FEA Approach for Calculating Back Pressure in Automotive Muffler

This paper deals with the application of Finite Element Analysis in accelerating the development of an automotive muffler. The essential function of a muffler is to route the exhaust gases from the engine exhaust manifold while reducing the noise and back-pressure. Noise reduction is an emerging concern in the automotive industry, and reduction in back-pressure enhances the fuel economy of the engine.

Virtual simulation for back-pressure testing is performed by Computational Fluid Dynamic (CFD) analysis using AcuSolve CFD. Finite Element (FE) model generation of the muffler structure is performed using HyperMesh as the preprocessor. The structural mesh is modeled using 2D shell elements, wherein the internal tubes with fine perforated holes are considered. The CFD fluid meshing is done with tetra elements using AcuConsole as the CFD preprocessor. The back pressure generated across the muffler is determined by measuring and in putting the mass flow rate of the exhaust gases entering the muffler inlet pipe. HyperView is used for post processing the CFD results and reviewing the airflow streamlines. The exhaust gas velocity and pressure plots are studied across the internal tubes and perforated holes, and the back pressure is measured. The CFD results are correlated with physical test results.