Active Control of a Wing Tip Vortex with a Dielectric Barrier Discharge Plasma Actuator

Abstract

An experimental investigation has been conducted into the active control of a wing tip vortex with a dielectric barrier discharge plasma actuator. The actuator was placed around the wing tip with the momentum added in the opposite direction to that of the cross stream flow. Particle image velocimetry measurements were performed on a low aspect ratio rounded tip NACA 0015 wing in a low speed wind tunnel at a maximum Reynolds number of 2.8 ×10 5 , based on the wing chord. Experiments were performed at various angles of attack. The current strength of the plasma actuator limited the maximum freestream velocity to 15 ms −1 . For low angles of attack (2 • and 6 • ), the near field results showed an increase in vortex size and a reduction in the core circulation when control was applied. The effectiveness of the actuator reduced with freestream velocity and angle of attack. The use of the plasma actuator was found to increase the velocity fluctuations close to the surface of the wing. At an angle of attack of 14 • , the actuator resulted in a smaller vortex and an increase in the core circulation. It was hypothesised that at this high angle of attack, the vorticity generated at the suction side electrodes was fed into the core, increasing the strength of the tip vortex. The results show that the potential of the plasma actuator for the near field control of the tip vortex is promising provided the angle of attack is low. NomenclatureA * Non-dimensionalised bounded within area of integration AR Aspect ratio b w Wing span, m C L Wing lift coefficient c Wing chord, m Re c Reynolds number based on main element chord r Radial distance measured from vortex centre, mm r 1 Radius of vortex, mm r max Maximum radial distance measured from vortex centre, mm S Surface area, m 2 s Wing semi-span, m t w Wing thickness, m U ∞ Freestream velocity, ms −1 v rms Root mean square velocity component in y direction, ms −1 v * θ Non-dimensionalised tangential velocity x, y, z Coorindates measured from model leading edge tip, m y c , z c Vortex centroid, m * PhD Student, Faculty of Engineering and the Environment. Student Member AIAA † Research Fellow, Faculty of Engineering and the Environment, Member AIAA.