Abstract: The finite element method is used to analyze the acoustic characteristics of an expansionchamber muffler with its inlet and outlet pipes being coaxial. Its transmission loss (TL) is calculated. The result is compared with that of the onedimensional solutions based on planar wave theory. The limitation of onedimensional planar wave theory is discussed. The acoustic characteristics of eccentric outlet muffler, doubleoutlet muffler and doublecavity muffler are analyzed. The result indicates that the position and the number of outlet can affect the acoustic characteristic of a muffler for higher and medium frequencies; while the doublecavity muffler has high noiseelimination efficiency for lower and medium frequencies.

Key words: acoustics, expansionchamber muffler, transmission loss (TL), finite element method, acoustic characteristic

摘要： 应用有限元法分析进出口管同轴扩张室式消声器的声学性能，计算其传递损失并与一维平面波理论计算对比，分析一维平面波理论的适用范围。通过分析出口管偏置消声器，双出口管消声器和两腔消声器的声学性能表明：出口管位置和数量影响消声器中高频消声性能，而两腔消声器则能明显改善消声器中低频的消声效果。

关键词: 声学, 扩张室式消声器, 传递损失, 有限元法, 声学特性