Numerical prediction and optimization of the tonal noise radiated by an automotive alternator using a Lattice Boltzmann Method

In this paper, the flow-induced noise radiated by an automotive alternator at high rotational speed is studied. A 3 dimensional unsteady and compressible computational approach based on the Lattice-Boltzmann Method (LBM) is applied to predict simultaneously the transient turbulent flow and the corresponding acoustic field in a hemi-anechoic environment. In particular, the effect of locating holes on the radiated tonal noise is analysed. Experimental and numerical acoustic powers with and without locating holes are compared with good agreements. Transient and spectral analyses are performed to bring a better understanding of the flow features at the origin of the main tonal contribution.