Numerical Estimation of End Corrections in Extended-Duct and Perforated-Duct Mufflers

Abstract

One-dimensional models for extended-duct and perforated-duct mufflers require the introduction of end corrections in order to account for multidimensional effects at the junctions. In this paper, a numerical two-dimensional finite element calculation has been used in order to obtain information on these end corrections. The results have been validated through comparison with experimental measurements performed with a modified version of the impulse method. Then, the influence of the different geometric characteristics of the mufflers on the end correction have been studied. A general correlation in terms of relevant nondimensional parameters is given for extended-duct mufflers, whereas for perforated mufflers a general correlation has not been obtained due to the eventual coupling with other attenuation mechanisms.