Flow Control over a Nonslender Delta Wing by Microsecond Dielectric Barrier Discharge Actuation

The behaviors of a pulsed microsecond dielectric barrier discharge in quiescent air are diagnosed by schlieren image and particle image velocimetry. Some localized pressure waves are induced by the discharge, propagating at a speed of about 348.5 m/s. A fairly weak vortex is also induced, with a maximum velocity of about 0.1 m/s. Wind tunnel experiments are conducted on a wing–body combination with a 47 deg swept wing. Three actuator arrangements are tested by force measurements. For the full leading-edge actuation, obvious changes of the normal forces can be achieved at high angles of attack before stall, when the actuator works at the optimum reduced frequency of F+≈1–2. However, the stall angle is not delayed under the actuation. For front-half actuation at the leading edge, the obvious control effect is obtained at large angles of attack (22–30 deg), while for rear-half actuation, the normal force gets a relatively modest increase at a broad range of attack angles (10–34 deg). The flow pattern obtained by particle image velocimetry shows that the actuation frequency mainly determines the number of chordwise vortices coexisting along the shear layer. It is hard to engender the reattachment vortex over the wing under high-frequency actuations (such as F+=4).