Estimating Transmission Loss of Muffler having Two Inlets and Two Outlets

Abstract

Predicting the acoustics behavior of the exhaust muffler before a prototype model built can save the both substantial amount of time and resources. There are various simulation tools available now a day which can predict the acoustics performance of the muffler. In order to use these tools effectively, it is very important to understand what is the most effective tool for the intended purpose of analysis. as well as how the various elements in the exhaust muffler affects the muffler performance.This thesis presents how transmission loss for various muffler configuration can be determined through analytical and FEA methods. As extant literature is primarily dedicated to single inlet single outlet exhaust muffler, this work includes acoustics analysis of simple expansion chamber with two inlets one outlet, two inlets two outlets on each end face. Which gave us the advantage of decreasing backpressure. There are both analytical and FEA method used for each muffler configuration for determining transmission loss and the results are compared against each other. The analytical method used is impedance matrix method in which a global impedance matrix is derived in order to get transmission loss. The second and third methods used are the FEA using COMSOL Multiphysics and ANSYS15.0 which also gives the satisfactory result for all the configuration in order to understand which FEA tool is very well suited for predicting the transmission loss results are compared against each other and with analytical method. This thesis also includes the parametric analysis of single inlet single outlet in order to understood the effects of various elements on the muffler performance