Author : Sandeep G Thorat, B S Kothavale, Swapnil S Hatwalane and Dhiraj Bhaskar

New regulations and standards for noise reductions and emission compel the automobile industries to make some improvements in the design of silencer for attaining desired noise reduction. In this project, modifications are desired in the silencer design of upcoming Eicher tractor to fulfill the current standards. The current noise level at Operator Ear Level (OEL) is 97dB (decibels), it is desired to reduce it to 94 dB and below. Also the maximum backpressure of 50 mm of Hg is to be maintained. New design should be analyzed with respect to both acoustics and back pressure. As per the various studies reactive mufflers with extended inlet and outlet pipes into muffler, which is not present in current design can significantly reduce the noise level. Helmholtz resonator can also be introduced to cancel the noise of dominating frequencies. Also a sound absorbing material like glass fibers and steel wool can be incorporated for better results. Further, the design modifications are to be verified for noise reduction by COMSOL Multi-physics software. Also the numerical results for transmission loss will be verified with experimentally measured results.

Keywords: Operator Ear Level (OEL), backpressure, mufflers, COMSOL Multiphysics, transmission loss