35 KB1473 KB28 KB199920252011Čudina, MirkoPrezelj, Jurijletnik:57številka:6str. 468-476ISSN:0039-2480COBISSID:11839771URN:URN:NBN:SI:doc-BTUECVEUenAssociation of Mechanical Engineers and Technicians of Slovenia et al.Zveza strojnih inženirjev in tehnikov Slovenije et al.Strojniški vestnikactive noise controlaktivno dušenje hrupaengfanhrupprezračevalni kanalisecondary sourcesekundarni zračni virventilation ductventilatorjiA secondary source configuration for control of a ventilation fan noise in ducts|The main noise source in heating, ventilation, and air conditioning systems is usually a ventilating fan. Noise, generated by the ventilating fan is transmitted through the duct into the living and working environment. A typical fan noise spectrum consists of a broadband noise, which is superimposed with pure tones. Different methods are available to reduce a transmission of such noise from the ventilating fan into the living and working environment. In this article it is demonstrated how a feedforward active noise control system can be implemented together with a side branch resonator. Effectiveness of the feedforward active noise control system depends on the quality of a reference signal, which should be in a perfect correlation with the primary noise. An acoustic feedback is the main problem of feedforward active noise control systems in ducts. A combined method uses asingle loudspeaker to work as a dipole source and a side branch resonator to reduce the acoustic feedback. A side branch resonator reduces noise transmission in a narrowband frequency range as well. In this article, a theoretical background of a dipole source with a side branch resonator is presented, along with some measurement results and simulations of active noise controlAktivno dušenje hrupa (ADH) deluje na principu dodajanja protihrupa v primarni hrup. Protihrup ima v časovnem prostoru popolnoma enako pojavno obliko kot primarni hrup, le da ima drugačen predznak. Protihrup ustvarimo s sekundarnim virom, ki je največkrat kar dinamični zvočnik. Signal za protihrup dobimo iz referenčnega signala z algoritmi za ADH. Referenčni signal mora biti v popolni korelaciji s primarnim hrupom. Na delovanje sistema za ADHmočno vpliva ravno kakovost referenčnega signala. Za aktivno dušenje širokopasovnega in naključnega hrupa, ki je največkrat posledica naključnega turbulentnega gibanja zraka, smo danes še vedno primorani uporabljati mikrofone. Referenčni mikrofon za zaznavanje referenčnega signala se najpogosteje postavi v bližino primarnega vira hrupa. Referenčni mikrofon, ki naj bi zaznal samo primarni hrup, zazna tudi protihrup iz sekundarnega vira, skaterimsmo izničili primarni hrup v predhodnem korakuTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo