【摘要】 利用PIV系统对平板湍流边界层在Reθ=2 167下流向(u′)和法向脉动速度(v′)进行了测量,研究结果显示,当脉动增量的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;当结构函数的阶数为分数且由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。更多还原

【Abstract】 Scaling laws in the wall region of a turbulent flow were addressed by analyzing the moments of velocity increments obtained by the particle-image velocimetry (PIV) system in the boundary layer of a flat plate.The moments of increments of upstream velocity(u′) and longitudinal velocity(v′) were measured at Reθ=2 167 in different wall distances and the scaling of non-integer moments of order between +2 and-1 were discussed.The difference of scaling exponents of low-order structure functions between the experimental data and Kolmogorov’s,SL’s(She & Leveque) prediction increases as the moment order decreases toward-1,which shows that the anomaly is manifested in low-order moments as well.更多还原