湍流边界层微小尺度流动结构的精细实验测量

用热线风速仪以高于对应最小湍流时间尺度的分辨率,精细测量风洞中平板湍流边界层不同法向位置的流向速度时间序列信号.用子波分析对湍流脉动速度信号进行多尺度分解,用自相关法得到不同尺度湍涡结构的实际物理时间-空间长度,研究了子波分析的分尺度参数与湍流分尺度湍涡结构实际物理时间尺度的对应关系.并由实验测量得到的耗散尺度及泰勒微分尺度研究了耗散尺度、泰勒尺度等湍流微小尺度在湍流多尺度谱中的定位,分析了它们沿平板湍流边界层法向位置的变化规律,用多尺度条件采样方法提取了湍流边界层中微小尺度流动结构的条件相位平均波形.

Finely experimental measurement of micro-scale flow structures in turbulent boundary layer

The velocity time sequence at different vertical locations in a turbulent boundary layer has been finely measured by IFA300 constant-temperature anemometer with resolution higher than the frequency that corresponds to dissipative scale.Wavelet transform is introduced to perform multi-scale eddy decompositions of velocity fluctuation for turbulent flows.Real temporal-scale length and spatial-scale length of multi-scale eddy structures are obtained by correlation functions of multi-scale wavelet coefficients.The relationship between wavelet scale parameter and real temporal scale of multi-scale eddy structures in turbulence are investigated.Dissipative scale and Taylor micro-scale at different vertical locations in turbulent boundary layer are measured and their positions in wavelet scale spectrum are fixed.The evolutions of dissipative scale and Taylor micro-scale across turbulent boundary layer are studied.The phased-averaged waveforms of micro-scale eddy structures in turbulent boundary layer are extracted by multi-scale conditional sampling method.