The Performance Simulation And Structure Optimization Of Auto Muffler Based On GT-POWER

As the number of car increases year by year, external vehicle noise pollution has also increased noticeably. In addition, vehicle internal noise affects driving safety and riding comfort. Vehicle noise has become an increasingly hot issue these days and development of auto muffler, an effective tool for reducing vehicle noise, consequently received more and more attention from auto producers.Performance simulation and structure optimization of a muffler using acoustic CFD software are independent on time and place and require limited human and capital input, shortening development time and improving efficiency.GT-POWER software is used in this article for simulation analysis of auto muffler. The research focuses on following two subjects:1. As single-hole resonator only provides effective noise reduction near the resonance frequency, research is done on how a hole in the muffler's resonator baffle affects noise reduction, which reveals that a hole existing in the baffle will form two parallel resonance noise reduction units, expanding the muffler's overall effective frequency band. It is also revealed that a larger hole will shift the frequency band upward. Based on above research, interior noise optimization was conducted on a domestic car. Through source identification, the source of interior booming noise is found to be the exhaust noise. After analysis, a muffler with a hole in resonator baffle was used to replace the previous one and effectively eliminated the interior booming noise, thereby improving NVH performance of the car.2. Based on research on the acoustic four-terminal network, it is assumed different in-line orders of noise reduction units will affect their performance, in that each order has a different acoustic four-terminal network transfer matrix. The assumption is further proven by the acoustic four-terminal network and GT-POWER. On this basis, an intake system was designed for an engine. Four acoustic components were designed for the intake system based on order analysis of the engine's intake noise when the engine is accelerating and no noise reduction components are installed, as well as spectral analysis of the engine running at rated speed. The four components are:an air filter, a quarter wavelength tube and two resonator. Their sizes are also determined. Comparison has been made for the24in-line orders of the four acoustic components to select the best installation order, which has met the noise control target.