Three-dimensional flow control of a wall-bounded wing at Re=20,000

In three dimensional flows, unsteady flow separation can be asymptotically characterized by separation surfaces along which fluid particles well-up normal to a wall surface. These Lagrangian separation surfaces have their footprint in the wall-shear field and we hypothesized to inform the optimal placement of actuators. We test the hypothesis by investigating two control strategies for the unsteady flow over wall-bounded wing numerically simulated at a chordbased Reynolds number of 20,000 and angle of attack of 4°. Firstly, a uniform momentum pulse is applied at the location upstream of the footprint of a nominally two-dimensional laminar separation that covers approximately 90% of the suction side span. Secondly, a jet is placed near the separation point on the end-wall from which a so-called corner vortex originates. The first strategy is shown to enhance lift by optimally enhancing Kelvin–Helmholtz instabilities in the separation surface, effectively promoting a reattachment and lift increase. The second strategy effectively modifies the trajectory of the separation line and associated corner vortex into the recirculation zone which promotes reattachment and improves the aerodynamic performance of the wall-bounded wing also.