Numerical analysis of acoustic attenuation and flow resistance characteristics of double expansion chamber silencers

The complex sound field and flow field inside silencer require the use of three-dimensional numerical methods to predict its acoustic and aerodynamic performance. In the present study, the finite element method (FEM) is used to predict the acoustic attenuation performance, and the finite volume method (FVM) is employed to calculate the flow resistance of double expansion chamber silencers. The effects of internal structures and inlet orientation on the acoustic attenuation and flow resistance characteristics of the silencers are investigated in detail. The methods for reducing the flow resistance of the double expansion chamber silencers are explored, and then their influences on the acoustic attenuation characteristics of the silencers are examined. The numerical results demonstrated that the use of flow guiding annuluses at the entrances and exits of tubes or perforated tube between two neighboring coaxial tubes may reduce the pressure drop through the silencers significantly and affect the acoustic attenuation performance of silencers marginally in general.