Modification Of Muffler For Minidor Three-Wheeler

Abstract

Internal combustion engines generate acoustic pulse due to combustion process. In order to minimize the acoustic pulse IC engine use muffler in the exhaust system. The higher sound pressure wave generated in the engine combustion chamber then passes through the exhaust manifold and attenuated inside the muffler to certain level. Thus the exhaust gas with reduced sound pressure gets released to the surrounding passing through the exhaust pipe. Some muffler designs are not much effective in their sound attenuation to desired sound pressure level due to less effective design nature of the muffler and contradicting behavior of sound reduction with back pressure. Inefficient muffler not only causes sound pollution but also vibration to vehicle components and increases toxic exhaust gas emission to the environment. In this research work specific vehicle was considered which releases higher sound pressure. Higher sound pressure generated during combustion propagates through the exhaust pipe, but with the help of effective muffler it is possible to reduce it to a desired level. For the effectiveness of the research work data was gathered from passengers and drivers to know what they feel and suggest about the sound emission of this vehicle. The goal of this research was to improve the acoustic performance of Minidor, Force three-wheeler vehicle by modifying the performance of existing muffler to minimize sound pollution. Muffler modification was done based on transmission loss prediction, prototype manufacturing and testing experimentally. A part modeling was done by using Auto CAD tool. Earlier method of muffler design was by trial and error method by manufacturing mufflers with various arrangement of internal pipes, perforations size, inlet and exit pipes and testing until desired output is gained. Here design was analyzed not by the earlier method, rather using COMSOL Multiphysics simulation prediction of muffler performance was done before manufacturing the component. From the result of the simulation, it was shown that the modified model has increased transmission loss by an average of 3.2 dB with little increase in backpressure. Finally, prototype of the modified Reactive muffler for Minidor, Force three-wheeler with reduced sound level and acceptable back pressure was manufactured. The sound pressure level at the exit of the existing and manufactured muffler was measured experimentally and the modified muffler gives about 2 dB sound reduction at idling and 3.7dB at full throttle position.