Controlling the flow past a semicircular airfoil at zero angle of attack using slot suction in one or two vortex cells for attaining extremal lift

Calculations using multiblock computational technologies and a model of shear-stress transport modified with allowance for the curvature of streamlines in turbulent airflow were performed at a zero angle of attack for a semicircular airfoil containing one or two surface vortex cells with slot suction. The results showed evidence of stabilization of a nearly undetached flow and attainment of an extremal lift of $C_y$ = 5.2 and a lift-to-drag ratio of $K$ = 24 with allowance for energy losses for suction in the vortex cells.