微型涡流发生器对超临界翼型减阻机理实验与数值分析

针对安装在超临界翼型后部的微型涡流发生器减阻问题，先用风洞实验测出微型涡流发生器对超临界翼型升阻特性的影响，然后采用RANS方程和κ-ε湍流模型进行数值模拟，分析安装在超临界翼型后部的微型涡流发生器减阻原因。研究发现:微型涡流发生器使下游近壁面处低能气体向上卷起与外层高能气体掺混，近壁面平均湍动能增加、翼型后部脉动压强增大，压差阻力减小；湍流应力由速度梯度、湍流粘性系数和脉动压强共同决定，虽然气流掺混，弦向速度法向梯度减小、湍流粘性系数减小，但展向速度法向梯度和脉动压强增大，湍流应力增大，摩擦阻力增大；微型涡流发生器尺寸很小，完全浸没于附面层内，仅掺混与它高度相当的附面层内流体，对附面层厚度影响小，对翼型升力影响小。

Experimental and CFD study on the mechanism of supercritical airfoil drag reduction with micro vortex generators

Wind tunnel and CFD methods are used to investigate the mechanism of the airfoil drag reduction with Micro Vortex Generators (MVGs). RANS and κ-ε turbulence model are used in CFD calculation. The results indicate that with MVGs, the bottom flow is directed to upper domains and thus the boundary layer flow is mixed. Therefore the averaged turbulence kinetic energy near the wall as well as the fluctuating pressure at the rear increases, so the pressure drag decreases. The gradient of the chord velocity and the turbulent viscosity decrease, but the gradient of the span velocity and fluctuating pressure increase more notably, so the turbulence stress increases and the frictional drag increases. MVGs are too small enough to be submerged in the boundary layer flow, and only mix the boundary layer flow. They have little influence on the height of boundary layer and the lift coefficient.