Investigation of blowing and suction for turbulent flow control on a transonic airfoil

Active flow control of compressible turbulent boundary layers on airfoils via wall-normal blowing and suction is studied through a comprehensive parametric study. Wall-normal blowing or suction is applied in different positions on either the suction or pressure side of the transonic airfoil RAE2822 and its effect on the aerodynamic efficiency is investigated. The effect of the angle of attack, Mach number, control magnitude, and control position on the result of the active control are discussed. The compressible flow is simulated via Reynolds-averaged Navier–Stokes equations (RANS) with the open-source solver SU2. The inclusive drag as well as a power budget are introduced and calculated to determine the control configurations that decrease the total drag also accounting for the effort to provide and dump the control fluid. The study shows the promising potential of suction on the suction side in the transonic regime where total net drag savings of 16% were achieved in the investigated parameter range. Contrary to previous results, suction leads to a decrease in the total drag, whereas blowing leads to an increase. The appearance of non-linear effects as the shock wave, which is strongly influenced by the active control, contributes to the different performance compared to previous studies, which mostly considered incompressible flows.