Analysis and Evaluation of the Acoustical Performance of an Internal Combustion Engine Exhaust Muffler

Nowadays, the noise pollution from the vehicle is getting serious especially the demand of the usage of vehicle is increasing in the city, the noise level at the urban also increase significantly during the day time. Hence the high level of noise from the vehicle is commonly reduce by the use of muffler which install in the exhaust system. The increasing need of noise control had resulted in the need of muffler with better acoustic properties. By using the baffle plate in exhaust muffler is known to improve the sound transmission loss. However, limited study had been conducted on the effect of baffle configuration on transmission loss and pressure difference in exhaust mufflers, particularly the number and the distribution of hole on the baffle plate. Hence, to develop a numerical model for investigating the car exhaust muffler with various type of parameter. By analyse the performance such as back pressure and transmission loss on car exhaust muffler with difference parameter as well as improve the existing design of exhaust muffler that can able to reduce the noise level with more efficient. The modification of the muffler in terms of various parameter can carry out in this project to reduce the noise level generated from the internal combustion engine. The modification of the muffler can conduct by using the numerical method to develop a 3D model by using SolidWorks and acoustic simulation of muffler by using ANSYS software. It was found that in the frequency range of 0 – 3000 Hz, the three number of hole with both plate of the orientation are same was 8 Pa of back pressure lower than the original muffler with negligible effect on flow performance of the muffler. The propose muffler with design 7 was 73 Pa of back pressure lower and 3 dB of transmission loss higher than original muffler. After the modification of muffler with different parameter of hole on baffle plate and the arrangement of perforated hole on the baffle plate, this project show how can it suppressed the noise level and back pressure from the exhaust muffler.