A Study Of Muffler Performance With 3-D Finite Element Calculation Method

Automobile industry has been developing very fast. And at the same time, automobile noise pollution has been severer than before. The reduction of exhaust system noise is the key to the reduction of automobile noise. At present, the main method to reduce exhaust noise is by setting muffler in automobile exhaust system. So calculating and predicting the performance of the muffler is of great significance and the work of this thesis is a practice in this aspect.With the FE software ANSYS, the performance of reactive muffler is calculated by the 3-D FEM (Finite Element method) in this thesis. The mathematical model of inner acoustic FE equation is established and the calculation formulas about TL (transmission loss) and IL (insertion loss) of muffler are deduced. On this basis, with highly-precise acoustic elements FLUID30 and FLUID 130, the FE model of two kinds of mufflers are developed under static state working condition. By means of acoustic transmission matrix, the muffler is being simulated directly and indirectly. The foul-terminal network parameter, TL and IL are calculated, too. In the end, through comparing simulation results and experiment results, it shows that calculated values coincide well with measured values. The simulation method is proved to be correct and calculation of acoustic performance of muffler by ANSYS FE analysis software is also proved to be practical and expedient.Muffler theory, FEM theory, ANSYS application, double-propagation haphazard stimulation technology are included in this thesis. Some key factors such as FE mesh demarcation, establishment of FEM model and post-processor of ANSYS are also discussed in this thesis. So, important theory and project example of the performance of muffler prediction are provided by this thesis.