Mutual validation of muffler performance evaluation methods using field measurements and finite element analysis

Abstract

The design of large industrial mufflers poses a problem to many companies involved in their fabrication. Most of the design and evaluation theory has been developed using one dimensional acoustics. However, it is well known that in large ducts, the one dimensional propagation assumption breaks down at much lower frequencies. The three dimensional propagation of acoustic waves in complex geometries is a very difficult problem to solve analytically. For this reason, numerical methods are employed. In this study, a finite element analysis (FEA) program is validated using field measurements. Three well known muffler performance criteria and three different large sized mufflers are considered. The three performance metrics are noise reduction (NR), insertion loss (IL), and transmission loss (TL). During the study, sufficient agreement for validation of the performance evaluation methods was found. A method for reconciling idealistic FEA simulations and in situ measurements by accounting for significantly high ambient noise is developed.