关键词: 模态分析, 声学分析, 插入损失

Abstract: A combined muffler consists of collateral pipe and expansion-chamber muffler is designed. The modal and acoustic analysis are carried out by making use of the module of dynamics and acoustics in ANSYS，and then the natural frequency and the insert loss curve are obtained. The natural frequency and the insert loss curve of the collateral pipe muffler and the expansion-chamber muffler are also obtained in the same way. The result of numerical simulation shows that the combined muffler does well in the engine fundamental exhaust noise as well as its low frequency harmonic wave. What’s more，comparing with the single part of collateral pipe muffler and the expansion-chamber muffler，the noise elimination effect of combined muffler improves a lot，which achieves the design requirements. The result of numerical simulation is available to predict the muffler property and then judge whether the structure designs meet the demand or not.

Key words: modal analysis, acoustic analysis, insert loss