Unsteady simulation of tonal noise from isolated centrifugal fan

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