Numerical Analysis Research On Acoustic Performance And Aerodynamic Characteristic Of Automobile Exhaust System

The noise of engine plays a main role in NVH performance of automobiles, while exhausting noise contributes the most important part. At present, it's common to control the exhausting noise by setting up mufflers along the exhaust system. However, the mufflers result in producing backpressure which degrades the power and oil-consume effect of engine. So it's necessary to study the accoustic performance and aerodynamic performance of mufflers.The research on muffler in the early term based principally on one-dimention planar wave theory, then theoretically analyse muffler according to four-pole sound transmission matrix method and neural network method. But calculations of transmission loss and backpressure in traditional method will result to big tolerance and can't meet the practical requirements as the muffler is three-dimentional and quite complex in structure. As the development of numerical simulation technology, it will be effective to conduct finite element analysis of muffler by using professional software. This new method provides a new way to guide designing muffler.In this paper, we study firstly acoustic performance and aerodynamic performance of the basic unit of mufflers. Then the software, SYSNOISE and FLUENT, is applied to build a FEM model of the practical exhaust system of SRV engine and to simulate the acoustic performance and aerodynamic characteristic. According to the simulation, the backpressure and transmission loss are calculated that show the validity of the numerical analysis in comparison with experiment results. Also we evaluate the distribution of fluid velocity, tempreture, and sound pressure to put forward improvement measures. The method is a good guide and foundation to lead to optimization design of muffler.