穿孔共振腔消声器声学性能研究

Study on Acoustic Performance of Perforated Resonators

穿孔共振腔消声器结构在声学上类似于扩张腔消声器,在截面变化处会产生截止频率以下的非平面波,而腔室长度主要影响内部多维声波传播,从而影响其声学性能。应用有限元法研究消声器腔室内由多维声波传播引起的现象,结果表明,穿孔共振腔消声器腔室长度较短时,在研究频率范围内传递损失曲线只有一个共振吸收峰;腔室长度较长时,由于非平面波的影响,在共振频率以外传递损失曲线还有其他吸收峰值。腔室越长,越容易出现非平面波现象,即使腔室长度较短,低频多维声波也不能完全衰减。长度较短的穿孔共振腔消声器的其他结构参数确定时,其共振频率只与穿孔板参数有关,腔室长度的大小变化不会影响共振频率,只会影响共振腔室内多维声波的传播,从而影响消声器声学性能。

The configuration of perforated resonator is acoustically similar to the expansion muffler,for which the nonplanar sound waves below the cut-off frequency will generate at the sectional area discontinuities.While the length of the chamber mainly affects the propagation of multi-dimensional sound waves,and furthermore it affects the acoustic performance of the resonator.In this paper,the phenomenon caused by multi-dimensional sound wave propagation is investigated by means of finite element method.The results show that the transmission loss curve has only one absorption peak within the studied frequency range when the chamber length of the resonator is short.When the chamber length is longer,due to the influence of non-planar waves,other absorption peaks will appear in the transmission loss curve of the muffler in the range beyond the resonance frequency.The longer the chamber is,the easier the non-plane wave phenomenon appears.When the length of the chamber is short,the multi-dimensional wave propagation cannot decay sufficiently either even at low frequencies.For the short-length perforated resonator with other structural parameters unchanged,its resonance frequency is only related to the perforated plate parameters.The variance of the chamber length does not impact the resonance frequency,but influence the acoustic performance of the muffler by affecting the propagation of multidimensional sound waves in the resonator.