polje združene faze voda - zrak v valjnem koordinatnem sistemu (r, z) v ekvidistančnih 50 ms dolgih časovnih razmikih Čas je zaradi lažje primerjave merjen tako kakor pri preskusu po sprostitvi kroglic, to je 0,46 s pred začetkom simuliranja. Obrisi gostote združene faze voda - zrak (p = 997 kg/m3, p = 1,2 kg/m3) imajo vrednosti 2, 100 w 200, ..., 800, 900, 996 kg/m3, obrisi fazne verjetnosti kroglic pa imajo vrednosti 0,02; 0,05; 0,1; 0,15; itn. Hitrostno polje je predstavljeno z enotskimi vektorji, ki prikazujejo le smer vektorja hitrosti in ne tudi velikosti hitrosti, saj bi bile sicer slike nepregledne. Kakor smo pričakovali, ostane medfazna ploskev voda - zrak ostra med celotnim simuliranjem le pri izračunu z metodo NF. Pri metodi VL, ki je drugega reda natančnosti, predvsem pa pri metodi PM prvega The results of the simulations performed with the LS, HR and UW methods are presented in Figs. 3 to 5. The figures show the joint water-air phase density (black contours), the spheres’ presence probability (gray contours) and the joint water-air phase velocity field in the cylindrical coordinate system (r, z) in equidistant 50-ms-long time intervals. The time is measured, as in the experiment, after the release of the spheres, i.e. 0.46 s before the start of the simulation. The joint water-air phase density (rw = 997 kg/m3, ra = 1.2 kg/m3) contours correspond to values 2, 100, 200, ... , 800, 900, 996 kg/m3, and the spheres’ presence probability contours correspond to the values 0.02, 0.05, 0.1, 0.15, etc. The velocity field is represented by unit vectors showing only the direction of the velocity vector but not the speed because the figures would be unclear. As expected, the water-air surface remains sharp during the whole simulation only during the LS-method calculation. For the second-order-accurate HR method, and in particular for the first-order- gfin^OtJJlMISCSD 02-8 stran 453 |^BSSITIMIGC Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal reda natančnosti, se združena faza voda - zrak nefizikalno razprši zaradi numerične difuzije. Numerična difuzija je splošna skupna pomanjkljivost metod končnih razlik. Rezultati simuliranj, opravljenih z metodo NF (slika 3), se kakovostno razmeroma dobro ujemajo s posnetki preskusa (sl. 2). t = 560 ms t = 610 ms accurate UW method, the joint water-air phase unphysically mixes due to numerical diffusion, which is a common weakness of finite-differences methods. The simulation results performed with the LS method (Figure 3) agree qualitatively quite well with the images of the experiment (Figure 2). \\\\\wm\\\ 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 t = 660 ms t = 710 ms 0 10 20 30 40 t = 760 ms Sl. 3. Gostota združene faze voda - zrak, fazna verjetnost kroglic in hitrostno polje združene faze voda - zrak ob različnih časih pri izračunih z metodo NF Fig. 3. The joint water-air phase density, the spheres’ phase-presence probability and the joint water-air phase velocity field at different times for the LS-method calculation {\\\\\w,m\\ t = 560 ms 0 10 20 30 40 0 10 20 30 40 t = 610 ms 0 10 20 30 40 t = 660 ms t = 710 ms 0 10 20 30 40 0 10 20 30 40 t = 760 ms Sl. 4. Gostota združene faze voda - zrak, fazna verjetnost kroglic in hitrostno polje združene faze voda - zrak ob različnih časih pri izračunih z metodo VL Fig. 4. The joint water-air phase density, the spheres’ phase-presence probability and the joint water-air phase velocity field at different times for the HR-method calculation VH^tTPsDDIK stran 454 120 120 120 120 120 100 100 100 100 100 80 80 80 80 80 60 60 60 60 60 40 40 40 40 40 20 20 20 20 20 0 0 0 0 120 100 80 60 40 20 0 Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 t = 560 ms t = 610 ms t = 660 ms t = 710 ms t = 760 ms Sl. 5. Gostota združene faze voda - zrak, fazna verjetnost kroglic in hitrostno polje združene faze voda - zrak ob različnih časih pri izračunih z metodo PM Fig. 5. The joint water-air phase density, the spheres’ phase-presence probability and the joint water-air phase velocity field at different times for the UW-method calculation Pri vseh simuliranjih smo spremljali tudi potek tlaka na različnih globinah. Na sliki 6 so prikazane izračunane tlačne krivulje skupaj s preskusnimi podatki. Tlaka p3 in p6 so merili v vodi ob steni posode v točkah 838 mm in 250 mm nad dnom posode. Porast tlaka 0,5 s po izpustu kroglic označuje začetek prodiranja čelnih kroglic v vodo, tlačni vrh po 0,76 s pa zapiranje plinskega stebra. Pri prvem nizu simuliranj smo vse tri faze, to je vodo, zrak in kroglice, obravnavali kot nestisljive. Kakor je razvidno s slike 6, se ob zapiranju plinskega stebra pojavi tlačna konica, ki je najbolj izrazita pri izračunu z metodo NF, pri kateri ostane medfazna ploskev voda - zrak ostra, medtem ko se tlačna nihanja, ki se pojavijo pri preskusu, ne razvijejo. To kakovostno drugačno obnašanje tlaka kakor pri preskusu je posledica nestisljive obravnave zraka, saj je razlog za tlačna nihanja pri preskusu širjenje in krčenje velikega plinskega mehurja, ki se oblikuje po zaprtju plinskega stebra. V drugem nizu simuliranj smo zato fazo zraka obravnavali kot stisljivo. Ker energijske enačbe nismo vključili v model, je bilo treba za stisljivost zraka določiti ustrezno vrednost. Stisljivost zraka je omejena z največjo, izotermno stisljivostjo in najmanjšo, adiabatno stisljivostjo. Preprosta ocena pokaže, da je prevod toplote v plinski mehur v enem nihajnem času zanemarljiv in da je zato adiabatna stisljivost zraka zelo dober približek: During all the simulations the pressure at different levels was also traced. The calculated pressure curves are presented together with the experimentally measured values in Fig. 6. The pressures p3 and p6 were measured in the water at the vessel’s wall, 838 mm and 250 mm from the bottom of the vessel. The pressure rise 0.5 s after the spheres’ release indicates the entry of the first spheres into the water and the pressure peak after 0.76 s is the collapse of the gas chimney. In the first set of simulations, all three phases – the water, the air and the spheres’ phase – were treated as incompressible. As seen in Fig. 6, the pressure produces a spike when the gas chimney collapses, most pronounced for the LS method, where the water-air surface remains sharp, whereas the pressure oscillations, which were observed in the experiment, do not occur. This qualitatively different pressure behavior is due to the incompressible air treatment, since the reason for the pressure oscillations in the experiment is the expansion and compression of the whole, big, gas bubble, which forms after the gas-chimney collapse. In the second series of simulations the air phase was therefore treated as compressible. Since the energy equation was not taken into account the correct air compressibility, which lies somewhere in the range bounded with the maximum isothermal and minimum adiabatic value, had to be determined. A simple estimation shows that the heat conduction in the gas bubble during one oscillation period is negligible and that, consequently, the adiabatic air compressibility is a very good approach: DT la Dto DT a = a Dt osc 10-2W/Km-10-1s 1kg/m3-103J/kgK.10-2m =10-4 <<1 (10), | IgfinHŽšlbJlIMlIgiCšD I stran 455 glTMDDC 120 120 120 120 120 100 100 100 100 100 80 80 80 80 80 60 60 60 60 60 40 40 40 40 40 20 20 20 20 20 0 0 0 0 2 Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal kjer so: AT razlika temperature zraka v mehurju in temperature okolišne vode, AT sprememba temperature zraka v mehurju v enem nihajnem času At zaradi