吹吸扰动控制猝发过程中雷诺应力的实验

采用热线测速技术和双丝边界层热线探针,在风洞中以高于对应最小湍流时间尺度的分辨率,精细测量了平板湍流边界层施加不同频率周期性质量引射前后,不同流向和法向位置的瞬时流向、法向和展向速度分量的时间序列信号.采用流向脉动速度局部平均结构函数模极大值法检测了壁湍流猝发过程中拟序结构不同速度分量和雷诺应力分量的条件相位平均波形.发现在扰动源下游一定范围内,摩擦因数和雷诺应力幅值有所减小,扰动改变了法向或展向脉动速度与流向脉动速度的条件相位平均波形的相位差,使其保持在π/2的奇数倍左右,此时雷诺应力几乎为0,改变了湍流边界层原有雷诺应力的产生和扩散输运机制,抑制了湍流雷诺应力的产生和输运. 

Experiments of Reynolds stress manipulation during burst by blow/suction disturbance

The time sequence signals of instantaneous longitudinal,normal and spanwise velocity components at different vertical locations on the turbulent boundary layer over a flat plate were finely measured by constant temperature anemometry and double-sensor hot-wire probe in a wind tunnel.By the criteria of the module-maximum of locally averaged longitudinal velocity structure function,the conditional phase-averaged waveforms of different velocity components and Reynolds stress were detected during the burst.After disturbance,it is found that the friction coefficients and the Reynolds stress are reduced;the phase-differences between the phase-averaged waveforms of longitudinal vertical velocity and the spanwise velocity components are changed.When their phase differences are about odd times of π/2,the Reynolds stress is depressed to about zero.The mechanisms of production,diffusion and transportation of Reynolds stress are changed in wall-bounded turbulent flow and the Reynolds stresses are restrained to a certain degree.