壁面声阻抗抑制空腔噪声数值仿真研究

摘要

There exist complex flow field when air flowing through the cavity structure,,due to the fluctuating pressure and velocity,in certain conditions may induce intense aerodynamic noise,the sound pressure level can reach up to 170dB when the incoming velocity is higher,which is a great threat to thesafety of cavity structure,so looking for noise suppression method is a focus of research.For this purp ose,a numerical investigation of cavity with length-to-depth ration of 6 is conducted.Though analyzing the sound pressure level distribution on the cavity floor,the effect of controllable impedance boundary to cavity's sound pressure is studied.The results indicate that the impedance boundary can suppress aerodynamic noise inside the cavity.And that,it is more effective in sound pressure level reduction in the front range of the cavity than in the rear;the noise produced in the rear is attenuated during its radiating process towards upstream.%当气流流经空腔结构,由于腔内严重的压力、速度等脉动,会诱发强烈的气动噪声,来流速度较高时,声压级甚至可高达170dB,对空腔自身结构安全构成较大的威胁,研究人员开展了大量的空腔噪声抑制方法研究.采用CFD+CAA的混合方法,对长深比L/D=6的空腔在亚音速条件下的流动进行了仿真研究.通过改变空腔底部声阻抗值,考察不同声阻抗值条件下空腔底面的声压级分布,探讨了不同的声阻抗对空腔气动噪声的抑制效果.研究结果表明:采用声阻抗对空腔内噪声有一定抑制效果;空腔前部区域声压级降低幅度比后部区域大;空腔后缘产生的噪声在向前传播过程中有所衰减.