Seminars

Experiments in unsteady actuators illustrated separation control abilities in the case of leading edge and dynamic stall. These studies have focused on plasma actuators for unsteady actuation due to their excellent dynamic response characteristics. Plasma actuators are solid state devices characterized by low mass, compact volume, high actuation bandwidth, and high reliability. In particular, recent experimental results on a Rail Plasma Actuator (RailPAc) have demonstrated the actuator's ability to impart a large and scalable body force on quiescent atmospheric air. This device consists of parallel rails flush mounted on an aerodynamic surface with an arc situated in the gap between the rails. When a large current is applied, Lorentz forces accelerate the arc along the rails and the arc motion transfers its momentum to the surrounding air. Experiments were performed to demonstrate static stall alleviation capabilities of the RailPAc in a low speed wind tunnel. The test article consists of a VR-12 airfoil (3 in chord, 40 in span) with a RailPAc array covering 10% of span. The airfoil was mounted in free stream velocities of 10m/s and 20 m/s (Re 40,000 and 80,000). Measurements included velocity measurements using time resolved Particle Imaging Velocimetry (PIV), high speed imaging of the arc transit, aerodynamic force, and current as well as voltage traces of the RailPAc circuit. The data obtained revealed that the RailPAc is capable of suppressing static stall at angles of attack up to 30° with significant span-wise actuation distances. The presentation will include discussion of the RailPAc actuation authority as well as fluid dynamic mechanisms behind static stall alleviation.