吹吸扰动对湍流边界层多尺度相干结构的影响

用IFA-300热线风速仪以高于对应最小湍流时间尺度的分辨率，精细测量了风洞中施加局部周期性吹吸扰动平板湍流边界层近壁区域不同法向和流向位置的瞬时速度的时间序列信号．对平板湍流的扰动是通过平板上沿展向分布的一条窄缝引入的正弦振荡产生的．用子波分析对壁湍流脉动速度信号进行多尺度分解，用子波系数的瞬时强度因子和平坦因子检测壁湍流多尺度相干结构，并提取不同尺度相干结构的条件相位平均波形，研究不同频率的吹吸扰动对平板湍流边界层多尺度相干结构的影响，结果表明，扰动对边界层近壁区域平均速度分布、能量随尺度分布以及多尺度相干结构及其条件相位平均波形，都有显著影响，其中32Hz扰动影响最大．

Effect of Blow-Suction Disturbance on Multi-Scale Coherent Structures in Turbulent Boundary Layer

The velocity time sequence at different vertical and longitudinal locations in a turbulent boundary layer with periodic blow-suction disturbance is finely measured by IFA-300 constant-temperature anemometer with resolution higher than the frequency that corresponds to Kolmogorov dissipative scale. The local forcing on the wall turbulence is given by a sinusoidal oscillating issuing from a thin span-wise slot at the wall. The velocity signals are decomposed into multi-scale eddy structures by nique for multi-scale coherent eddy structures detection from wavelet transform. A conditional sampling techsimultaneous turbulent field is introduced using multi-scale instantaneous intensity factor and multi-scale flatness factor of wavelet coefficients. Phased-average evolution shapes for multi-scale coherent eddy structures in turbulent boundary layer are extracted by this technique. The effect of periodic blow-suction disturbance on multi-scale coherent structures in turbulent boundary layer is investigated. The result shows that periodic disturbance has a remarkable effect on the distribution of mean velocity and energy distribution with scales and on the muhi-scale coherent structures and their conditional phased-average shapes. The effect of disturbance is the most when the frequency is 32 Hz.