Calculation Of Acoustic Characteristics Of Automobile Exhaust Muffler And Its Optimum Design

The exhaust system noise of automobile is the important component of automobile noise. In order to reduce automobile noise and abate noise pollution, the optimum design of muffler is of great importance to society and economy.In this paper,the developmental survey,research methods,types and characteristics of automobile exhaust muffler , are presented. The objective indexes of exhaust muffler noise should be paid more attention to,but also the subjective perception of people should be regarded.That is to say, other subjective indexes of exhaust noise should be analyzed and calculated in the analysis of noise.Considering the effects of mean flow and temperature gradient to the performance of muffler,the transmission matrices of some basic muffler elements are deduced , and calculation model is developed.This model can be used to calculate the acoustic and air dynamical performance.After the 3-D spectrum is established ,the influence of some parameters on the reduction of muffler noise of single expansion chamber is more visual.The acoustic characteristic of muffler is scaled by the insertion loss of the frequency band which is scaled by the insertion loss of octave or one-third octave.After calculating the insertion loss of each frequency band,the overall sound attenuation of muffler is calculated.Then the object function and optimum model is established and the optimum design of the structural parameters of muffler is carried out.On the premise of considering the reduction of muffler noise and pressure loss, the optimum design of some structural parameters of one type of muffler is accomplished.After the optimum design,the performance of the exhaust muffler is improved. So it is significant to apply it in the practice.