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A computational study of flow developments over airfoils with backward-facing steps is conducted to explore the possibility of enhancing aerodynamic performance of the airfoils by vortex generation. The study focuses on the effects of the separated flow and subsequent vortex formation generated by the step on pressure distributions around two airfoil profiles. Step location and size are varied to determine their effect on lift, drag, and L/D ratio. A discussion of the effects and trends of the various step configurations on airfoil performance is presented along with the results that may serve as a reference for employing a control criteria to optimize airfoil geometries during flight.

The flow over a NACA 0015 airfoil with a trailing edge jet (jet flap) is investigated using computational and experimental capabilities to determine the influence of the jet on vortex developments over the airfoil. The computational modeling of steady flow at a Reynolds number of 43,000 at fifteen and twenty degrees indicates that as the jet mass flow rate is increased, the trailing edge jet suppresses vortex development, and in some cases, reattaches the flow. Experimental visualization shows the suppression of vortex structures in both steady and accelerating flow. The trailing edge jet may thus be a possibility for vortex control.

An experimental study is conducted to investigate the vortex developments over high angles of attack flat plate airfoils in an accelerated-decelerated flow. To preform the required experiments, a new experimental system was developed and incorporated into an open return subsonic wind tunnel. The system was employed to visualize the details of vortex structures and processes over and downstream of the airfoils for an angle of attack range between 30° and 90°. While flow acceleration encouraged flow separation and vortex convection, flow deceleration delayed the convection of the primary vortex structures as well as the reverse flow reattachment and shredding. The details provided in the article may help in developing control possibilities of vortical flow over vehicles or structures subjected to accelerating-decelerating motions. Further, the study presents guidelines to develop unsteady flow experimental arrangements suitable for incorporation into steady flow subsonic wind tunnels.