一种新的膜结构消声器理论模型

膜结构消声器是用来实现控制管道内的低频噪声.然而,现有的理论模型仅仅对管中的平面波有效.从广义Lighthill方程出发,应用Green函数方法及房间声学的基本理论,建立了任意截面管道内声传播模型,在此基础上重点讨论了圆管内膜结构消声器对声波的降噪作用.该方法避开了复杂的特征值求解以及对奇异性的讨论,是一种有效的计算方法.此外,膜结构背腔的尺寸及膜片本身的参数设计至关重要,否则很难在低频范围内得到较宽的降噪频带.

New theoretical model for drumlike silencer

A new technique called drumlike silencer was used to reduce sound propagations in ducts. However, the corresponding theoretical model is only valid for a plane wave in ducts without flow. A general model for describing the effect of the drumlike silencer in ducts based on generalized Lighthill equation and Green′s function theory was put forward. Compared to the existing work, the present model includes the effect of flow Mach number, higher order modes and duct structure parameters on the sound propagation. The relevant numerical results show that the control of higher order modes in a flow duct will be much more difficult than that of plane waves. Therefore, how to carefully make use of drumlike silencer to suppress the sound propagation with more complicated noise sources is worthy to be further investigated. It is also believed the present model may play some role in the optimum design of drumlike silencer. Besides, the cavity size and the parameter of the drumlike silencer are very impossible to obtain a width bank in low frequency.