Reduction of Noise Emission from Minidor Three Wheeler with Effective Novel Muffler

Abstract

Internal combustion (IC) engines generate higher acoustic pulse due to combustion process. In order to minimize the acoustic pulse to certain level, IC engine use muffler in the exhaust system. Thus, the exhaust gas with reduced sound pressure gets released to the surrounding passing through the exhaust pipe. Inefficient muffler design causes sound pollution, vibration to vehicle components, increase in back pressure to the engine, and increases toxic exhaust gas emission to the environment. In this research work specific vehicle was considered which releases higher sound pressure. For the effectiveness of the 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 a given vehicle by modifying the geometry of existing muffler components. Muffler modification was done based on transmission loss prediction, prototype manufacturing, and testing experimentally. A part modelling was done by using Auto CAD tool. The design was analyzed and prediction of muffler performance was done using COMSOL Multiphysics simulation. 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 back pressure, which is acceptable. 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 3.7 dB at full throttle position.