小尺度沟槽面边界层湍流参数的测量

利用二维激光多普勒测速仪对零压力梯度下光滑面和小尺度沟槽面的沟槽及峰上部区域中湍流边界层流场进行了对比测量。着重考察了在相同流动条件下两位置的平均速度、流向速度脉动强度、高阶矩以及雷诺剪应力的分布特性。实验中发现 :沟槽能够增加粘性底层的厚度 ,减小壁面剪切力 ,有减阻效应。而此处的流向速度脉动的强度、高阶矩以及雷诺剪应力在距离壁面的某一区域中有减小或降低现象 ,说明沟槽具有削弱湍流湍动的功能 ;而峰上部的湍流统计平均量则表现出与槽相反的结果或趋势。同时还讨论了该沟槽面减阻的原因

Measurement of Turbulent Boundary Layer Over the Grooved - Surface

Measurements of fluid field by means of a two-component laser Doppler velocimetry were carried out in turbulent boundary layers over a micro-grooved surface's valley, peak and a smooth one in a zero pressure gradient. Much attention was paid to the characteristics of the mean velocity, streamwise velocity fluctuation intensity, high-order moment and Reynold shear stress above the valley and peak. The results clearly indicate that the valley is able to increase the viscous sublayer thickness which implies a drag reduction. At the same time, other turbulent statistics such as turbulence intensity, high-order moment and Reynold shear stress decrease different degree respectively, demonstrating that the valley takes a role of weakening turbulence. While the turbulent statistics of the boundary layer over the peak show a contrary tendency. And the reason of drag reduction is also discussed.