Development of a Plasma Actuator with Arc Breakdown in a Magnetic Field

摘要

Ongoing research is presented on the development of an innovative plasma-based flow control actuation technique in which a high-voltage plasma arc is generated across a coaxial pair of electrodes positioned within the field of a strong rare-earth magnet. Generation of the plasma arc within a magnetic field perpendicular to its current path results in a Lorentz force on the charged particles, causing the arc breakdown position to sweep about the center of the coax, forming an apparent plasma disc. Having similarities in concept to microwave-generating cyclotron elements, this new actuator concept has been designated as a "Cyclotronic Plasma Actuator". A key aspect of this concept is the coupling of the thermal actuation of the plasma arc along with the induced swirl component produced by the angular velocity of the Lorentz-forced particles. This concept has potential use in boundary-layer flow control, by embedding span-wise arrays in an aerodynamic surface. The purpose of the device is to alleviate turbulent flow separation, serving as a controllable vortex generator that can be enabled on-demand during particular flight segments (e.g., during takeoff and landing), and disabled during high-speed cruise segments, eliminating the parasitic drag associated with conventional (vane-type) vortex generators. Demonstration and maturation of this technology in the current research and development program pioneers a class of plasma actuators aimed at addressing a well-known problem in active flow control. The recent experimental progress and near-term objectives are overviewed.