Simplified techniques for predicting the transmission loss of a circular dissipative silencer

Abstract

A closed-form analytical solution for the transmission loss of a dissipative silencer with a circular cross-section is described. The silencer contains a bulk reacting acoustic absorbent which is separated from a mean gas flow by a perforated screen. Theoretical predictions of the silencer transmission loss for three different dissipative silencers are compared both with experimental data and with another more complex modelling technique. Good agreement is noted between the analytical theory and experimental data in the low-to-medium frequency range. Below a defined upper frequency limit the analytical technique is also shown to provide good agreement with the finite element method. In addition it is observed that, even for relatively high open area porosities, the perforate screen has a significant effect on dissipative silencer performance.