Study On Flow Noise Generation Of Multi-Chamber Exhaust Muffler

With the people’s living standard’s improving, there are higher requirements forvibration and noise of automobiles. As an effective tool to lower the exhaust noise level,the muffler is widely applied in exhaust system of automobiles. As the rotation speed ofengine becomes higher, flow regenerated noise develops into the main factor ofevaluating the performance of mufflers. The research on influence factors to flowregenerated noise, especially involved with structure, is much meaningful to highperformence muffler design.The experimental test is an effective and commonly used way to study flowregenerated noise of muffler. In this paper, a test platform for flow regenerated noise ofmuffler is built and dual-microphone test method has been applied to muffler’s flowregenerated noise measurement, then the relations between flow regenerated noise andflow velocity are analyzed.Based on the close relationship of flow regenerated noise and flow velocity, theFLUENT software is used to analyze the interior flow field of a set of mufflers and itsstructures’ effecs factors. Meanwhile, according to four sets of mufflers’ interior flowfield characteristics, the main structual factors affecting interior flow field are figuredout.In this paper, an allied simulating method of FLUENT and LMS.Virtual.Labsoftware is attempted, in which the wideband noise source model and CAA model areused. Also BP neural network is applied to study the methods of flow regenerated noisepredicting and the relative merits and scope of application are compared, whichprovides new concept and method to flow regenerated noise predicting.