Effects of the Actuation on the Boundary Layer of an Airfoil at Reynolds Number Re = 60000

Abstract

Synthetic (zero net mass flux) jets are an active flow control technique to manipulate the flow field in wall-bounded and free-shear flows. The present paper focuses on the role of the periodic actuation mechanisms on the boundary layer of a SD7003 airfoil at $$Re=U_{\infty } C/\nu =6\times 10^4$$ . Here, Reynolds number is defined in terms of the free-stream velocity $$U_{\infty }$$ and the airfoil chord C. The actuation is applied near the leading edge of the airfoil and is periodic in time and in the spanwise direction. The actuation successfully eliminates the laminar bubble at $$AoA=4^{\circ }$$ , however, it does not produce an increase in the airfoil aerodynamic efficiency. At angles of attack larger than the point of maximum lift, the actuation eliminates the massive flow separation, the flow being attached to the airfoil surface in a significant part of the airfoil chord. As a consequence, airfoil aerodynamic efficiency increases by a 124% with a reduction of the drag coefficient about 46%. This kind of technique seems to be promising at delaying flow separation and its associated losses when the angle of attack increases beyond the maximum lift for the baseline case.