prevoda toplote in Ala linearna izmera mehurja. Kljub temu smo simuliranja opravili tudi z izotermno stisljivostjo zraka, predvsem zato, da bi spoznali vpliv stisljivosti zraka na rezultate simuliranj. Na sliki 6 je prikazan potek tlaka za oba stisljiva primera, pri katerih upoštevamo izotermno oz. adiabatno stisljivost zraka. Kakor smo pričakovali, se v stisljivih primerih pojavijo tlačna nihanja. Tlačna nihanja so najbolj izrazita pri metodi NF, pri kateri ostane medfazna ploskev voda - zrak ostra. nestisljivo / incompressible 1,35 1,3 1,25 1,2 1,15 1,1 1,05 1 Q08-p6 Q08-p3 LS-p6 LS-p3 HR-p6 HR-p3 UW-p6 UW-p3 where AT is the temperature difference between the air in the bubble and the surrounding water, AT is the temperature change of the air in the bubble during one oscillation period At due to heat conduction and Al is the linear dimension of the bubble. Despite that the simulations were also performed with the isothermal air compressibility, primarilly to establish the air compressibility’s influence on the simulation results. The pressure behavior in the compressible cases taking into account the isothermal and adiabatic air compressibility are presented in Fig. 6. As expected, in the compressible cases the pressure oscillations occur and are most pronounced for the LS method, where the water-air surface remains sharp. stisljivo - izotermno / compressible - isothermal --------------------------------- - - - - Q08-p6 Q08-p3 LS-p6 LS-p3 HR-p6 HR-p3 UW-p6 UW-p3 0,5 0,55 0,8 0.5 0,6 0,65 0,7 0, čas / time (s) stisljivo - adiabatno / compressible - adiabatic 1,25 --------------------------------------------------------------------------------------- 0.55 0.6 0.65 čas / time (s) 0.7 0.75 0.8 1,2 1,15 - 1,1 1,05 -¦ 1 -- 0,95------ 0,45 Q08-p6 Q08-p3 LS-p6 LS-p3 HR-p6 HR-p3 UW-p6 UW-p3 A 0,5 0,55 0,7 0,75 0,8 0,6 0,65 čas / time (s) Sl. 6. Primerjava tlakov na različnih globinah (p3 in p6) pri izračunih z metodami NF, VL in PM za nestisljivo, izotermno in adiabatno stisljivost zraka s podatki preskusa Q08 Fig. 6. Comparison of pressures in the vessel at different levels (p3 and p6) between LS-, HR- and UW- methods calculations for the incompressible, isothermal and adiabatic air compressibility and the experimental measurements Q08 Da bi simuliranja lažje primerjali med seboj, smo glavne rezultate simuliranj zbrali v preglednici 1. Za vsa predstavljena simuliranja so navedeni naslednji podatki: največji tlak p6 (p ), čas po katerem tlak doseže vrh (t ) in časovni razmik med prvim tlačnim vrhom in dolom pri tlačnem nihanju (At c/2). Zaradi popolnosti in kot referenca so dodane tudi preskusne vrednosti, ki pa niso namenjene za resno primerjavo, saj so bile preskusne razmere, kar je opisano v 2. poglavju, nekoliko drugačne. Potek tlaka se pri izračunih z metodami PM, VL in NF razlikuje zaradi različno izrazite razpršitve medfazne ploskve voda - zrak, ki jo povzročajo te numerične metode. Metoda PM prvega reda natančnosti povzroči največjo razpršitev (sl. 5) in zato To make the comparison of the simulations easier the main results are assembled in table 1. The maximum pressure p6 (pmax), the time when the pressure peak is reached (tpmax) and the time between the first pressure maximum and minimum during the pressure oscillations (Dtosc/2) are listed for all the presented simulations. The experimental values are also added for completeness and as a reference, but not for a rigorous comparison since the experimental conditions were somewhat different, as explained in section 2. The reason for the various pressure behaviors for the UW-, HR- and LS-method calculations is the different extent of water-air surface-spreading these numerical methods produce. The first-order-accurate UW method produces the highest spreading (Fig. 5), so the VH^tTPsDDIK stran 456 Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal Preglednica 1. Glavni rezultati nestisljivih in stisljivih simuliranj, opravljenih z metodami NF, VL in PM, skupaj s podatki preskusa Q08 Table 1. Main results of the incompressible and compressible simulations performed with the LS-, HR- and UW-methods together with the experimental measurements Q08 pmax (ba t p max (s) ) — &tosc/2(s) nestisljivo incompressible NF/LS VL/HR PM/UW NF/LS VL/HR PM/UW 1,328 1,098 1,060 1,143 1,108 1,067 J----- Simuliranje Simulation stisljivo - izotermno compressible - isothermal 0,740 0,730 0,716 0,756 0,747 0,725 0,031 0,032 0,036 stisljivo - adiabatno compressible - adiabatic NF/LS 1,155 0,753 0,027 VL/HR 1,111 1,066 1,219 0,028 PM/UW 0,743 0,720 0,760 0,028 preskus experiment Q08 0,030 se začne zračni steber najhitreje zapirati. Ker se gostota medfazne ploskve voda - zrak spreminja najpočasneje, je povišanje tlaka najmanjše. Pri metodi VL je medfazna ploskev voda - zrak ostrejša (sl. 4) in zato je amplituda tlačnih nihanj večja. Tlačne spremembe so največje pri metodi NF, saj ostane medfazna ploskev voda - zrak ostra med celotnim simuliranjem (sl. 3), tako kakor je vidno tudi na posnetkih preskusa (sl. 2). Kakor smo pričakovali, vpliva stisljivost zraka neposredno na frekvenco tlačnih nihanj. Pri manjši, adiabatni stisljivosti zraka je frekvenca tlačnih nihanj višja (preglednica 1). 4 SKLEP Predstavili smo izvirno obravnavo izotermnih preskusov mešalne faze eksplozije pare. Značilnost izotermnih mešalnih preskusov je, da jih ni mogoče ustrezno obravnavati niti izključno z modeli proste površine niti izključno z modeli večfaznega toka, saj se kroglice razpršijo, medtem ko ostane medfazna ploskev voda - zrak ostra. Zato smo se odločili razviti kombinirani večfazni model, pri katerem kroglice kot običajno obravnavamo z modelom večfaznega toka, medfazno ploskev voda - zrak pa z modelom proste površine. Izvirni kombinirani večfazni model smo preverili na izotermnem preskusu mešalne faze eksplozije pare Q08, ki so ga izvedli na napravi QUEOS. Opravili smo številna primerjalna simuliranja, pri katerih smo medfazno ploskev voda - zrak določevali z različnimi numeričnimi postopki (NF, VL in PM), pri tem pa zrak obravnavali kot stisljiv oz. nestisljiv Po pričakovanju so rezultati simuliranj pokazali, da ostane medfazna ploskev voda - zrak ostra le pri izračunih z metodo NF in da je razpršitev medfazne ploskve voda - zrak največja pri izračunih z metodo PM prvega reda natančnosti. Posledično so tlačne spremembe največje pri metodi NF, kjer se gostota na medfazni ploskvi voda - zrak najhitreje spremeni. Tlačna nihanja, ki so se pojavila pri preskusu, smo dobili le v stisljivem primeru, saj so posledica nihanja ujetega plinskega mehurja. Ob upoštevanju predstavljenih pomanjkljivosti modela air chimney starts to close the fastest in this calculation. Since the density of the spread water-air surface changes slowest the pressure rise is the lowest. The HR method produces a sharper water-air interface (Fig. 4); therefore, the amplitude of the pressure oscillations is greater. The pressure changes are the largest for the LS method since it keeps the water-air interface sharp during the whole simulation (Fig. 3), as was also observed in the experiment (Fig. 2). As expected, the air compressibility has a direct influence on the pressure oscillation frequency. At the lower adiabatic air compressibility the pressure oscillation frequency is higher (Table 1). 