Design and Optimization of Automobile Exhaust Muffler

Yeap, Wei Qing (2023) Design and Optimization of Automobile Exhaust Muffler. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

This research studies an overview of the performance of the double outlet exhaust muffler. The noise produced by automobiles is one component of noise pollution to the environment. One of the main reasons exhaust mufflers are made is to reduce the noise levels of the vehicle to meet the demand levels. Although a muffler’s main purpose is to reduce noise, other problems like backpressure inside the exhaust muffler can also impact the car engine’s efficiency. As a reference model, a standard Hyundai i120 exhaust system is used in this project. SOLIDWORKS software is used in this project to design the double outlet exhaust muffler and ANSYS FLUENT software is used to perform Computational Fluid Dynamics (CFD) for fluid flow simulation analysis as well ANSYS Harmonic Acoustics for transmission loss analysis on the model. The effects of various parameters such as baffle hole number, and baffle cut ratio were investigated to gain a better understanding of the exhaust muffler performance. A convergence test was performed to ensure the double outlet exhaust muffler model is suitable to be used in this study. Validation results showed that the constructed model and the reference model were in good agreement. The results showed that increasing the number of baffle holes can improve the reduction of the pressure loss but the transmission loss efficiency will decreased as well. However, the centre hole baffle with perforated pipe allows more gas to flow without resistance while maintaining the efficiency of the transmission loss. Besides, increasing the baffle cut ratio also improves the pressure loss performance but due to the broader opening of the baffle, the transmission loss is decreased. Throughout the project, the optimized model selection was identified which is model E (baffle cut ratio of 0.50). Model E (baffle cut ratio of 0.50) is the best model if the system needs to eliminate the intermediate and high frequency range sound waves, model E (baffle cut ratio of 0.50) with 51.09 % improvement in pressure loss and 123.22 % improvement in transmission loss.