某矩形空腔在马赫数3的气动噪声特性研究

文中针对某矩形空腔在马赫数3时的空腔气动噪声特性,进行了数值计算与风洞试验研究。数值研究中使用非线性噪声分析(NLAS)方法进行空腔气动噪声计算,可有效捕捉空腔流动的主要特征,例如剪切层、主频等。试验研究表明,在马赫数3时空腔流场中出现比较明显的脉动偏振,且随站位后移,此现象明显加强;长深比5时有比较明显的反馈激励现象,4阶、8阶主频峰值较高易察觉,其他阶主频不强烈;随长深比增加,空腔逐渐变为闭式空腔,主频峰值基本消失,噪声降低明显。

Research on Acoustic Characteristics in a Cavity at Mach 3

In this paper,research on acoustic characteristies in a cavity has been caried out at Mach3 by numerical computation and wind tunnel test. Principal characteristies ,such as the shear layer anddominant frequency , could be effectively captured in the numerical computation via non-linear acous.tic solver ( NLAS) . In addition , several significant phenomena have been found out in the wind tun-nel test. Firstly , eccentric fluctuation of pressure in the cavity emerges at Mach 3 , which gradually en.hances along with the location backwards. Secondly , feedback excitation with high amplitude at 4''and 8 order frequency is obvious when the length depth ration of the cavity is 5. Thirdly , while thelength depth ratio increases,the open cavity gradually changes into close cavity with the dominantfrequeney disappearing and the noise decline.