RESEARCH ON SOUND TRANSMISSION CHARACTERISTICS OF SINGLE-SECTION EXPANDED ANTI-NOISE MUFFLER
The automobile muffler can reduce the transmission of internal noise in the pipeline system,and has an excellent effect on reducing the exhaust noise of automotive engines.The three-dimensional model of a single section expansion resistant muffler was estab-lished by using COMSOL software.The grid independence was verified to eliminate the influence of grid parameters on the transmission loss of the muffler.The principle of Control variates was used to assign parameters to the inlet and outlet position offset,length ratio,and expansion ratio,and different sound pressure and transmission loss nephograms were obtained.Research has shown that the noise reduction ability is consistent when the position deviation of the inlet and outlet pipes is found at frequencies ranging from 0~1800 Hz.However,when the frequency is between 1000~3000 Hz,the greater the position deviation of the inlet and outlet pipes of the muffler,the better its noise reduction ability;When the frequency is between 0~3500 Hz,as the length of the expansion chamber decreases,the transmission loss curve of the muffler moves towards the higher frequency direction,while the peak value of the transmission loss does not change significantly.