基于壁面主动变形的湍流减阻控制研究

采用谱方法, 对反向控制下壁面主动变形的槽道湍流进行了直接数值模 拟研究. 结果表明, 在壁面最大变形量小于5倍黏性尺度条件下, 压差阻力可略, 摩擦阻力 降低7.6%. 施加控制后, 湍流强度和雷诺应力受到明显抑制, 平均速度剖面对数区上移. 受壁面法向运动的影响, 条带结构强度减弱、尺度变大; 流向涡外移且强度减弱, 其倾斜和 抬起的角度均有不同程度的减小. 壁面变形呈现流向拉长的凹槽结构, 其平均间距 为90倍黏性尺度.

DRAG REDUCTION CONTROL BASED ON ACTIVE WALL DEFORMATION

Direct numerical simulation was performed to turbulent channel flow with active wall deformation under opposition control.It is shown that when the maximum wall displacement is limited within 5 wall units,the pressure drag is negligible and the friction drag can be reduced by 7.6%.Under the control,the turbulence intensity and Reynolds shear stress are suppressed obviously,and the logarithmic region in mean velocity profile is moved upward.Influenced by the vertical motion of the wall,streaky structures are weakened in strength and enlarged in scale.The streamwise vortices moved further away from the wall with weakened strength,and their tilting and twisting angles are both reduced.The wall appears in the shape of streamwise elongated streaky structures with the mean spacing of 90 wall units.