Optimization of Backpressure in Exhaust Muffler for Automobile

Abstract

The goal of this study is to optimise the exhaust middle box muffler of an automobile by focusing on the design of the perforated pipes. Back pressure and pressure drop in the exhaust are two characteristics that contribute to the various effects of an internal combustion engine. In this study, the pressure distribution of an existing exhaust middle box muffler on the perforated pipe is evaluated using Computational Fluid Dynamic (CFD) software, and the suitable perforated pipe is identified to improve the middle box muffler performance. The simulation of fluid flow inside a passage of perforated pipe with the same diameter and length but different perforation diameters and distance between perforations was carried out in this study. The CFD analysis simulation results showed the flow pattern with  pressure contours for each sample. The results also revealed that each sample had a different pressure drop. An optimised design of perforations inside the middle box muffler pipe results in less pressure drop, which improves exhaust system performance. The simulation results are plotted and a comparison of various perforation diameter and distance can be seen. Larger distance between perforations at 20 mm gives large discrepancies in the results which is 15% difference of pressure drop as compared to smaller distance between perforations that gives less than 1% difference of pressure drop for 6mm and 7mm diameter of perforated pipes. The results also shows that 5mm of perforation diameter gives even larger pressure drop as high as 44.66%.