Development of the air blowing and suction technology for control of a turbulent flow on an airfoil

The possibility of using a combined method of control of an incompressible turbulent boundary layer on the NACA 0012 airfoil is studied experimentally and numerically. The method is based on air blowing and suction through finely perforated walls, which are parts of the airfoil. The study is performed for Reynolds numbers $\mathrm{Re}_c=0.7\cdot10^6$ and angles of attack $\alpha$ from $-6$ to $6^\circ$. It is demonstrated that the mechanism responsible for changes in the aerodynamic characteristics of the airfoil is the same for all variants of the control action in the form of air blowing and suction: an increase in pressure due to air blowing on one side of the airfoil and a decrease in pressure due to air suction on the opposite side lead to an increase in the lift force and, finally, to a gain in the lift-to-drag ratio of the airfoil, which reaches three units at $\alpha\approx0^\circ$. Unfortunately, the efficiency of this method of boundary layer control decreases with increasing $\alpha$.