In this study, computational aeroacoustics methods are employed to analyze the flow and the noise emission in a centrifugal fan. Unsteady flow inside the centrifugal fan is predicted with large eddy simulation. Acoustic sources are computed based on the results of the time-dependent flow simulation. The turbulent pressure fluctuations on the blades and on the volute of the fan are used as the source terms in the acoustic analogy of Ffowcs Williams and Hawkings. Propagation, diffraction and scattering of the acoustic sources inside the volute are computed with the boundary element method. Numerically obtained sound pressure level distribution in narrow band frequency spectrum is compared with experimental measurements at certain microphone points. The numerical and experimental sound intensity maps are also compared to validate the numerical prediction of directivity. Computational results agree well with the experimental data and provide an insight of the noise emission mechanisms.

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