变截面微穿孔板吸声特性研究

传统的微穿孔板要获得较佳的吸声性能，需要较小孔径的微孔（〈0．3mm）；在穿孔率不变的情况下，增加板厚，那么板的吸声性能将下降。为了避免这个问题，提出一种新型的微穿孔板结构——变截面微穿孔板。与传统微穿孔板不同，它的微孔的截面积沿其轴向不是恒定的，而是在轴向的一定位置发生突变，从而板存在孔径差异较大的两部分。在马大猷的理论基础上，分析了变截面微穿孔板的吸声特性，并利用传递函数法，通过阻抗管进行了实验。分析和实验结果显示，变截面微穿孔板的吸声性能主要由孔径较小的部分决定，孔径较大的部分主要是增加了板的厚度，对板的吸声性能贡献较小；因此，通过变截面的方法，在增加板厚的同时也能使板维持在较佳的吸声性能水平。

Study on Acoustic Characteristic of Micro-Perforated Panel with Variable Cross-Section

Traditional Micro-Perforated Panel （MPP） requires small diameter of holes over a very thin panel to obtain better property of sound absorption. In the case of constant hole rate, property of the sound absorption will become worse when panel thickness is increased. To avoid this problem, a new structure of MPP is provided. Different from the traditional MPP, cross-sections of holes of this MPP change suddenly in some places along the axes of the holes. In this paper, based on Ma＇s theory 1 -3 ] , an assessment of sound absorption properties of this kind of MPP is presented. Computation results and experimental data of an impedance tube are compared each other. It is found that the performance of absorption of this kind of MPP depends mainly on the portions of the small holes, and the portions of large holes are for increasing the thickness of the plate only. With this method, the sound absorption of the MPP can be kept in a better level when the thickness of the panel is increased.