4 CONCLUSION An original treatment of isothermal steam-explosion premixing experiments was presented. The special feature of isothermal premixing experiments is that they cannot be adequately modeled just with free-surface models or just with multiphase flow models, since the spheres disperse, whereas the water-air surface remains sharp. So we decided to develop a combined multiphase model, where the spheres are treated, as is usual, with a multiphase flow model, whereas the water-air surface is treated with a free-surface model. The original combined multiphase model was validated using the QUEOS isothermal premixing experiment Q08. A number of simulations were performed in a comparison using different numerical methods for the water-air surface determination (LS, HR and UW) treating the air as compressible or incompressible. As expected, the results of the simulations showed that the water-air surface remains sharp only for the LS-method calculations and that the first-order-accurate UW method produces the highest water-air surface spreading. Consequently, the pressure variations are the largest for the LS method, where the density at the water-air interface changes most rapidly. The pressure oscillations that were observed in the experiment could only be reproduced in the compressible case since they are the consequence of the entrapped gas bubble oscillations. The simulation results obtained with the LS gfin^OtJJlMISCSD 02-8 stran 457 |^BSSITIMIGC Leskovar M. - Mavko B.: Simuliranje izotermi~nega - Simulation of an Isothermal preskusa, se rezultati simuliranj z metodo NF tako kakovostno kakor količinsko dobro ujemajo s podatki preskusa. Zahvala Avtorji se zahvaljujejo Ministrstvu za šolstvo, znanost in šport, ki je finančno podprlo raziskavo v okviru raziskovalnega projekta Z2-3514. method agree, when the deficiencies of the presented experiment model are considered, qualitatively and quantitatively well with the experimental measurements. Acknowledgment The authors gratefully acknowledge the support of the Ministry of Education, Science and Sport of the Republic of Slovenia in the frame of the Research Project Z2-3514. 5 LITERATURA 5 REFERENCES [I] Turland, B.D., G.P. Dobson (1996) Molten fuel coolant interactions: A state of the art report. European Commission, Nuclear Science and Technology, Luxembourg, ISSN 1018-5593. [2] Leskovar, M., J. Marn (1999) A combined single-multiphase flow formulation of the premixing phase using the level set method. Nuclear Energy in Central Europe ‘99, Portorož, Slovenija, Proceedings, 233-240. [3] Marn, J., M. Leskovar (1996) Simulation of steam explosion premixing phase using probabilistic multiphase flow equations. Fluid Mechanics Research, Vol. 22 (1), 44-55. [4] Fletcher, D.F, P.J. Witt (1996) Numerical studies of multiphase mixing with application to some small-scale experiments. Nuclear Engineering and Design, 135-145. [5] Leskovar, M., B. Mavko (2002) Izviren kombiniran večfazni model mešalne faze eksplozije pare. Strojniški vestnik, Vol. 48(2002)8,438-448. [6] Ferziger, J.H., M. Peric (1996) Computational Methods for Fluid Dynamics. Springer-Verlag, Berlin, Heidelberg. [7] Meyer, L., G. Schumacher (1996) QUEOS, a simulation-experiment of the premixing phase of a steam explosion with hot spheres in water, base case experiments. FZKA Report 5612, Forschungszentrum Karlsruhe. [8] Leskovar, M., J. Marn, B. Mavko (2000) The influence of the accuracy of the numerical methods on steam-explosion premixing-phase simulation results. Journal of Mechanical Engineering, Vol. 46, 607-621. [9] Leveque, R.J. (1992) Numerical methods for conservation laws. Lectures in Mathematics, ETH Zuerich, Birkhauser Verlag, Basel. [10] Leskovar, M., J. Marn, B. Mavko (2000) Numerical analysis of multiphase mixing - comparison of first and second order accurate schemes. Fluid Mechanics Research, Vol. 27, 1-32. [II] Sethian, J.A. (1998) Level set methods. Cambridge University Press, Cambridge. Naslov avtorjev: dr. Matjaž Leskovar profdr. Borut Mavko Institut “Jožef Stefan” Jamova 39 1000 Ljubljana matjaz.leskovar@ijs.si borut.mavko@ijs.si Authors’ Address: Dr. Matjaž Leskovar Prof.Dr. Borut Mavko “Jožef Stefan” Institute Jamova 39 1000 Ljubljana, Slovenia matjaz.leskovar@ijs.si borut.mavko@ijs.si Prejeto: Received: 6.8.2001 Sprejeto: Accepted: 20.9.2002 VH^tTPsDDIK stran 458 © Strojni{ki vestnik 48(2002)8,459-466 © Journal of Mechanical Engineering 48(2002)8,459-466 ISSN 0039-2480 ISSN 0039-2480 UDK 629.367:531.232 UDC 629.367:531.232 Predhodna objava (1.03) Preliminary paper (1.03) Vpliv ra~unskega polmera obra~anja goseni~nega vozila na potrebno mo~ motorja pri obra~anju The Impact of a Fixed Kinematic Turning Radius of a Tracked Vehicle on the Engine Power required in a Turn Vjekoslav Stojkovi} - Dinko Mikuli} V prispevku je analiziran vpliv velikosti računskega polmera obračanja na potrebno moč motorja pri obračanju in na obremenjenost drsnih elementov mehanizma obračanja goseničnega vozila, ki ima mehanizem obračanja z več izračunanimi polmeri obračanja. Definirani so parametri, ki opisujejo relativno spremembo potrebne moči motorja pri obračanju, relativno spremembo zavorne moči na drsnih elementih mehanizma obračanja in spremembo koeficienta koristnega delovanja mehanizma obračanja v odvisnosti od relativnega polmera obračanja. Podana so priporočila za izbiranje računskih polmerov obračanja pri projektiranju mehanizma obračanja goseničnega vozila. © 2002 Strojniški vestnik. Vse pravice pridržane. (Ključne besede: goseničarji, obračanje vozil, moči motorjev, mehanizmi obračanja) This paper analyzes the impact of a fixed kinematic turning radius on the engine power required in a turn and on the load of friction elements in the turning mechanism of a tracked vehicle equipped with turning mechanisms that have several fixed kinematic turning radii. Parameters describing the relative change of engine power in a turn, the relative change of braking power on the friction elements of the turning mechanism, and the change of efficiency coefficient of the turning mechanism depending on the relative turning radius are defined. Recommendations regarding the choice of fixed kinematic turning radii, relating to the design of the turning mechanism of a tracked vehicle, are given. © 2002 Journal of Mechanical Engineering. All rights reserved. (Keywords: tracked vehicles, turning radius, engine power, turning mechanism) 0 UVOD Obračanje goseničnega vozila se doseže s spremembo hitrosti navijanja ene v primerjavi z drugo gosenico ob hkratnem oblikovanju različnih vlečnih sil na gosenicah ([1] in [2]). Dotikalni del gosenice dobiva ob vzdolžnem pomikanju pri obračanju še dodatno bočno premikanje po tleh. Zaradi vzdolžnih pomikov gosenice se pojavljajo odpori tudi pri gibanju vozila naravnost. Bočni pomiki gosenic povzročajo dodatne odpore zaradi bočnega trenja med gosenicami in tlemi, kakor tudi zaradi gnetenja, rezanja in premikov tal pod gosenicami. Zaradi tega se pojavi pri vstopu v obračanje goseničnega vozila porast skupnih odporov gibanja, zaradi česar se poveča obremenitev pogonskega motorja in pogonskega mehanizma, posledično pa tudi poveča obremenitev posameznih elementov v mehanizmih obračanja. Obremenitev motorja in pogonskega mehanizma goseničnega vozila ter posameznih elementov v mehanizmih za obračanje je v veliki meri 0 INTRODUCTION Turning a tracked vehicle is accomplished by changing the winding speed of one of its tracks with respect to the other, resulting in the simultaneous occurrance of different tractive forces on each track ([1] and [2]). The leaning part of the track, apart from the longitudinal, receives an additional lateral shift during the turn. Longitudinal shifts of the tracks induce the same kind of resistances as during rectilinear motion of the vehicle. Lateral shifts induce