Effect of air blowing and suction through single slots on the aerodynamic performances of an airfoil

Steady air blowing (suction) into a turbulent boundary layer on the NACA 0012 airfoil through singular slots located on its neighboring sides near the trailing edge is studied experimentally and numerically. The investigations are performed at the Reynolds number $\mathrm{Re}_c=0.7\cdot10^6$ in the range of the angles of attack $\alpha$ from $-6$ to $6^\circ$C; the intensity of the injected and sucked jet characterized by a dimensionless momentum coefficient does not reach $10^{-3}$. It is demonstrated that the result of blowing is not only an increase in the lift force, but also significant enhancement of the drag force of the airfoil. In the case of suction, the increase in the lift force is appreciably smaller despite airfoil drag reduction.