中文摘要：

运用时分粒图仪（time-resolved particle image velocimetry）对平板边界层中立方体扰动诱导产生的发卡涡涡结构进行了实验测量，得到了立方体扰动尾迹区中展向平面内的速度矢量分布．基于拉格朗日坐标系，运用李亚普诺夫指数对流场中的相干结构进行了辨识，比较欧拉坐标系下的结果发现拉格朗日体系下李亚普诺夫指数场不仅有效地包含欧拉坐标系下涡强所表征的发卡涡涡头信息外，并且能够呈现出涡颈在空间中的分布，能够完全刻画出发卡涡涡结构在展向平面内的信息，还发现李亚普诺夫指数对流场拟序结构的表征有很好的鲁棒性．另外，李亚普诺夫指数场的互相关分析表明诱导产生的发卡涡涡结构随着向下游的传播，其涡头不断抬升，发卡涡涡结构与壁面的倾角也逐渐变大，有效地刻画了拟序结构的空间演化过程．

英文摘要：

The hairpin vortices structure induced by a cubic disturbance with a frequency of 2.1 Hz are investigated by time-resolved particle image velocimetry （TR PIV） from both the Euler and Lagrangian view. Firstly, the hairpin vortices＇ heads could be clearly distinguished form the side-view database, which also indicates that the hairpin heads lift up when convecting down streamwise. Then, the finite-time lyapunov exponents （FTLE） method is utilized to describe the lagrangian hairpin vortices induced by the cubic. It could be seen that FTLE clearly shows both the projection of the hairpin heads and the hairpin necks in the streamwise and spanwise plane. Furthermore, two-point correlation of FTLE at different reference positions along the streamwise indicate that the hairpin vortices statistically with an increasing inclined angle with the fiat plate while they are moving downstream.