Numerical Investigation on the Design and Development of Automotive Exhaust Muffler –A Case Study

Attaining better acoustic performance and back-pressure is a continuous research area in the design and development of passenger vehicle exhaust system. Design parameters such as tail pipe, resonator, internal pipes and baffles, muffler dimensions, number of flow reversals, perforated holes size and number etc. govern the muffler design. However, the analysis on the flow directivity from tail pipe is limited. A case study is demonstrated in this work on the development of automotive muffler with due consideration of back pressure and flow directivity from tail pipe. CFD methodology is engaged to evaluate the back pressure of different muffler configurations. The experimental and numerical results of backpressure have been validated. The numerical results are in close agreement with experimental results. It was observed that the influence on back pressure with reducing the quantity of baffle plate, Increasing the tail pipe diameter and twin tail pipe with bypassing flow through inner pipe are 2.7%, 1.4% and 34.4%, respectively. The impact of tail pipe angle on flow directivity is assessed based on the flow uniformity index. Effect of each operating parameter on the back pressure is evaluated with statistical approach.