Most of the noise prediction methods, which has already been used, only applicable at low frequency range, below the first transverse duct mode. A developed method at this work, which suggested by Schram, avoided many simplification assumptions and 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 a large-eddy simulation (LES) and 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.