摘要
利用二维LDV系统对零压力梯度下光滑面和减阻沟槽面湍流边界层流场进行对比测量。着重考察了相同流动条件下光滑面、沟槽面的槽及峰上部区域雷诺切应力的分布特性,并利用象限分析法研究了沟槽面对湍流边界层相干结构的影响。研究发现:减阻沟槽面槽峰增强了雷诺切应力水平,使其上部区域下扫事件的平均强度增强;而槽部则抑制了雷诺切应力水平,削弱了其上部区域下扫事件的强度;沟槽上部区域雷诺切应力水平的降低幅度高于槽峰上的增加幅度。由此可以认为:沟槽的抑制作用抵消了沟槽峰部的增强效果,使得近壁区内动量交换水平减弱,从而,减阻沟槽面的雷诺切应力在总体上表现为减小。
Two-component LDV measurements in a turbulent boundary layer with zero pressure gradient have been performed. Two types of surfaces were investigated： a smooth surface and a drag reduction grooved sudace. Distributions of Reynolds shear stress over ridge and valley of the grooved surface were compared with those above the smooth surface. Quadrant analysis method was employed in analyzing modifications induced in turbulent coherent motions. It is found that Reynolds shear stress is increased above the ridge, and the sweep event enhanced as well, whereas, a contrary trend is observed above the valley. Reduction magnitude due to the existence of groove valley is larger than the increase magnitude caused by groove ridge. As a conclusion, the drag reduction grooved surface weakens the near-wall momentum exchange, and decreases the ovendl turbulent Reynolds shear stress above it.
出处
《实验流体力学》
EI
CAS
CSCD
北大核心
2006年第1期40-44,共5页
Journal of Experiments in Fluid Mechanics
关键词
二维LDV
沟槽面
湍流边界层
冒诺切应力
象限分析
相干运动
two-component LDV
grooved surface
turbulent boundary layer
Reynolds shear stress
quadrant analysis
turbulent coherent motion
