Measurement and Analysis of Fan Noise

초록

This paper reviews the development of the technology for understanding and prediction of noise sources from axial and centrifugal blowers. Emphasis is placed on sound power measurement, acoustic scaling, identification method of noise source, and noise prediction scheme. A mathematical model based on dimensional analysis for an axial fan encountering non-uniform inlet turbulence is applied to identify noise source characteristics for a low-frequent gust problem. The flow structures in a small propeller fan are also studied to explain the correlation between an unsteady rotating stall and noise source characteristics. The estimation scheme of wide-band sound power levels produced by a centrifugal blower is presented and discussed with the measured data. The status of fan noise prediction is also presented with recent advances in Computational Aero-acoustics(CAA).