Numerical Study of Active Flow Control on a High-Lift Configuration

This paper presents a comprehensive numerical study of the actively controlled flow on the flap of a generic three-element high-lift configuration. An active flow-control mechanism is applied at a Reynolds number of Re = 1.10(6) to enhance the lift of the airfoil. Both pulsed blowing and a harmonic actuation (zero-net-mass flux) are used and compared. Unsteady Reynolds-averaged Navier-Stokes as well as detached-eddy simulations are conducted. The in-house code ELAN is used for the computations. The main focus lies on three-dimensional aspects. It is investigated whether it is possible to further increase the lift by dividing the actuation slot into two parts. A phase shift between these two actuation segments is applied, and the segments are varied in their spanwise extension. As a result of the actuation on the flap shoulder, the circulation around the whole airfoil, and therefore the lift, is effectively increased. It can be demonstrated that the excitation of longitudinal vortices on the upper surface of the flap results in reattachment of the flow.