Abstract：Three-dimensional finite element method is developed to predict the acoustic attenuation perform-ance of perforated tube dissipative silencers. Comparisons of transmission loss predictions with experimental re-sults for straight through perforated tube silencers illustrated that the finite element method can predict the acous-tic attenuation characteristics of perforated tube silencers accurately. The finite element method is then used to investigate the effects of filling density (or flow-resistivity) and thickness of sound-absorbing material，and po-rosity of perforation on the acoustic attenuation performance of silencers. Increasing filling density of sound-absorbing material can improve the acoustic attenuation performance of dissipative silencers at higher frequencies, and shift the peak to lower frequency. Increasing the thickness of sound-absorbing material may improve the acoustic attenuation performance of dissipative silencers at higher frequencies, while the effect on lower fre-quency acoustic performance is marginal. The placement of sound-absorbing material in the expansion chamber can enhance the noise reduction at mid to high frequencies, and eliminate the pass-frequencies. Increasing poros-ity of perforation can significantly improve acoustic attenuation at relatively high frequencies, and shift the peak to higher frequencies. The backing cavity between the cylindrical shell and sound-absorbing material may lead to a flat acoustic attenuation curve in a relative wide frequency range.
2010, Vol. 29 
