Acoustic Mode and Structure Mode Analysis of Heavy Duty Truck Muffler

To reveal the muffler acoustic performances and structure vibration characteristics, the computational fluid dynamical (CFD) model and finite element method (FEM) model were established. Acoustic analysis results show that the muffler not only has complex acoustic vibration modes, but also the mode frequency approximately equals the engine’s incentive frequency at rated speed, so the resonance may occur and the noise eliminating effect will be reduced. Structure vibration modal analysis shows that the muffler system has high natural frequency and the natural frequency is widely distributed. So while the engine runs at rated speed or idling speed, its natural frequencies are close to the engine exhausting incentive frequencies. It is the main cause that the muffler cannot reduce the noise effectively and needs further optimization.