Combined Blowing/Suction Flow Control on Low-Speed Airfoils

Abstract

The paper focuses on the application of the blowing/suction technique to control incompressible turbulent boundary layer on 2-D low-speed airfoils. Analysis of the experimental and numerical results obtained with the combined flow control technique through the high-technological perforated sections is carried out. This control method turns out to be a more effective way to improve aerodynamic performance of airfoil compared to isolated forcing. Such technology allows us in the studied conditions to provide an effect, characterized by an increase in the airfoil lift and, ultimately, an increment in lift-to-drag ratio ΔK/Kmax by about 0.06. For all combinations of the control forcing, the simplified mechanism responsible for changes in the airfoil aerodynamic performances is almost identical: the pressure increases due to blowing on one side of the airfoil and decreases due to suction on the opposite side, thus, leading to enhancement of the lift force and, as a consequence, to a gain in the lift-to-drag ratio. Also evaluation of the efficiency of the considered control technique with allowance for energy expenses is given.