Diffuser perforation effects on the performance of a vent silencer

Numerical simulations are carried out for 3D steady compressible turbulent flowof air inside a vent silencer to investigate the effect of the diffuser perforation on the flow structure and acoustic performance of the silencer. The governing equations for the turbulent flow are solved using the finite volume method. The broadband noise source model is used in the simulations to predict the acoustic power level in the silencer. The inlet total absolute pressure ranges from 250 to 1000 kPa and the outlet absolute pressure is set to atmospheric. The results are presented in terms of the transmission loss of the silencer. The parameters considered in the present study are the diffuser holes diameters and the length of the perforated pipe in addition to the inflow conditions. In all the simulation cases, the inlet sound power level was in the range of the practical measurements of 120 to 150 dB. The results are presented to show the flow structure and the acoustic performance. The results show that increasing either the diffuser hole diameters or the length of the perforated pipe, the transmission loss of the silencer increases.