湍流度对边界层转捩测量的影响

通过实验研究了气流湍流度对边界层转捩各种测量方法的影响,指出:随机信号均方根值法是检测边界层转捩较有效的方法。在转捩过程中随机信号均方根值变化较大且稳定。此外还研究了气流湍流度和不同频率的声波扰动对转捩区速度脉动均方根值分布的影响,指出:存在最大脉动均方根值,其位置在0.2δ高度附近,且不受湍流度和声波扰动影响。

EFFECT OF THE TURBULENCE ON BOUNDARY LAYER TRANSITION MEASUREMENT

An experimental study on the effect of stream turbulence on some measuring methods of boundary layer transition has been conducted, and indicates that the method to measure rms level of random signal is more effective for detecting boundary leyer transition, because in the transition process, the difference of the rms level of random signal is larger and stable. Mean while, in this paper, the effect of stream turbulence and inputing noise with different fregqency of the rms value distribution of velocity fluctuation in the transition region has been studied, and indicates that there is max. rms value of the fluctuation and it is located near 0.2(5 high, in spite of existing the turbulence and noise. Finally, it is suggested that the criterion of indicating the beginning and ending point of transition region must be studied further for the precision of transition region measurement.