Acoustic performance analysis of muffler by varying sound absorption materials

Abstract

Noise is an unwanted sound which is greatly affecting the human health over the years. The high pressure gases coming out from the exhaust system of automotive vehicle is one such unwanted noise, which is increasing drastically. This lead to increase in health issue and looking into it, various legislative bodies have set limitation on the overall sound level coming from the exhaust system. Muffler is one such device which is used for reducing this exhaust system noise. These mufflers are composed of different acoustic elements such as perforated tube, baffles, sound absorption materials etc. Hybrid muffler is one such muffler which is composed of baffles, uniform tube, and sound absorption materials which dissipates the high pressure gases. In this study, the acoustic performance of hybrid muffler is obtained by implementing different grades of sound absorption materials such as Glasswool, rockwool, melamine etc. Pressure acoustic frequency domain analysis was performed for these mufflers to determine the acoustic performance parameters i.e. transmission loss and sound pressure level using Comsol Multiphysics. The maximum transmission loss value was obtained for the muffler, when Glasswool 701 with flow resistivity of 14000 Pa.s/m2 was used as the sound absorption material. The results obtained through this analysis was validated through experiment performed in impedance tube setup This hybrid muffler helped in reducing maximum exhaust system noise and the overall sound pressure level also decreased at the outlet of the hybrid muffler.