Performance Prediction And Acoustic Characteristics Of Automobile Exhaust Muffler

Exhaust noise is one of the primary parts of automobile noise sources, which is reduced by the most effective component automobile exhaust system. The exhaust system plays an important role in noise control of automobile and city life.In this paper, based on the transmission matrix method, the transmission matrixes of several basic anechoic units are deduced and the mathematic models are built to calculate the insert loss of the muffler. The structure parameters are optimized based on the punishment function method. The software of performance prediction and optimization for muffle design is developed by using Visual Basic.The flow field and acoustic field in the muffler are investigated numerically by using the finite element method; the velocity, temperature and pressure distribution in the muffler are calculated by using the ANSYS CFX software and the sound field in muffler is analyzed by SYSNOISE software so the influences made by velocity, temperature and pressure in muffler are analyzed. Also the influences made by temperature and the liner effect are considered. Based on all of the analysis, the structures of muffler are improved and the performance of the improved muffler display that the effect of noise elimination in most frequency bands has visibly improvement. Through calculating the flow field in the improved muffler the aerodynamic performance also has some improvement.