Scaling studies of cyclotronic plasma actuators for active flow control applications

An innovative plasma-based flow control actuator has been developed in recent work. The technique produces a high-voltage plasma arc across a coaxial pair of electrodes positioned within the field of a strong rare-earth ring magnet. Plasma arc generation within a magnetic field perpendicular to the current path results in a Lorentz force on the charged particles causing the arc to sweep about the center of the coax forming an apparent plasma disc. Being similar in concept to microwave-generating cyclotron elements the resulting actuator concept has been designated as a “Cyclotronic Arc-Plasma Actuator”. The innovative aspect of this concept is the coupling of the thermal actuation of the plasma arc filament along with the induced swirl component produced by the angular velocity of the Lorentz forcing. Arrays of this actuator configuration can be applied in boundary layer flow control by embedding the devices spanwise 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 or disabled on-demand (e.g. during takeoff landing) avoiding a parasitic drag penalty during high speed cruise. Demonstration of this technology in the current research effort pioneers a class of plasma actuators aimed at addressing a notorious problem in active flow control. The goal of the ongoing research effort is to demonstrate the impact of these actuators in realistic flows applying the devices in wind tunnel models on UAV platforms. Recent bench testing has been focused on optimizing scaling the actuators developing the capability of operating the actuators as modular arrays for demonstration experiments.