Plasma Catalysis for Enhanced-Thrust Single Dielectric Barrier Discharge Plasma Actuators

Abstract

S INGLE dielectric barrier discharge (SDBD) plasma actuators have been used to manipulate airflows on a variety of lifting and nonlifting bodies (see, for example, the excellent review article by Corke et al. [1]). These actuators, which consist of a pair of offset electrodes separated by a dielectric material, generate a force on the neutral background gas that results in a paraelectric gas flow. Applications include, for example, active delay of separation near the leading edge of airfoils [2,3], delay of airfoil dynamic stall [4,5], reduction of bluff-body drag by delay of separation [6,7], control of separation on turbomachinery blades [8,9], flow control on wind turbine blades [10], and other similar applications. While plasma actuators have been used with some success, as detailed in the literature cited above, their utility is limited by the small force that is generated by the actuators. The thrust generated by state-of-the-art actuators is limited to about 0.10 to 0.20 N per meter of actuator, inducing a velocity that peaks at about 3.0 to about 6:0 m=s [1]. Although their attributes (particularly the ability to be flush-mounted with almost no parasitic drag, very simple implementation, and nomoving parts) make them very attractive for active flow control, it is generally recognized that a significant increase in control authority is needed in order for plasma actuators to be effective for most practical applications. One approach to increasing actuator thrust may be to apply certain heterogeneous catalysts on the surface of the dielectric exposed to the plasma. In this Note, we present the results of recent experiments using titania (TiO2) as a plasma catalyst in which the actuator thrust was seen to increase by as much as 120% relative to the catalyst-free actuator. We discuss possible mechanisms responsible for the enhanced thrust and suggest further experiments which will improve our understanding of the phenomenon.