Flow Field Analysis and Improvement of Automobile Exhaust System Cold End

The 3D computational domain model of a certain automobile exhaust system cold end was built by software UG, shaped grid by Gambit, numerical simulated by computational fluid dynamics software FLUENT. Analysis of the system's internal flow quality , indicated that the system's back pressure fulfilled the design requirements, the pre-muffler's internal flow field is smooth, but the main muffler's wall temperature differences are high, and there are large turbulent flow and jet flow in it, therefore the main muffler's wall has a higher risk of hot deformation, the main muffler has a greater potential for regenerative noise and one of its inner bafflers is more likely to be damaged because of shock. For these reasons, the main muffler's structure should be improved. After modified, the main muffler's temperature distribution is more even, turbulence energy grows down, and the baffler opposite the jet flow is thickened.