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.