一种以涡声理论为基础的声衬的实验研究与分析

本文对一种新型声衬一通气声衬的声学特性进行了实验研究。首先,根据实验装置的实际结构给出了通气声衬反射系数的理论计算公式,并使用不同孔径和穿孔率的穿孔板考察了通气声衬的特性参数随频率和气流速度的变化规律,理论与实验符合得较好,其结果表明:适当地选择声衬的几何参数和气流速度可以使通气声衬在共振频率处的吸声系数达到或接近于1.0。其次,本文对共振式声衬和通气声衬的特性进行了比较,对于大孔径穿孔板,前者的吸收频带较窄,而通过合理选择通气速度,则可以设计出高吸声系数和宽频带的通气声衬。最后,本文还对相同几何参数的穿孔板进行了吹气和吸气的对比实验。

Experimental investigations of perforated liners with bias flow based on sound-vortex theory

Some experimental investigations of the acoustic properties of perforated liners with bias flow are presented in this paper. At first, the reflection coefficient of a perforated liner with bias flow is calculated while considering its real structure on the experimental equipment.By choosing perforated plates of different geometrical parameters, measurements are carried out and the experimental results agree with theoretical results well. Both theory and measurements show that the absorption coefficient of perforated liners with bias flow can reach 1.0, provided that its geometrical parameters and flow velocity are chosen properly. Secondly, perforated liners without and with bias flow are compared with each other in this paper. On the condition that the apertures in the perforations are comparatively large, the former tends to have a narrower absorptive band while the latter has a high absorption coefficient with much wider absorptive band by choosing flow velocity properly. Considering that blowing and suction will have different influence on surface shear flow of perforated liners, the comparative experimental results between blowing and suction are also included in this paper.