Dielectric Barrier Discharge Actuators to Control Goertler Vortices on a Swept Wing

Narrowband excitation of fin buffeting is known to exist on several modern aircraft configurations at high angles of attack. For a fixed angle of attack and model geometry, narrowband peak frequency is a linear function of freestream speed. Under these conditions, counter-rotating vortex pairs conforming to the Goertler vortex mechanism are known to develop and amplify in the flowfield over the wings. This phenomenon is explored for relevance to reverse flow over rotor blades at high speeds as well. A 42-degree delta wing with rounded leading edges is used in a low-speed wind tunnel to confirm the phenomenon. The presence of a non-zero yaw angle can increase the strength of the Goertler vortices and also change the location of maximum intensity. Small fences on the surface have been shown to eliminate these narrow-band fluctuations. Dielectric Barrier Discharge plasma actuators offer a possible means to eliminate the narrowband excitation without obtrusive surface fences. An array of such actuators is used to generate counter-rotating vortices. Incense smoke entrained into the flow is illuminated with a laser sheet from a laser pointer. Video images are used to capture velocity in the potential flow region around the vortices. The induced velocity is used to calculate vortex strength. Scaling laws are used to estimate the frequency of the actuators, as well as the magnitude of the velocity. The scaling estimation shows that a plasma actuator is viable for model-scale configurations. Continuing experiments for the final paper plan to apply the actuator under delta wing high angle of attack operation.