中文摘要：

利用层析TRPIV测量得到的平板湍流边界层三维三分量速度场数据库,计算得到了平板湍流边界层空间耗散尺度、剪切尺度、泰勒微分尺度、积分尺度等典型空间特征尺度分别为3～5,40～100,20～50,4000个壁面单位,发现耗散尺度随法向位置缓慢增加,剪切尺度在靠近壁面的区域随法向位置变化不明显,积分尺度已不随法向位置变化。按照局部平均速度空间变形率的概念,沿流向分解得到了平板湍流边界层速度场分尺度速度空间变形率。利用空间自相关法得到了平板湍流边界层流向不同尺度湍涡的空间长度,研究发现小尺度情况下,湍涡结构的空间尺度总体上沿法向增大,且在近壁面,展向尺度与流向尺度相当,在湍流边界层外边界之外,湍涡结构的空间尺度逐渐趋于相等;大尺度的情况下,平板湍流边界层中湍涡结构的空间尺度随着法向位置先增加,然后有一个缓慢增加的过程,且总是流向尺度大于展向尺度,法向尺度最小。

英文摘要：

Typical characteristic spatial scales,such as dissipation scale,shear scale,Taylor micro-scale and integral scale etc.in turbulent boundary layer at 3～5,40～100,20～50 and 4000 wall-units,respectively,were calculated by using the 3D-3C database of time series of spatial velocity field measured by tomographic time-resolved PIV.Results show that dissipation scale slowly increases along the wall normal position upwards;while the shear scale in the near wall region does not change significantly with the normal position;the integral scales do not change with the normal position.Multi-scale velocity spatial strain rates along streamwise direction in the velocity field of turbulent boundary layer were obtained according to the concept of spatial strain rates of local average velocity.The spatial lengths in streamwise direction of multi-scale eddies were acquired by using method of spatial auto-correlation.In terms of the small-scale cases,the spatial characteristic lengths of multi-scale eddies are roughly equal along the streamwise and spanwise direction near the flat plate.Then these spatial lengths of eddies increase in general along the wall normal position upwards.However,at outer region of turbulent boundary layer,these spatial lengths gradually become equal.In the large-scale cases,these spatial lengths of eddies increase firstly along the normal position,and then there is a slower increase trend.Furthermore,the streamwise lengths are always greater than spanwise lengths,with the normal lengths minimum.