Effect of microtab on airfoil transonic buffet onset

A CFD simulation using Reynolds-averaged Navier-Stokes method with SST turbulence was conducted to determine the transonic flow around the NACA0012 airfoil with a microtab installed perpendicularly to the airfoil surface in the vicinity of trailing edge. The influences of different installing schemes of microtabs (one tap installed on airfoil upper surface, one tap installed on airfoil lower surface, two taps were symmetrically installed on airfoil upper and lower surfaces) on transonic buffet onset were analyzed and compared. Subsequently, a sensitivity analysis was conducted to determine the effect of height and chord wise position of microtab on transonic buffet onset. The results indicate that the improvement of the buffet onset angle of attack is achieved by installing the microtab on the upper (suction) surface of the airfoil; furthermore, the buffet onset angle of attack tends to be improved as the height of microtab increases; however, the improvement of the lift coefficient of buffet onset is attained by installing the microtab on the lower (pressure) surface of the airfoil; similarly, the lift coefficient of buffet onset can be improved with the increase in microtab height; the variation of microtab chord wise position has little effect on the buffet onset angle of attack, but it has obvious influence upon the lift coefficient of buffet onset.