结构声耦合对膨胀腔水消声器声学性能的影响

水消声器可以有效降低管路系统水噪声,为更加准确的预测水消声器传递损失,利用结构声耦合数值模型分析消声器内部声场,研究不同部位结构声耦合效应对充水膨胀腔消声器声学性能的影响规律.计算厚径比为1的充水膨胀腔消声器传递损失,并与刚性条件下的数值结果及理论结果进行比较,以验证方法的正确性;对比二维轴对称模型与整体计算模型的计算结果,验证基于二维轴对称模型分析的可行性.数值研究表明:本方法可以有效的预测水消声器传递损失;随着水消声器腔壁厚度的减小,弹性结构与流体的耦合程度增加,结构声耦合效应对水消声器的声学性能影响增加;周向腔壁的结构声耦合效应会造成膨胀腔消声器的传递损失曲线向低频方向移动;端部腔壁的结构声耦合效应会使消声器传递损失曲线出现反共振峰、共振峰,这与膨胀腔端板结构的固有模态相关;膨胀腔壁的结构声耦合作用使腔内声压在较低频段内出现三维高次波,增加消声量;管路结构声耦合效应对水消声器声学性能的影响不大.

Effects of acoustic solid interaction on acoustic characteristics of water expansion chamber muffler

Water muffler can effectively attenuate the noise of the pipeline system. In order to calculate the transmission loss (TL) of the water muffler accurately, the acoustic field of the water muffler was analysed based on the acoustic solid interaction model. The acoustic solid interaction effect of different structural parts on the acoustic performance of the expansion chamber muffler filled with water was studied. The TL of the water muffler was predicted with the ratio of elastic wall thickness to radius which equals to 1. The obtained results were compared with the analytical solutions and the numerical results of the case with rigid wall, which is used to validate the accuracy of the adopted acoustic solid interaction approach. On the other hand, the results based on the two dimensional axisymmetric model and the complete model were compared to validate the feasibility of the present method. The numerical results show that the decrease of the water muffler''s structure thickness caused the enhancement of interaction between the solid and the water, leading to obvious effects of the elastic wall on the muffler''s acoustic characteristics. The interaction between the circumferential wall and the water made the TL curve of the expansion chamber move to the lower frequency band. The interaction between the end wall and the water caused the resonance peak and the inverse one of the TL curve, which is related to the eigenfrequency of the end chamber wall. The acoustic solid interaction between the expansion cavity wall and the water made the acoustic pressure appear three dimensional high order wave in the lower frequency range, and increased the amount of noise elimination. The interaction between the pipe and the water had little effect on the acoustic performance of the water muffler.