Computer Simulation Of Acoustic Performance Of Motorcycle Muffler

The research object of this paper is the muffler, which is a key function in automotive noise control. In order to obtain goals in the two aspects of energy and environment, this paper studies the most common used expansion chamber muffler in the two fields of fluid dynamic and acoustics. So that a design that results in high noise attenuation value and low backpressure structure can be obtained.Using fluid dynamics FEM and three dimensional acoustic FEM in meticulous analysis of expansion muffler structure, this paper studies the influences of each muffler components' position, dimension, form and quantity on the fluid dynamic and acoustic performances; therefore the paper indicates that the end of the intruding tube is the linchpin of the fluid dynamic performance of the whole muffler structure, the springhead of muffler fluid dynamic performance is the smoothness of air current,the main factor which affects the acoustic attenuation value of expansion chamber muffler is the grade of saltation of the section of air conducting access, and the attenuation value of specific frequency can be dramatically enhanced by carefully designing the length of expansion chamber.Based on the intergration of the result so f acoustic and fluid dynamic analysis, this paper points out that synthetical acoustic and fluid dynamic performance of muffler can be obtained by using square expansion chamber,by stringing together several podgy expansion chambers,by applying noise absorbing material on chamber walls,by making chambers and pipers co-axial,by adding fillets on the end of intruding pipes,and by making the diameter of outlet pipe a little greater than the diameter of the inlet pipe.Finally, based on the results of expansion chamber muffler noise attenuation testing, the validity of the finite element analyzing in this paper is verified, and the further studies in the future is envisaged.