additional resistances due to lateral friction between the tracks and the ground and due to the compression, cutting and mixing of soil under the tracks. When a turn begins, the total resistance to motion of a tracked vehicle is increased, this causes an increased load on the engine and transmission, and therefore an increased load on the elements of the turning mechanisms. The loads on the engine and transmission of a tracked vehicle, as well as on the elements of its turning mechanisms, significantly depend on the gfin^OtJJIMISCSD 02-8 stran 459 |^BSSITIMIGC Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius odvisna od velikosti t.i. računskega polmera obračanja R . Računski polmer obračanja je tisti polmer obračanja, ki se realizira ob fiksnem prenosnem razmerju pogonske verige do notranje gosenice in brez drsenja drsnih elementov v mehanizmih obračanja ([1] in [2]). V tem prispevku je analiziran vpliv velikosti računskega polmera obračanja na potrebno moč motorja v obračanju in na obremenjenost drsnih elementov mehanizma obračanja na konkretnem primeru goseničnega vozila, ki ima mehanizme obračanja z več računskimi polmeri obračanja. Definirani so parametri, ki opisujejo relativno spremembo potrebne moči motorja pri obračanju, relativno spremembo zavorne sile na drsnih elementih mehanizma za obračanje in spremembo koeficienta koristnega delovanja mehanizma obračanja v odvisnosti od relativnega polmera obračanja. Na podlagi izvedene analize so dana priporočila za izbiranje računskega polmera obračanja. 1 DEFINIRANJE PARAMETROV ZA ANALIZIRANJE OBRAČANJA Analizirano je obračanje goseničnega vozila na vodoravni podlagi (sl. 1 in 2), ob naslednjih predpostavkah in omejitvah: - zanemarjeno je podrsavanje zunanje in notranje gosenice, - predpostavljena širina sledi gosenice je ena (B = 1), - zanemarjen je vpliv sredobežne sile, - predpostavljena teža vozila je ena (G = 1), - analizirano je obračanje s polmerom obračanja R v območju od obračanja okoli notranje gosenice do obračanja s prostim polmerom obračanja. Prosti polmer obračanja je tisti, pri katerem je sila na notranji gosenici enaka nič (F1 = 0). Pri obračanjih ki so večja od prostega polmera obračanja, na notranji gosenici nastane vlečna sila, pri polmerih obračanja, ki so manjši od prostega polmera obračanja, pa se na notranji gosenici formira zavorna sila ([1] in [2]). Na sliki 1 so prikazane sile in vrtilni momenti, ki delujejo na gosenično vozilo: R2 = odpor pri gibanju naravnost na zunanji gosenici, R1 = odpor pri gibanju naravnost na notranji gosenici F2 = vlečna sila na zunanji gosenici, F1 = zavorna sila na notranji gosenici, M = moment bočnih odporov obračanja. Odpora pri gibanju naravnost R1 in R ter moment bočnega odpora obračanja M, se določajo z izrazi ([1] in [2]): magnitude of the so-called fixed kinematic turning radius Rp. The fixed kinematic turning radius is the turning radius realized with a fixed transmission ratio of a kinematic chain to an inner track and without any sliding of the friction elements in the turning mechanism ([1] and [2]). This paper analyzes the impact of the fixed kinematic turning radius on the engine power required in a turn and on the load of the friction elements of the turning mechanism by using the concrete example of a tracked vehicle equipped with turning mechanisms that have several fixed kinematic turning radii. The parameters that describe the relative change of the required engine power in a turn, the relative change of the braking power on the friction elements of the turning mechanism, and the change of the efficiency coefficient of the turning mechanism depending on the relative turning radius are defined. On the basis of the performed analysis, recommendations regarding the choice of fixed kinematic turning radii are given. 1 DEFINITION OF PARAMETERS FOR ANALYZING A TURN The turn of a tracked vehicle on a horizontal surface (Figs. 1 and 2) is analyzed with the following assumptions and constraints: - sliding of the outer track and the inner track is neglected, - the distance between the tracks is assumed to be one (B = 1), - the influence of centrifugal force is neglected, - the vehicle’s weight is assumed to be one (G = 1), - turns with turning radii R in the interval ranging from a turn around the inner track to a turn with a free turning radius are analyzed. The free turning radius is characterized by the force on the inner track being zero (F1 = 0). For turns with radii larger than the free turning radius a tractive force is induced on the inner track, while for turns with radii less than the free turning radius a braking force is induced on the inner track ([1] and [2]). The forces and torques acting on a tracked vehicle are presented in Figure 1: R2 = resistance to rectilinear motion on the outer track, R1 = resistance to rectilinear motion on the inner track, F2 = tractive force on the outer track, F1 = braking force on the inner track, Mc = turning resistance torque. Resistances to rectilinear motion R1 and R2, and the turning resistance torque Mc are determined by the following expressions ([1] and [2]): R1 = 0,5 f G R2 = 0,5 f G Mc = mGL 4 (1), (2), (3), VBgfFMK stran 460 Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius F2 r> F1 L R2 C Mc r Y R1 Sl.1. Sile in momenti, ki delujejo pri obračanju goseničnega vozila Fig. 1. Forces and torques on a tracked vehicle in a turn M = m maks 0,925 + 0,15r (4), kjer so: f = koeficient odpora pri gibanju naravnost na določeni podlagi, p = relativni polmer obračanja (p = R/B), p = koeficient odpora obračanja na določeni podlagi in za določeni relativni polmer obračanja, H k = koeficient odpora obračanja na določeni podlagi pri/p= 0,5, L = dolžina dotikalnega dela gosenice. Vlečna sila na zunanji gosenici F2 in zavorna sila na notranji gosenici F1 lahko določimo z izrazoma ([1] in [2]): F2=R2 F1 =-R1 Na sliki 2 so prikazane hitrosti vozila pri obračanju in relativni polmeri obračanja goseničnega vozila: v2 = hitrost goseničnega vozila na zunanji gosenici, v1 = hitrost goseničnega vozila na notranji gosenici, where: f = the rectilinear motion resistance coefficient for a particular surface, r = the relative turning radius (r = R/B), m = the turning resistance coefficient for a particular surface and a particular relative turning radius, mmax = the turning resistance coefficient for a particular surface at r = 0.5, L = the length of the leaning part of a track. The tractive force on the outer track F2 and the braking force on the inner track F1 can be determined by the following expressions ([1] and [2]): (5), (6). Mc B Mc + B Figure 2 presents the velocities and relative turning radii of a turning tracked vehicle: v2 = the velocity of a tracked vehicle on the outer track, v1 = the velocity of a tracked vehicle on the inner track, vR Sl.2. Načrt hitrosti goseničnega vozila pri obračanju Fig. 2. Velocity plan of a turning tracked vehicle I IgfinHŽšlbJlIMlIgiCšD I stran 461 glTMDDC Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius v = hitrost težišča goseničnega vozila, v c = hitrost točke vozila, ki ohranja enako hitrost pri obračanju in pri gibanju naravnost, qM = kinematski parameter mehanizma obračanja (relativna koordinata točke vozila, ki ima hitrost v0). Uvedimo parameter qR, ki zadovoljuje naslednji pogoj [3]: vc = the velocity of the center of mass of a tracked vehicle, v0 = the velocity of a point on the vehicle which retains the same velocity in a turn as in rectilinear motion, qM = the kinematic parameter of the turning mechanism (relative coordinate of a point on