旋成体仿生凹坑表面流场控制减阻仿真分析

应用SST k-ω湍流模型对仿生凹坑表面旋成体与光滑旋成体进行了对比数值模拟，解释了仿生凹坑表面减小摩擦阻力和压差阻力的原因以及对旋成体近壁区边界层的控制行为。研究结果表明：来流马赫数为0.4时置于旋成体后部的凹坑表面减小了旋成体8.05%的摩擦阻力，1.9%的压差阻力，总阻力减小了6.24%；仿生凹坑表面通过减小壁面的速度梯度和湍流强度减小摩擦阻力，通过减弱外部气流对旋咸体截尾底部气流的抽吸作用减小底部阻力；凹坑表面对边界层的控制行为表现为凹坑内部的低速旋转气流造成了凹坑内部气流与凹坑外部气流的气一气接触，形成涡垫效应；同时，旋转气流在凹坑底部产生的摩擦阻力作为一种附加动力产生推动效应。

Simulation on Flow Control for Drag Reduction of Revolution Body Using Bionic Dimpled Surface

Numerical simulations on drag reductions for the dimpled and the smooth revolution bodies were performed and compared with SST k-ω turbulence model, to explain the reasons of iriction and base drag reductions on the bionic dimpled surface and the control behaviors to boundary layer near wall of the revolution body. The simulated results show that the dimpled surface arranged on the rear?ward of the revolution body reduces the skin friction drag by 8.05 %, the base drag by 1.9 % and the total drag by 6. 24 % at Mach number 0.4; the dimpled surface reduces the skin friction drag through reducing the velocity gradient and turbulent intensity, and reduces the base drag through weakening the pumping action on the flow behind the revolution body caused by the external flow; the flow con?trol behavior on boundary layer produced by dimpled surface displays that the low speed rotating vor?texes in the dimples like vortex cushions, which segregate the external flow and the revolution body; and the low speed rotating vortexes forming in the bottom of dimples can produce negative skin friction against to the other area, which can be considered a accessional impetus.