噪声对边界层转捩的影响

Effect of the Noise on Boundary Layar Transition

风洞流场的噪声和湍流度是影响层流边界层转捩实验结果的两个重要因素。本文通过实验初步研究噪声对转捩的影响,实验包括:输入声影响和风洞流场的噪声。本文的结果表明:声频和声压在数值上都存在敏感区,风洞噪声是宽带噪声,以低频为主(至少低速风洞是如此),这对层流边界层转捩有重要作用,风洞噪声会随风速加大而增高;在稳定段用栅格改变湍流度时,实验流场的噪声会随湍流度升高而增加。

In test section of wind tunnel , the stream turbulence and the stream noise are of two important factors effecting experimental results of laminar boundary layer transition . In this paper,an experimental study of stream noise effecting the boundary layer transition is conducted .consisting of two parts : (1)effect of sonic input on the boundary layer transition; (2)measurement of stream noise in test section.Results of this paper show that:there are sensitive region of sonic frequency and pressure effecting the boundary layer transition;frequency band of stream noise in the test section is wide,and the low frequency is dominant and important to effect the boundary layer transition ;Stream noise increases with the wind velocity and turbulence raises with adding grid in settling chamber.