the vehicle with velocity v0). Let us introduce parameter qR, satisfying the following condition [3]: .. (R1 + R2) qR B = Mc (7). Z uporabo izraza (7) uvajamo povezanost med momentom odpora obračanju M in momentom vsote odporov pri gibanju naravnost (R1 + R2)B. Po uvrstitvah izrazov (1), (2), in (3) v izraz (7) dobimo: Expression (7) describes the correlation between the turning resistance torque Mc and the torque of the sum of resistances to rectilinear motion . (R1 + R2) B. Inserting (1), (2) and (3) into (7) results in the following expression: mL qR = 4 fB (8). Uvedemo pojem relativnega računskega polmera obračanja rp: r Pri obračanju goseničnega vozila, razen odporov pri gibanju naravnost(R1 + R2), obstajajo tudi dodatni bočni odpori, ki oblikujejo moment odpora obračanja M. Potrebna moč za obvladovanje skupnih zunanjih odporov obračanja (P0) je večja od potrebne moči za premagovanje odporov pri gibanju naravnost (Pp) ([3] in [4]): The relative fixed kinematic turning radius rp is defined as: Rp = B (9). Besides resistances to rectilinear motion (R1 + R2), there are additional lateral resistances, which form the turning resistance torque Mc in the turning movement of a tracked vehicle. The power required for overcoming the total external resistances in a turn (P0) is larger than the power required for overcoming the resistance in rectilinear motion (Ppr) ([3] and [4]): P = (R + R ) v 1 2 0 P0 = (R1 + R2)v0 qR +r qM +r P =P Potrebna moč motorja za izvedbo obračanja goseničnega vozila (P ) se določi z izrazom ([3] in [4]): (10), (11), (12). qM +r The engine power required for accomplishing the turn of a tracked vehicle (Pmz) is determined by the following expressions ([3] and [4]): qR +r Pmz = (R1 + R2 )v0 qR +rp P =P mz pr qM +rp qR +rp Pri obračanju goseničnega vozila s polmeri obračanja, ki so različni od računskih, se na drsnih elementih mehanizma za obračanje sprošča moč drsenja (Pk), ki se določa z izrazom ([3] in [4]): Pk=(R1+R2)v0 (13), (14). qM +rp The power of sliding (Pk) that is spent on the friction elements of the turning mechanism during the turns of a tracked vehicle at turning radii different from the fixed kinematic turning radius is determined by the following expression ([3] and [4]): qR -qM r -rp qM qR -qM rpqM r-rp r (15), (16). qm+rpqm+r Uvedimo koeficient relativne potrebne moči The coefficient of relative engine power motorja pri obračanju (ymz), koeficient relativne moči required in a turn (ymz), the coefficient of relative VH^tTPsDDIK stran 462 Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius drsenja v drsnih elementih mehanizma za obračanje yk in koeficient koristnega delovanja mehanizma obračanja hm , in sicer ([3] in [4]): power of sliding in the friction elements of the turning mechanism yk, and the efficiency coefficient of the turning mechanism hmz are defined as ([3] and [4]): ym y P pr qR +rp mz qM +rp P yk = P pr qR -qM r - rp qM +rp qM P +r h mz = P mz qR +r qM +rp yk qm+r qr+r Na podlagi gornjih izrazov lahko povzamemo, da se koeficient relativne potrebne moči motorja pri obračanju ym , koeficient relativne moči podrsavanja v drsnih elementih mehanizma obračanja yk in koeficient koristnega delovanja mehanizma obračanja hm spreminjajo v odvisnosti od: -" koeficienta odpora gibanja f na tleh, kjer se obrača, - relativnega polmera obračanja r, - relativnega proračunskega polmera obračanja p in - parametra gibanja qM . Idealen mehanizem obračanja bi bil tisti, pri katerem bi za vsak relativni polmer obračanja dosegli y =1, yk = 0 in hm = 1. Vrednosti koeficientov ym , yk in hm za realni mehanizem obračanja pričajo o stopnjf uspešnosti projektnega oblikovanja mehanizma obračanja z vidika smotrne rabe moči motorja, a posredno tudi o njegovem vplivu na porabo pogonskega goriva. 2 ANALIZA VPLIVA VELIKOSTI RAČUNSKEGA POLMERA OBRAČANJA Za izvajanje analize je izbran mehanizem obračanja na goseničnem vozilu BVP - M80, katerega shema gibanja [5] je prikazana na sliki 3. Prikazan mehanizem obračanja sodi v skupino t.i. pogonskih prenosov v bloku (TUB), pri katerih je pogonsko in konstrukcijsko združena funkcija menjanja stopnje prenosa v menjalniku in menjanje hitrosti obračanja pogonskih koles pri obračanju goseničnega vozila. Ta pogonski prenos v bloku je sestavljen iz menjalnika (MJ), zbirnih diferencialov (SD2 in SD1), pomožnih drsnih spojk (fn2 in), pomožnih drsnih zavor (T in T 1) in drsnih zavor fn1 za zaustavljanje (T02 in T01). S sprožitvijo drsne zavore T0 v TUB do notranje gosenice nastane najmanjši relativni računski polmer obračanja rp0 = 0,5. S popolnim proženjem pomožne drsne spojnice fn v TUB do notranje gosenice nastane še po en relativni računski polmer obračanja v vsaki stopnji prenosa (rp = 1,2; rp = 3,1; rp3 = 4,8; rp = 7,5; p5 = 11,1). Obračanje s preostalimi polmeri obračanja (17), (18), (19), (20), (21), (22). These expressions show that the coefficient of relative engine power required in a turn ymz, the coefficient of relative power of sliding in the friction elements of the turning mechanism yk, and the efficiency coefficient of the turning mechanism hmz depend on: - the rectilinear motion resistance coefficient f for a particular surface, - the relative turning radius r, - the relative fixed kinematic turning radius rp, - the kinematic parameter qM. An ideal turning mechanism would achieve ymz = 1, yk = 0 and hmz = 1 for every turning radius. For real turning mechanisms the values of the coefficients ymz, yk and hmz indicate the quality of design, regarding rational use of engine power, and indirectly influence fuel consumption. 2 AN IMPACT ANALYSIS FOR A FIXED KINEMATIC TURNING RADIUS The analysis is conducted on the turning mechanism of the BVP-M80 tracked vehicle. Its kinematic scheme [5] is presented in Figure 3. This turning mechanism belongs to the category of the so-called block transmissions (BT). In block transmissions the functions of changing gears in a gearbox and of changing the rotation speed of the propulsion wheels during a turn are kinematically and constructionally unified. The presented block transmission consists of a gearbox (MJ), summing differentials (SD2 and SD1), auxiliary friction clutches (fn2 and fn1), auxiliary friction brakes (Tn2 and Tn1), and halting friction brakes (T02 and T01). By activating a halting friction brake T0 in the BT to the inner track, the minimum relative fixed kinematic turning radius of rp0 = 0.5 is realized. By fully activating an auxiliary friction clutch fn in the BT to the inner track, yet another relative fixed kinematic turning radius is realized for each gear (rp1 = 1.2; rp2 = 3.1; rp3 = 4.8; rp4 = 7.5; rp5 = 11.1). Turns Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius SD2 — T n2 T n1 _ SD1 Sl. 3. Shema gibanja mehanizma obračanja goseničnega vozila BVP M-80 Fig. 3. Kinematic scheme of the turning mechanism of the BVP-M80 tracked vehicle nastane z drsenjem enega od drsnih elementov v TUB (^ ali T ali T0). n Za gosenično vozilo BVP M-80 (5) so znane vrednosti [5] qM = 0,5 in L/B = 1,3. Analiziramo obračanje z vozilom na vodoravni s travo pokriti podlagi z osvojenima koeficientoma ([1] in [2]) f = 0,06 in// = 0,8. Grafični prikaz rezultatov računanja koeficientov ym , yk in ij , za izbrano vozilo je podan na slikah 4, 5 in 6. Pri analizi dobljenih rezultatov je opazno naslednje: - večanje relativnega računskega polmera obračanja vpliva na zmanjševanje koeficientov relativne potrebne moči motorja pri obračanju ym in koeficienta relativne zavorne moči yLob povečanju koeficienta koristnega delovanja mehanizma obračanja