1371 KB41 KB201320252013Bombek, GorazdFike, MatejHribernik, AlešHriberšek, Matjažletnik:6številka:iss. 1str. 33-50COBISSID:1024132956ISSN:1855-5748URN:URN:NBN:SI:doc-KWGOJXJVenFakulteta za energetikoJET on-lineJournal of energy technologyelektrična merjenjaelektrodinamikaizguba energijelow Reynolds number applicationprenos električne energijeS809 airfoilunsteady static-stallvetrne turbineThe unsteady static-stall aerodynamic characteristics of an S809 airfoil at low Reynolds numbers| Aerodinamične karakteristike nestacionarnega zastoja na profilu S809 pri nizkih Reynoldsovih številih|An investigation was conducted to study the unsteady static-stall characteristics of an S809 airfoil whose aerodynamic characteristics are representative of a horizontal axis wind-turbine. It is very difficult to experimentally investigate this phenomenon, especially when attempting to study the development of flow-separation when the blades are rotating. The application of wind-tunnel tests or CFD simulation is obviously more appropriate. In order to investigate unsteady static-stall regarding the aerodynamic characteristics of an S809 airfoil, a comparative study was performed to obtain numerical and experimental results for the flow-separation position, airfoil pressure distribution, and velocity profiling that included velocity oscillations. The experimental results were acquired using PIV (Particle Image Velocimetry) and the study was performed atvarious angles of attack (AOA). No separation was observed at low AOA, but at 9.6° AOA the separation vortex comprised 50% of the airfoil's chord length,whilst a complete stalling of the airfoil occurred at 20° AOA. The observed separation zone was not steady but was found to oscillate around its mean-position at an interval of +- 10% of the chord's length. Neither of the applied turbulence models k-eta nor SST used in 2D unsteady simulation predicted this oscillation, although the numerical results agreed fairly well with those experimentally obtained, especially the averaged velocity and vorticity fields around the suction side of the airfoil when using the SST modelOpravljena je bila raziskava, kjer smo preučevali karakteristike nestacionanega statičnega zastoja na profilu S809, katerega aerodinamične karakteristike so reprezentativne za vetrne turbine z horizontalno osjo. Eksperimentalno je zelo težko preučevati ta pojav, še posebej kadar želimo preučevati odcepljanje toka na rotirajočih lopaticah. Izvedba meritev v zračnem tunelu oziroma simulacij računalniške dinamike tekočin je primernejše. Z namenom raziskovanja nestacionarnega statičnega zastoja glede aerodinamičnih karakteristik S809 profila je bila opravljena primerjalna študija, tako so bili primerjani eksperimentalni in numerični rezultati položaja odcepitve toka, porazdelitve tlaka po profilu in hitrostih profilov vključno z oscilacijami hitrosti. Eksperimentalni rezultati so bili pridobljeni z uporabo PIV (meritev hitrosti z odslikavo delcev) in pri različnih napadnih kotih. Pri nizkih napadnih kotih nismo zaznali odcepitve toka, pri napadnem kotu 9.6° je odcepljen vrtinec zavzemal 50% dolžine tetive profila, pri napadnem kotu 20° zastojni vrtinec obsega ves profil. Opazovana področje odcepitve ni bilo stacionarno ampak smo ugotovili, da oscilira okrog njene srednje pozicije v intervalu +- 10% dolžine tetive. Uporabljena turbulentna modela, k-eta in SST, v 2D časovno odvisnih simulacijah nista napovedala teh oscilacij, čeprav so se numerični rezultati dokaj dobro ujemaliz eksperimentalno pridobljenimi, še posebej polja povprečne hitrosti in polja vrtinčnosti na sesalni strani profila pri uporabi SST turbulentnega modelaTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Mariboru, Fakulteta za energetiko