Research On The Local-structure Effects To The Performance Of Resistant Mufflers

It has been a prominent problem that the vehicle radiated noise affecting the quality of life and work, with the rapid increasing of industrial capacity. And it is no doubt that the engine exhaust noise, as the major component of the vehicle noise, is the key to noise control. Installing exhaust mufflers is a feasible, simple and effective measure, which has been used widely, to control the exhaust noise, and it have a great important influence on the dynamic characteristics of the engine. So, we must balance muffler’s acoustic attenuation performance with aerodynamic properties in the design process.The property of the exhaust muffler matched different machinery in urgent need of improvement, with the development of request in the field of noise environment. It is very difficult to improve acoustic attenuation performance by changing the muffler’s outer size, with the restraint of installation space and the structure of the engine exhaust pipe. In this case, we can only change the inner structure, meanwhile, some inner size is limited, such as internal pipe’s length and diameter, in order to ensure that the air flow fluency and avoid structure interference.The objective of this paper is to explore the method of the muffler matching design by adjusting the local structure, without changing the whole structure. For that, in this paper, several typical anechoic constructions be researched and analyzed so as to give the reasonable proposal for the muffler’s design.Firstly, on the basis of mastering the design theory and the research methods of the resistance muffler, some anechoic constructions with intubation structure and perforated tube were designed, moreover, and analyzed influence of the change of local structure parameters on the muffler’s acoustic attenuation performance, resistance characteristic and internal flow field distribution.After that, an improvement project was proposed for a certain type excavator muffler, on the basis of analyzing its noise characteristics and structural parameters. And then, the contrastive analysis on acoustic attenuation performance, resistance characteristic and internal flow field distribution by means of numerical simulation, indicate that the transmission loss obviously improved and the pressure loss unchanged basically. Finally, a measurement system based on PIV (particle image velocimetry) is set up, and observed the internal air motion of a typical sample resistant muffler, and the test result also shows that the control of smoke particles and air motion in current system need improved, to achieve the coordinated control of both and get uniform air flow with particles under different velocity.