穿孔管阻性消声器横向模态和声学特性计算与分析

应用二维有限元法计算穿孔管阻性消声器的横向模态，利用数值模态匹配法计算其传递损失，推导了相应的公式并编写了计算程序。对于圆形同轴穿孔管阻性消声器的传递损失，数值模态匹配法计算结果与三维有限元法计算结果以及实验值吻合良好，表明了二维有限元法计算穿孔管阻性消声器横向模态和数值模态匹配法预测消声性能的准确性。进而分析孔径、穿孔率、吸声材料的密度和穿孔管偏移对圆形直通穿孔管阻性消声器横向模态和消声特性的影响。结果表明，孔径减小、穿孔率增大，或者穿孔管偏移量增大均能使消声器有效的平面波区域变宽，高频消声效果变好，但中频消声效果变差；增加吸声材料的填充密度则能提高消声器中高频的消声量。

Transversal mode and acoustic attenuation performance analysis of perforated tube dissipative silencers

The two-dimensional finite element method is used to calculate the transversal modes of perforated tube dissipative silencer, and the numerical mode matching method is developed to predict the acoustic attenuation performance. The corresponding formulation is derived and the computational code is written. For a circular concentric configuration, the transmission loss results from the numerical mode matching method, the three-dimensional finite element method and experiment agree well, which demonstrated the accuracy of the 2-D finite element method in calculating the transversal modes and the numerical mode matching method in predicting the transmission loss of perforated tube dissipative silencer, respectively. The numerical mode matching method is then used to investigate the effects of hole diameter, porosity, density of the sound-absorbing material and offset of the perforated tube on the transversal modes and acoustic attenuation characteristics of the circular straight-through perforated tube dissipative silencer. The results showed that smaller hole diameter or higher porosity or bigger offset of perforated tube may lead to wider effective frequency range of plane wave domination, and better acoustic attenuation performance in the high-frequency range, but worse acoustic attenuation performance in middle-frequency range. Increasing the filling density of sound-absorbing material may improve the acoustic attenuation in the mid to high frequency range.