Study on the acoustic performance of perforated duct muffler

In engine exhaust systems, perforated element is usually used to improve the acoustic attenuation performance of mufflers. To predict the acoustic attenuation performance of perforated duct mufflers under working conditions, three-dimensional finite element method considering the effect of gas flow was developed. In the numerical computations, perforation acoustic impedance model was applied to consider the acoustic influencer of perforated element with gas flow. To verify the accuracy of predictions, a test bench was build up to measure the transmission loss of perforated duct mufflers with gas flow. The predictions and measurement showed that the effect of porosity and Mach number of gas flow is obvious on the transmission loss of perforated duct mufflers.