Enhancing Noise Attenuation in Exhaust Mufflers on Response to Baffle Configuration

Using baffles in exhaust mufflers is known to improve transmission loss and reduce the noise emitted to the environment. This paper postulates that baffle cut ratio affects the muffler performance in the same effect as a shell-and-tube heat exchanger, consequently the baffle cut ratio should affect the muffler performance. This study presents a parametric study on the effect of baffle configuration on predicted transmission loss and pressure drop. The effect of baffle cut ratio, baffle spacing, number of baffle holes, and hole pattern distribution on transmission loss was investigated. Results showed that reducing the baffle cut ratio increased the transmission loss at intermediate frequencies by up to 45% while decreasing the spacing between muffler plates improved the muffler transmission loss by 40%. The assessment of the baffle effect on flow using a thermal baffle approach model indicated a sudden drop in fluid temperature in axial flow direction by 15% as the baffle cut ratio changed from 75% to 25. To the best of authors knowledge, the effect of baffle cut ratio configuration on acoustic response and back pressure has not been previously reported or investigated.