Unsteady simulation of tonal noise from isolated centrifugal fan

Abstract

In this study, an isolated centrifugal fan is investigated for the aerodynamic and acoustic performances using RANS and URANS simulations. The noise is predicted by coupling the URANS and the Ffowcs Williams and Hawkings acoustic analogy. The aerodynamic properties obtained from RANS and URANS are consistent with the experimental data. The magnitudes of the tonal noise at the blade passing frequencies are well predicted. Recirculating flows, which are responsible for reducing the fan efficiency and increasing the noise generation, are observed between the shroud and the blade trailing edges. It is found that the recirculating flows are associated with the gap between the shroud and the inlet duct.