Study On The Influence Of Structural Parameters Of Automobile Exhaust Muffler On Muffler Performance

Engine exhaust noise is one of the main sources of vehicle noise. The most direct and effective method of controlling exhaust noise is that muffler is installed in the exhaust system. Design better attenuation performance, low power consumption has become an important subject in the muffler exhaust noise control.In this paper, taking the exhaust muffler of HT1000-2 for the object of study, first of all, acoustic finite element analysis of the key structure parameters of muffler is made by using simulation software Virtual.Lab Acoustics. Study the effect of the expansion ratio, the length of expansion chamber, the number of perforation on the baffle in expansion chambers, perforation radius and pipe perforation rate on acoustic performance of muffler, which provides a theoretical basis for optimization design of muffler. Then, using two regression orthogonal combination design test, discusses the important effect of the degree of various structural parameters on the acoustic performance of muffler, and an appropriate regression equation was gave to provide convenience for the optimization design of the muffler. At the same time, the successful application of this method is the good guidance for the future research and development of the muffler. Finally, according to the regression equation, using simulation software of MATLAB, get the extreme value of the regression equation, and the finite element model is established for the simulation. The error between the results of numerical calculation and simulation is only 1.29%, which shows that the established regression equation is very accurate and can be used for the optimization design of muffler, and once again proves that the three dimensional finite element acoustic simulation has high reliability.Research results show that:expansion ratio of the multi-cavity muffler not only determines the amount of noise, also affect the attenuation peak frequency and sound frequency. With increasing of the expansion ratio, the failure frequency of high frequency moved toward the low frequency. Expansion chamber length has little effect on noise reduction. With increasing of the length of expansion chamber, frequency of noise elimination shift to low frequency. In a certain range, increasing the length of the third chamber is advantageous to improve the silencing effect in high frequency. Influence of hole number and hole radius on the reduction of the separator between each chamber of the muffler is very significant, the number of holes and hole radius is smaller, the greater the magnitude, the wider attenuation band. Increasing the perforation rate on crossing flow perforated tube can improve the silencing effect in high frequency. In the same perforation rate, Influence of perforation radius on the noise reduction effect is greater than the number of perforation. Compared with the simple cavity muffler, there are some differences in the influence of acoustic performance of various structural parameters of multi-cavity muffler. There are remarkable regression relationship between the key structural parameters and the sum of transmission loss of muffler. Influence of structure parameters on the transmission loss is different, and the rankings of their influence on the transmission loss are as follows: diaphragm perforation radius, the number of the partition perforation, the interaction of diaphragm perforation radius, the number of square diaphragm perforation, the square of the number and the radius of the diaphragm perforation, the square of the length of the third cavity.