用PIV实验研究边界层内结构函数标度律

湍流标度律的变化情况显示了湍流边界层内的流动状况。利用高分辨率、高帧率的粒子图像测速技术（PIV）对平板湍流边界层进行了实验研究。研究结果显示，当脉动速度增量结构函数的阶数为正整数且逐渐增大时，由实验所得的脉动速度增量结构函数的标度指数逐渐偏离K41和SL标度指数，出现奇异标度律；而当结构函数的阶数为正分数时，实验所得的标度指数和K41及SL标度指数较为接近；当结构函数的阶数由0趋向于-1时，实验的标度指数明显偏离K41和SL标度指数，出现奇异标度律。这也说明了用低阶结构函数的标度指数也能说明标度律的奇异性及边界层内存在间歇性。对于法向速度增量和涡量分量来说，不管结构函数的高阶或低阶的标度指数都不随壁面位置的不同而改变，具有普适性。

Experimental research for scaling law in boundary layer by PIV

Scaling laws in wall region of a turbulent flow were addressed by analysing moments of velocity increments obtained by Particle-image Velocimetry （PIV） system in the boundary layer of a fiat plate .The moments of increments of upstream velocity （u＇） ,longitudinal velocity （v＇） and ponderance of vorticity （dv＇/dx） at Reθ = 2167 were measured in different wall distance and the anomaly of the scaling exponents of high-order structure functions with the increasing order of the moments were verified,and the scaling of non-integer moments of order between ＋ 2 and - 1 were discussed. The relative differences of low-order structure function between the measured exponents and Kolmogorov＇ s and SL（ She ＆ Leveque ） predictions increase as the moment order decreases toward - 1, showing that the anomaly is manifested in low-order moments as well .However,the scaling exponents of v＇ and dv＇/dx will not change with different wall distance to the same order structure functions.