Acoustic attenuation performance calculation and analysis of straight-through perforated tube silencers

AbstrcatA one_dimensional analytical approach and a three_dimensional substructure boundary element method (BEM) are developed to predict the acoustic attenuation performance of straight_through perforated tube silencers. Comparisons of transmission loss predictions with experimental results for single chamber straight_through perforated tube silencers illustrated that the three_dimensional approach is needed for accurate prediction at higher frequencies, while the one_dimensional analytical approach provides a reasonable accuracy at lower frequencies only. The BEM was then used to investigate the effects of porosity and geometrical parameters on the acoustic attenuation performance of straight_through perforated tube silencers. Increasing the porosity may expand the effective acoustic attenuation to higher frequency. The transmission loss of silencer with partially_perforated tube exhibits a superposition of dome attenuation and axial resonance in the plane wave region. By choosing the length and location of perforated section to match the resonances with the troughs of the silencer, a desirable broadband acoustic attenuation may be obtained. The double expansion chamber may greatly improve the noise attenuation performance of straight through perforated tube silencers in the middle frequency range.