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.