鼓型消声器的声学性能计算与分析

Acoustic attenuation performance of a drumlike silencer

鼓型消声器是由膨胀腔和张紧的轻膜片构成。理论和实验研究表明,在空气输运系统中使用鼓型消声器能够在低频区域内取得较佳的降噪效果。使用Green函数和Kirchhoff-Helmholtz积分来计算矩形管道中膜片的辐射声场,进一步计算得到膜片振动引起的、作用在膜片上的辐射声压和消声器的传递损失。对比验证表明,所提出的解析法的计算结果和有限元仿真结果吻合良好。计算结果表明:通过简单地调节膜片的固有频率不能达到拓宽双腔并联鼓型消声器消声频带的目的;增大膜片和管道的距离将降低鼓型消声器的传递损失;将单腔鼓型消声器分为两个串联腔室后,可以通过长短腔室传递损失曲线的互补实现宽频降噪效果,并且每个膜片所需的优化张紧力下降,但是腔室分离之后低频消声效果将降低。

A drumlike silencer consists of an expansion chamber covered by light membranes under high tension. Theoretical and experimental study showed that introducing a drumlike silencer into a typical air conveying system can achieve a satisfactory quieting effect in a low-frequency region.Here,Green’s function and Kirchhoff-Helmholtz integral were used to solve the sound radiation of a membrane in a rectangular duct.After the vibration velocity of the membrane was obtained,the pressure perturbation induced by the membrane oscillation and the transmission loss of the silencer were calculated.The transmission loss calculated with the analytical method agreed well with that of the finite element method simulation.The results showed that simply adjusting the natural frequencies of membranes can＇t broaden the acoustic attenuation bandwidth of the drumlike silencer with two parallel cavities;and the performance of the silencer may degrade when the distance between the membrane and the duct increases;when the single cavity of a drumlike silencer is divided into two tadem cavities,the TL curves induced by longer and shorter cavities can compensate each other and the broad band acoustic attenuation can be reached,the optimal tension for each membrane can also drop,but the acoustic attenuation performance within a low-frequency region declines.