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LES 및 음향상사 모델을 이용한 에어컨 실내기의 공력 소음원에 대한 수치해석적 연구
민윤홍(Yunhong Min),강성원(Seongwon Kang),허남건(Nahmgeon Hur),박정택(Jeongtaek Park) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In the present study, the aerodynamic noise source was analyzed for air-conditioner indoor unit. The 3-D LES was used because the noise prediction using acoustic analogy method requires the accurate flow result in a vicinity of noise source. For 3-D computation, the sound correction method which is derived by Kato was used to take account of longer span length. Since the quadrupole contribution is negligible in subsonic flow of air-conditioner indoor unit, the Farassat formulation 1A which considers only monopole and dipole source was applied to predict far-field acoustic pressure. In air-conditioner indoor unit, the three noise sources are blade and two fan casings. The predicted SPL (Sound Pressure Level) using the three noise sources was good agreement with the experimental data. When the separated vortex interacts with each noise source, the pressure fluctuation on the surfaces causes the main noise in subsonic flow. Especially the blade was dominant source because there were the most active form of interaction between blades and vortex. Also the blade had the effect of BPF (Blade Passing Frequency) peak noise as the specific flow structures in the cross-flow fan.