t, za relativne polmere with other turning radii are realized by sliding one of the friction elements in the BT (fn or Tn or T0). For the BVP M-80 tracked vehicle, the following values are known [5]: qM = 0.5 and L/B = 1.3. The turn of the vehicle on a horizontal sodded-grass surface is analyzed with the assumed coefficients ([1] and [2]) f = 0.06 and mmax = 0.8. Graphs of the coefficients ymz, yk and hmz are calculated for the chosen vehicle and presented in Figures 4, 5 and 6. Analysis of the results shows that: - with the increase of the relative fixed kinematic turning radius, the coefficient of relative engine power required in a turn ymz decreases, as does the coefficient of the relative power of sliding in the friction elements of the turning mechanism yk, while the efficiency coefficient of the turning mechanism hmz increases for relative turning radii Sl. 4. Koeficient relativne potrebne moči motorja pri obračanju Fig. 4. Coefficient of relative engine power required in a turn Sl. 5. Koeficient relativne moči drsenja v mehanizmu obračanja Fig. 5. Coefficient of relative power of sliding in the turning mechanism VH^tTPsDDIK stran 464 Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius 1,0 h mz 0,9 0,8 0,7 0,6 0,5 0,4 0,3 iw . ---*^ ___--- s^-rp' „ - ! \pp2 # >^ ¦ * * \ \Pp1 * \Pp0 10 20 30 40 50 Sl. 6. Koeficient koristnega dela mehanizma obračanja Fig. 6. Efficiency coefficient of the turning mechanism obračanja A ki so večji od relativnega računskega polmera obračanja za posamezno stopnjo prenosa, - zmanjševanje koeficientov ym in yk ter povečanje koeficienta t, je posebno izraženo v območju relativnega računskega polmera p i e {1,0; 5,0}, - za intervale računskih polmerov/ e {5,1; 15,0} je gibanje ugodnih vrednosti koeficientov ym , yk inij majhne intenzivnosti, - obstoj mz več relativnih računskih polmerov obračanja, ki se medsebojno razlikujejo po velikosti, omogoča prehod obračanja goseničnih vozil z višje ravni (p ) na sosednjo nižjo raven (p i-1) v primeru, ko je treba izvesti obračanje z relativnim polmerom, ki je manjši od p in večji od P 0 = 0,5, - prehod obračanja goseničnega vozila z višje ravni (p ) na sosednjo nižjo raven (pi-1) v primeru, ko je treba izvesti obračanje z relativnim polmerom, manjšim od (p ), a večjim od p = 0,5, zmanjšuje obremenitev pi pogonskega motorja in drsnih elementov mehanizma obračanja. 3 SKLEP Pri izvajanju manevra obračanja goseničnega vozila se z zmanjševanjem polmera obračanja pojavljajo povečani odpori obračanja in povečane obremenitve pogonskega motorja in sklopov v prenosnem mehanizmu za gibanje vozila. Obstoj relativnih računskih polmerov obračanja, ki so večji od p = 0,5, prispeva k zmanjševanju obremenitev pogonskega motorja in elementov v prenosih v primeru obračanja s polmeri obračanja, ki so enaki ali večji od relativnega računskega polmera obračanja. Koeficienti relativne potrebne moči motorja pri obračanju (ym ), relativne zavorne moči (yk) ter koeficient koristnega delovanja mehanizma obračanja (ij ) imajo ugodne vrednosti za to območje obračanja. r that are larger than the relative fixed kinematic turning radius rpi for the particular gear, the decrease of ymz and yk and the increase of hmz are particularly pronounced in the interval of the relative fixed kinematic turning radii rpi 1.0; 5.0}, - in the interval of relative fixed kinematic turning radii> e {5.1; 15.0} the favorable trend of values of the i coefficients ym , yk and ij is more moderate, - the existence of several relative fixed kinematic turning radii that are different in magnitude allows transitioning from a higher (p ) to the nearest lower level (p 1), for the case when a turn with relative radius less than p and larger than p = 0.5 is required, - transitioning from a higher (p ) to the nearest lower level (p 1), for the case when a turn with a relative radius less than p and larger than p 0 = 0.5 is required, decreases the engine load and the load on the friction elements of the turning mechanism. 3 CONCLUSION The decrease in turning radius during the turn of a tracked vehicle leads to increased turning resistances, an increased engine load and an increased load on the transmission devices of the vehicle. The existence of relative fixed kinematic turning radii larger than p = 0.5 enables a decrease in the engine load and the p0 load on the transmission elements for the cases of turns with turning radii greater than or equal to the relative fixed kinematic turning radius. The coefficient of relative engine power required in a turn (ym ), the coefficient of relative braking power (yk), and the efficiency coefficient of the turning mechanism (r, ) have favorable values for those turning radii. mz - Stojkovi} V. - Mikuli} D.: Vpliv ra~unskega polmera - The Impact of a Kinematic Turning Radius Ugodno gibanje vrednosti koeficientov ym , yk in rj je posebej izraženo pri relativnih računskih polmerih obračanja v območju p e {1,0; 5,0}. Za intervale relativnih računskih polmerov p i e {5,1; 15,0} je gibanje ugodnih vrednosti koeficientov ym , yk in rj umirjene intenzivnosti. V področju obračanj mz v katerem bi se uporabili relativni računski polmeri obračanja, ki so večji odp = 15, se koeficienti ym , yk inij le malo spreminjajo. i " Ob projektiranju novih pogonskih prenosov za gosenična vozila je zato priporočljivo uporabiti en računski polmer obračanja p 0 = 0,5 in več relativnih računskih polmerov obračanja v območju p e { 1,0; 15,0}. A favorable trend of values of the coefficients ym , yk and rj is particularly pronounced for relative fixed kinematic turning radii in the interval p e {1.0; 5.0}. In the interval of relative fixed kinematic turning radiip e { 5.1; 15.0} the favorable trend of values of ym , yk and rj is more moderate. In the range of turns with relative fixed kinematic turning radii larger than p = 15, the coefficients ym , yk and rj do not change i significantly. When designing the transmission of a tracked vehicle it is desirable to realize one fixed kinematic turning radius p = 0.5 and several other fixed kinematic turning radii in the interval p e { 1.0; 15.0}. 4 LITERATURA 4 REFERENCES [1] Zabavnikov, N. A. (1975) Osnovy teorii transportnyh gusenicnyh mašin, Masinostroenie, Moskva. [2] Farobin, J. E .(1970) Teorija povorota transportnyh mašin, Masinostroenie, Leningrad. [3] Nosov, N. A. (1972) Rasčet i konstruirovanie gusenicnyh mašin, Masinostroenie, Leningrad. [4] Krasnenkov V. I., A.D. Vašec (1986) Proektirovanie planetarnih mehanizmov transportnyh mašin, Masinostroenie, Moskva. [5] Borbeno vozilo pešadije BVP M-80A, TU-I, SSNO, Beograd, 1989. Naslova avtorjev: dr. Vjekoslav Stojkovic Ministrstvo za obrambo Inštitut obrambnih študij, raziskav in razvoja Bijenička cesta 46 10000 Zagreb, Hrvaška vjekoslav.stojkovic@morh.hr Dr. Dinko Mikulič Ministrstvo za obrambo Uprava za opremljanje in nabavo Trg Petra Kresimira IV. br. 1 10000 Zagreb, Hrvaška dmikulic@net.hr Author’s Address:Dr. Vjekoslav Stojkovič. Ministry of Defence Institute for Defence Studies, Researches & Development Bijenička cesta 46 HR-10000 Zagreb, Croatia vjekoslav.stojkovic@morh.hr Dr. Dinko Mikulič Ministry of Defence Dept. for Acquisition & Procurement Trg Petra Kresimira IV. br. 1 HR-10000 Zagreb, Croatia dmikulic@net.hr Prejeto: Received: 7.1.2002 Sprejeto: Accepted: 20.9.2002 VH^tTPsDDIK stran 466 © Strojni{ki vestnik 48(2002)8,467 ISSN 0039-2480 Osebne vesti © Journal of Mechanical Engineering 48(2002)8,467 ISSN 0039-2480 Personal Events Osebne vesti Personal Events Diplome DIPLOMIRALI SO Na Fakulteti za strojništvo Univerze v Mariboru so pridobili naziv univerzitetni diplomirani inženir strojništva: 29. avgusta 2002: Dušan DJUKIČ, Jasmin KALJUN, Banko KLEPAC, Matjaž KOROŠEC, Darinka POTOČNIK, Zorko TERPIN, Viljem URBANČIČ. * Na Fakulteti za strojništvo Univerze v Mariboru so pridobili naziv diplomirani inženir strojništva: 29. avgusta 2002: Peter COKAN, Srečko MEDVEŠEK Jože TREIBER Darko VRANEŠEVIČ. * Na Fakulteti za strojništvo Univerze v Mariboru so pridobili naziv inženir strojništva: 29. avgusta 2002: Anton BEOVIČ, Andrejka HOZJAN, Franc KALUŽA, Jože VAJDL, Denis VRTOVEC. Strojni{ki vestnik - Journal of Mechanical Engineering 2. KONFERENCA V DUBROVNIKU TRAJNOSTNI RAZVOJ ENERGIJSKIH, VODNIH IN OKOLJSKIH SISTEMOV 15.-20. junij 2003, Dubrovnik, Hrvaška 2nd DUBROVNIK CONFERENCE SUSTAINABLE DEVELOPMENT OF ENERGY, WATER AND ENVIRONMENT SYSTEMS June 15-20 2003, Dubrovnik, Croatia Organizatorja Univerza v Zagrebu, Zagreb, Hrvaška Instituto Superior Tecnico, Lizbona, Portugalska Cilji Spodbujanje novega področja trajnostne znanosti, s katero poskušamo razumeti osnovne lastnosti medsebojnega delovanja med naravo in družbo; Obravnava trajnostnega pojmovanja energije, vode in okolja ter njihove povezave z razvojem v celoti; Razčlenitev možnih znanstvenih in tehnoloških postopkov, ki povzročajo spreminjanje energije, vode in okolja; Predstavitev modelov energijskih, vodnih in okoljskih sistemov ter njihovo vrednotenje; Predstavitev ocenitev energijskih, vodnih in okoljskih sistemov z večimi merili ter z upoštevanjem gospodarskih, družbenih, okoljskih vidikov ter vidikov rabe virov. Naslov Naslov: 2003 Dubrovnik Conference, FSB, Ivana Lučiča 5, HR-10000 Zagreb, Hrvaška Faks: +385 1 6156940; E-pošta: dubrovnik2003@fsb.hr; www.dubrovnik2003.fsb.hr Organisers University of Zagreb, Zagreb, Croatia Instituto Superior Tecnico, Lisbon, Portugal Objectives . To promote a new field of sustainability science that seeks to understand the fundamental character of interactions between nature and society; . To discuss sustainability concept of energy, water and environment and its relation to the global development; . To analyse potential scientific and technological processes reflecting energy, water and environment exchange; . To present energy, water and environment systems models and their evaluation; . To present multi criteria assessment of energy, water and environment systems taking into a consideration economic, social, environmental and resource use aspects. Contact Address: 2003 Dubrovnik Conference, FSB, Ivana Lučiča 5, HR-10000 Zagreb, Croatia Fax: +385 1 6156940; E-mail: dubrovnik2003@fsb.hr; www.dubrovnik2003.fsb.hr VH^tTPsDDIK stran 468 . . . . . © Strojni{ki vestnik 48(2002)8,469-470 ISSN 0039-2480 Navodila avtorjem © Journal of Mechanical Engineering 48(2002)8,469-470 ISSN 0039-2480 Instructions for Authors Navodila avtorjem Instructions for Authors Članki morajo vsebovati: - naslov, povzetek, besedilo članka in podnaslove slik v slovenskem in angleškem jeziku, - dvojezične preglednice in slike (diagrami, risbe ali fotografije), - seznam literature in - podatke o avtorjih. Strojniški vestnik izhaja od leta 1992 v dveh jezikih, tj. v slovenščini in angleščini, zato je obvezen prevod v angleščino. Obe besedili morata biti strokovno in jezikovno med seboj usklajeni. Članki naj bodo kratki in naj obsegajo približno 8 tipkanih strani. Izjemoma so strokovni članki, na željo avtorja, lahko tudi samo v slovenščini, vsebovati pa morajo angleški povzetek. Vsebina članka Članek naj bo napisan v naslednji obliki: - Naslov, ki primerno opisuje vsebino članka. - Povzetek, ki naj bo skrajšana oblika članka in naj ne presega 250 besed. Povzetek mora vsebovati osnove, jedro in cilje raziskave, uporabljeno metodologijo dela,povzetek rezulatov in osnovne sklepe. - Uvod, v katerem naj bo pregled novejšega stanja in zadostne informacije za razumevanje ter pregled rezultatov dela, predstavljenih v članku. - Teorija. - Eksperimentalni del, ki naj vsebuje podatke o postavitvi preskusa in metode, uporabljene pri pridobitvi rezultatov. - Rezultati, ki naj bodo jasno prikazani, po potrebi v obliki slik in preglednic. - Razprava, v kateri naj bodo prikazane povezave in posplošitve, uporabljene za pridobitev rezultatov. Prikazana naj bo tudi pomembnost rezultatov in primerjava s poprej objavljenimi deli. (Zaradi narave posameznih raziskav so lahko rezultati in razprava, za jasnost in preprostejše bralčevo razumevanje, združeni v eno poglavje.) - Sklepi, v katerih naj bo prikazan en ali več sklepov, ki izhajajo iz rezultatov in razprave. - Literatura, ki mora biti v besedilu oštevilčena zaporedno in označena z oglatimi oklepaji [1] ter na koncu članka zbrana v seznamu literature. Vse opombe naj bodo označene z uporabo dvignjene številke1. Oblika članka Besedilo naj bo pisano na listih formata A4, z dvojnim presledkom med vrstami in s 3 cm širokim robom, da je dovolj prostora za popravke lektorjev. Najbolje je, da pripravite besedilo v urejevalnilku Microsoft Word. Hkrati dostavite odtis članka na papirju, vključno z vsemi slikami in preglednicami ter identično kopijo v elektronski obliki. Prosimo, da ne uporabljate urejevalnika LaTeX, saj program, s katerim pripravljamo Strojniški vestnik, ne uporablja njegovega formata. V urejevalniku LaTeX oblikujte grafe, preglednice in enačbe in jih stiskajte na kakovostnem laserskem tiskalniku, da jih bomo lahko presneli. Enačbe naj bodo v besedilu postavljene v ločene vrstice in na desnem robu označene s tekočo številko v okroglih oklepajih Enote in okrajšave V besedilu, preglednicah in slikah uporabljajte le standardne označbe in okrajšave SI. Simbole fizikalnih veličin v besedilu pišite poševno (kurzivno), (npr. v, T, n itn.). Simbole enot, ki sestojijo iz črk, pa pokončno (npr. ms1, K, min, mm itn.). Vse okrajšave naj bodo, ko se prvič pojavijo, napisane v celoti v slovenskem jeziku, npr. časovno spremenljiva geometrija (ČSG). Papers submitted for publication should comprise: - Title, Abstract, Main Body of Text and Figure Captions in Slovene and English, - Bilingual Tables and Figures (graphs, drawings or photographs), - List of references and - Information about the authors. Since 1992, the Journal of Mechanical Engineering has been published bilingually, in Slovenian and English. The two texts must be compatible both in terms of technical content and language. Papers should be as short as possible and should on average comprise 8 typed pages. In exceptional cases, at the request of the authors, speciality papers may be written only in Slovene, but must include an English abstract. The format of the paper The paper should be written in the following format: - A Title, which adequately describes the content of the paper. - An Abstract, which should be viewed as a miniversion of the paper and should not exceed 250 words. The Abstract should state the principal objectives and the scope of the investigation, the methodology employed, summarize the results and state the principal conclusions. - An Introduction, which should provide a review of recent literature and sufficient background information to allow the results of the paper to be understood and evaluated. - A Theory - An Experimental section, which should provide details of the experimental set-up and the methods used for obtaining the results. - A Results section, which should clearly and concisely present the data using figures and tables where appropriate. - A Discussion section, which should describe the relationships and generalisations shown by the results and discuss the significance