Analysis On Properties Of A New Structure Split-stream-rushing Muffler Unit

The exhaust noise is the main noise source in internal combustion engine, and to use exhaust muffler is the most efficient way for reducing the exhaust noise. In design of the silencer the two main performances:acoustic performance and aerodynamic performance, must be taken into account, and normally they are contradictory. Therefore, to seek a better way in reducing the noise without lowering its aerodynamic performance has been the focus on muffler research at home and abroad.Based on our group’s early research on the split-stream rushing muffler, in this thesis a new structure of this type of muffler unit was presented, its acoustic and aerodynamic performances were simulated by using 3D simulation software.For the aerodynamic performance of the new muffler unit, the airflow pressure loss as well as the internal airflow characteristics were studied by using the simulation of computational fluid dynamics (CFD) and the test, the test verified that the principle of the new muffler unit is correct. On the basis of the fluid mechanics method, the structure of the new muffler unit was optimized, the resulted muffler unit’s pressure loss was numerically simulated, and the result shows that the pressure loss has been greatly improved.From the acoustic performance of the new muffler unit, the transmission loss was simulated and analyzed by using the acoustic simulation software; the results show that it has a good performance in noise reduction in the frequency range of 20Hz-3000Hz.