Transmission Loss Evaluation by Utilizing the Integrated Transfer Matrix Method in Conjunction with Wave 1D for Perforation Optimization on Plug Muffler by Using Absorptive Material

The noise that automobile exhaust systems produce is significantly reduced by the use of mufflers. Mufflers reduce noise while driving and improve the quality of the surrounding environment by utilizing a variety of design strategies. Mufflers use complex construction and materials to reduce sound by utilizing fluid dynamics and acoustics concepts. In this research work, first of all a reactive muffler has been made in which the inlet and outlet are connected by an extended pipe. Nevertheless, the considerable backpressure that plug mufflers naturally produce is a drawback that could negatively impact engine performance. This chapter presents a novel structural modification to the plug muffler in order to improve its acoustic performance by the improvement on transmission loss. One-dimensional gas dynamic simulation tool is utilized to predict exhaust orifice noise during the initial phases of engine development. This encompasses forecasting how well each part of the exhaust line will perform acoustically. A widely used component of exhaust systems enhances acoustic damping by using the plug flow muffler. This research examines that how the acoustic performance of plug mufflers on a concentric tube can be predicted based on varying porosity on the pipe. Finally, a different absorptive material is introduced in the optimized simulation model, and an absorptive material which gives higher sound transmission loss is adopted. This analysis has focused on four configurations with different perforation rate and two configurations with absorptive material like rock wool and S glass with 60 kg/m3 packing density. Initially, compare the optimum result with simple expansion chamber muffler. For each of the four configurations of perforation pattern, the transmission loss has been computed. The integrated transfer matrix (ITM) approach was used to conduct a 1D (plane wave) analysis in order to assess the transmission loss by using Wave 1D tool. A plug has been placed in the middle of this pipe, and this pipe has been placed at different perforation percentages with four configuration, and the sound transmission loss has been measured with optimized perforation of plug muffler with two different absorptive material and finally compare all the result to achieve optimum transmission loss.