Morteza Bayati - PhD student, Amirkabir University of Technology, Tehran, Iran
Mehran Tadjfar - Associate Professor, Amirkabir University of Technology, Tehran, Iran

Most of the noise prediction methods, which have been previously used, only applicable at low frequencies range, below the first transverse duct mode. A developed method at this work, which was suggested by Schram, avoided many simplifying assumptions and it is quite powerful for high Helmholtz numbers, i.e. when the turbulence/body interaction region is acoustically non-compact. By using numerical methods and an appropriate Green function, the method is applied to the prediction of sound in a duct obstructed by a diaphragm. The source fluctuations of the flow field are computed by large-eddy simulation (LES) and they are fed to the following acoustical computation as input data.The predicted power spectrum shows a fairly good agreement with a direct noise computation (DNC) results.

Aeroacoustic, Diaphragm, Helmholtz number