Structure Improvement And Acoustic Characteristics Analysis Of Automobile Muffler

Exhaust noise is one of the primary parts of automobile noise sources,which is with good results to reduce automobile engine exhaust noise when use exhaust muffler.At present,acoustic performance and fluid dynamic performance are considered as the two key factors in the evaluation of mufflers.The former performance shows the ability of reducing noises while the latter performance indicates the level of fluid dynamic,both have the same important position.In this thesis,a comprehensive Analysis of the muffler’s acoustic and fluid dynamic performance was conducted with finite element method.First,make a transmission loss performance analysis on the different structure parameters of the simple muffler,focuses on the cross-flow muffler structure which change from the perforated pipe,analyze the acoustic performance,while discussing the impact of structural parameters on the fuild dynamic performance,the study found that the cross-flow perforated pipe have better acoustic performance at low frequency and high frequency,among them,Perforated plate aperture affect the fuild dynamic properties seriously,and cause a sharp increase in exhaust backpressure.Then,make an experimental analysis on a vehicle exhaust muffler.By acoustic analysis unit which lms.virtual.lab software provided and make analysis on the former muffler,also have an analysis on the fluid dynamics performance with CFD software,by use the temperature field in CFD to verify the influence of temperature on the muffler performance.According to the above and make structural improvements in former muffler,after that we calculate acoustic performance and fuild dynamic of them,results show that the acoustic performance of improved one has been greatly improved,while,fuild dynamic performance also have some improvement.