Numerical noise prediction: application to radial fans

In this study, aerodynamics and aeroacoustics of two radial fans are investigated by using a hybrid computational aeroacoustics method. Unsteady turbulent flow field of both fans is simulated with large eddy simulation (LES). Acoustic sources are computed based on the pressure fluctuations. Inhomogeneous wave equation, which accounts for the propagation, diffraction and scattering of the acoustic sources inside the volute, is solved to determine the far field sound pressure level with the boundary element method. Numerically obtained sound pressure level distributions are in a good agreement with experimental data. Sound pressure level distribution in narrow band frequency spectrum, directivity of the acoustic waves and the overall sound power level are predicted numerically with a high accuracy. Furthermore, results of the LES provide an insight to the turbulent flow and noise generation mechanisms.

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