Acoustics : Fan noise spectrum

F.CHAMBONNET

Hi !

I'd like to evaluate the noise of fans and propellers.

I have run unsteady calculations to have nice aerodynamic fields (pressure, velocity...) then I turned on the FWH model and ran some more time steps.

I consider the zone 'blades' i.e. all the fan blades as my main noise source.

fft plotting shows discrete tone noises at the shaft frequency and harmonics and not the BPF and harmonics spectrum that I expected.

So far, I suspect that I would achieve a typical fan noise spectrum by having one zone per blade.

Has anyone ever experienced this and can confirm it ?

Thanks.

FC.