Improved Numerical Noise Predictions for Axial Fans

The market needs for quieter engine cooling modules and the upcoming stringent noise level regulations have led Valeo to develop a series of numerical codes which will give the fan designer accurate noise predictions and will also ideally complement its CFD simulation based design for its future fan technology [1].

The current approach involves three levels of noise prediction: first a global sound pressure level estimate which will use the fluid 2D CFD blade cascade information; secondly, a spectral distribution which relies on fan loads to provide a first estimate of the subjective noise; finally, a temporal approach based on the Ffowcs-Williams theory which will come the closest to the actual measurements and will fully use the 3D CFD fan data.

Validation calculations and first predictions have shown that, even if an accurate absolute noise level cannot always be obtained (within 1 dBA), observed experimental trends are already well captured.