旋成体仿生凹环表面减阻试验分析及数值模拟

Experiment and numerical simulation on drag reduction for bodies of revolution using bionic scrobiculate ringed surface

通过风洞试验及数值模拟分析了置于旋成体后部的凹环表面结构对其底部阻力、摩擦阻力及激波阻力的影响。马赫数为1.79、基于旋成体最大直径的雷诺数为1.5×106的风洞试验表明:凹环表面可显著减小旋成体的底部阻力,但却增大了包含摩擦阻力和激波阻力的粘性前部阻力。利用SSTk-ω湍流模型对试验优选模型进行了数值模拟,结果表明:凹环内部低速旋转气流产生的涡垫效应和推动效应致使旋成体的摩擦阻力减小了22.4%,凹环还能减弱外部气流对旋成体截尾底部死水区的抽吸作用,显著降低了底部阻力。但由于凹环对气流的扰动增加了激波阻力,故包含底部阻力及激波阻力的压差阻力减小并不显著,仅为0.4%。

The effects of the scrobiculate rings arranged on the rearward of bodies of revolution on the base drag, skin friction drag and shock wave drag were investigated through wind tunnel tests and numerical simulation. The wind tunnel tests with Ma = 1.79, and the Re = 1.5×10^6 based on the maximal diameter of the body indicat that the scrobiculate ringed surface can reduce the base drag evidently, but it increases the viscous forebody drag including the skin friction drag and shock wave drag. The numerical simulation with SST κ-ω turbulence model shows that the scrobiculate ringed surface reduces the viscous drag by 22. 4% due to the vortex cushioning effect and driving effect produced by the low speed rotating flows formed in the rings. The scrobiculate rings also weaken the pumping action of the external flow on the base dead water region behind the body of revolution, and accordingly the base drag is reduced. However, the rings only reduce the pressure drag by 0. 4% because the rings disturb the external flow and increase the shock wave drag.