of the results making comparisons with previously published work. (Because of the nature of some studies it may be appropriate to combine the Results and Discussion sections into a single section to improve the clarity and make it easier for the reader.) - Conclusions, which should present one or more conclusions that have been drawn from the results and subsequent discussion. - References, which must be numbered consecutively in the text using square brackets [1] and collected together in a reference list at the end of the paper. Any footnotes should be indicated by the use of a superscript1. The layout of the text Texts should be written in A4 format, with double spacing and margins of 3 cm to provide editors with space to write in their corrections. Microsoft Word for Windows is the preferred format for submission. One hard copy, including all figures, tables and illustrations and an identical electronic version of the manuscript must be submitted simultaneously. Please do not use a LaTeX text editor, since this is not compatible with the publishing procedure of the Journal of Mechanical Engineering. Graphs, tables and equations in LaTeX may be supplied in good quality hard-copy format, so that they can be copied for inclusion in the Journal. Equations should be on a separate line in the main body of the text and marked on the right-hand side of the page with numbers in round brackets. Units and abbreviations Only standard SI symbols and abbreviations should be used in the text, tables and figures. Symbols for physical quantities in the text should be written in Italics (e.g. v, T, n , etc.). Symbols for units that consist of letters should be in plain text (e.g. ms-1, K, min, mm, etc.). All abbreviations should be spelt out in full on first appearance, e.g., variable time geometry (VTG). stran 469 glTMDDC Strojni{ki vestnik - Journal of Mechanical Engineering Slike Slike morajo biti zaporedno oštevilčene in označene, v besedilu in podnaslovu, kot sl. 1, sl. 2 itn. Posnete naj bodo v kateremkoli od razširjenih formatov, npr. BMP, JPG, GIF. Za pripravo diagramov in risb priporočamo CDR format (CorelDraw), saj so slike v njem vektorske in jih lahko pri končni obdelavi preprosto povečujemo ali pomanjšujemo. Pri označevanju osi v diagramih, kadar je le mogoče, uporabite označbe veličin (npr. t, v, m itn.), da ni potrebno dvojezično označevanje. V diagramih z več krivuljami, mora biti vsaka krivulja označena. Pomen oznake mora biti pojasnjen v podnapisu slike. Vse označbe na slikah morajo biti dvojezične. Za vse slike po fotografskih posnetkih je treba priložiti izvirne fotografije ali kakovostno narejen posnetek. V izjemnih primerih so lahko slike tudi barvne. Preglednice Preglednice morajo biti zaporedno oštevilčene in označene, v besedilu in podnaslovu, kot preglednica 1, preglednica 2 itn. V preglednicah ne uporabljajte izpisanih imen veličin, ampak samo ustrezne simbole, da se izognemo dvojezični podvojitvi imen. K fizikalnim veličinam, npr. t (pisano poševno), pripišite enote (pisano pokončno) v novo vrsto brez oklepajev. Vsi podnaslovi preglednic morajo biti dvojezični. Seznam literature Vsa literatura mora biti navedena v seznamu na koncu članka v prikazani obliki po vrsti za revije, zbornike in knjige: [1] Tarng, Y.S., Y.S. Wang (1994) A new adaptive controler for constant turning force. Int J Adv Manuf Technol 9(1994) London, pp. 211-216. [2] Čuš, F., J. Balič (1996) Rationale Gestaltung der organisatorischen Ablaufe im Werkzeugwesen. Proceedings of International Conference on Computer Integration Manufacturing Zakopane, 14.-17. maj 1996. [3] Oertli, PC. (1977) Praktische Wirtschaftskybernetik. Carl Hanser Verlag Minchen. Podatki o avtorjih Članku priložite tudi podatke o avtorjih: imena, nazive, popolne poštne naslove, številke telefona in faksa ter naslove elektronske pošte. Sprejem člankov in avtorske pravice Uredništvo Strojniškega vestnika si pridržuje pravico do odločanja o sprejemu članka za objavo, strokovno oceno recenzentov in morebitnem predlogu za krajšanje ali izpopolnitev ter terminološke in jezikovne korekture. Avtor mora predložiti pisno izjavo, da je besedilo njegovo izvirno delo in ni bilo v dani obliki še nikjer objavljeno. Z objavo preidejo avtorske pravice na Strojniški vestnik. Pri morebitnih kasnejših objavah mora biti SV naveden kot vir. Rokopisi člankov ostanejo v arhivu SV Vsa nadaljnja pojasnila daje: Uredništvo STROJNIŠKEGA VESTNIKA p.p. 197/IV 1001 Ljubljana Telefon: (01) 4771-757 Telefaks: (01) 2518-567 E-mail: strojniski.vestnik@fs.uni-lj.si Figures Figures must be cited in consecutive numerical order in the text and referred to in both the text and the caption as Fig. 1, Fig. 2, etc. Figures may be saved in any common format, e.g. BMP, GIF, JPG. However, the use of CDR format (CorelDraw) is recommended for graphs and line drawings, since vector images can be easily reduced or enlarged during final processing of the paper. When labelling axes, physical quantities, e.g. t, v, m, etc. should be used whenever possible to minimise the need to label the axes in two languages. Multi-curve graphs should have individual curves marked with a symbol, the meaning of the symbol should be explained in the figure caption. All figure captions must be bilingual. Good quality black-and-white photographs or scanned images should be supplied for illustrations. In certain circumstances, colour figures may be considered. Tables Tables must be cited in consecutive numerical order in the text and referred to in both the text and the caption as Table 1, Table 2, etc. The use of names for quantities in tables should be avoided if possible: corresponding symbols are preferred to minimise the need to use both Slovenian and English names. In addition to the physical quantity, e.g. t (in Italics), units (normal text), should be added in new line without brackets. All table captions must be bilingual. The list of references References should be collected at the end of the paper in the following styles for journals, proceedings and books, respectively: [1] Tarng, Y.S., Y.S. Wang (1994) A new adaptive controler for constant turning force. Int J Adv Manuf Technol 9(1994) London, pp. 211-216. [2] Čuš, F., J. Balič (1996) Rationale Gestaltung der organisatorischen Ablaufe im Werkzeugwesen. Proceedings of International Conference on Computer Integration Manufacturing Zakopane, 14.-17. maj 1996. [3] Oertli, PC. (1977) Praktische Wirtschaftskybernetik. Carl Hanser Verlag Minchen. Author information The following information about the authors should be enclosed with the paper: names, complete postal addresses, telephone and fax numbers and E-mail addresses. Acceptance of papers and copyright The Editorial Committee of the Journal of Mechanical Engineering reserves the right to decide whether a paper is acceptable for publication, obtain professional reviews for submitted papers, and if necessary, require changes to the content, length or language. Authors must also enclose a written statement that the paper is original unpublished work, and not under consideration for publication elsewhere. On publication, copyright for the paper shall pass to the Journal of Mechanical Engineering. The JME must be stated as a source in all later publications. Papers will be kept in the archives of the JME. You can obtain further information from: Editorial Board of the JOURNAL OF MECHANICAL ENGINEERING P.O.Box 197/IV 1001 Ljubljana, Slovenia Telephone: +386 (0)1 4771-757 Fax: +386 (0)1 2518-567 E-mail: strojniski.vestnik@fs.uni-lj.si 02-8 VH^tTPsDDIK stran 470