Parametric Optimization of Single Dielectric Barrier Discharge (SDBD) Plasma Actuators* Alexey V. Kozlov, Flint O. Thomas † 20th Aerospace and Mechanical Engineering Graduate Student Conference Notre Dame, Indiana 19 October 2006 Supported by NASA Langley NAG1-03076 by NASA Langley Research Center †Advisor

Motivation and Objectives There has been growing interest in flow control using dielectric barrier discharge plasma actuators in recent years. However, studies regarding optimization of plasma actuators are relatively scarce. The Center for Flow Physics and Control at Notre Dame is involved in the development of single dielectric barrier discharge plasma actuators (SDBD) for several aerodynamic applications of active separation control. Flow control experiments show that the performance of present-day plasma actuators at high freestream velocities (high Reynolds numbers) is not enough. A primary objective is to optimize single dielectric barrier discharge plasma actuator toward growing demands of the flow control science. .

Overview of SDBD Plasma Actuators DBD discharge consists of numerous short-time small-scale microdischarges (streamers) distributed randomly in time and in surrounding air volume Plasma volume charge in the presence of an electric field, E*, results in a body force, Fb. Plasma formation is accompanied by a coupling of directed momentum to the surrounding air.

Dielectric barrier dischage Uniform glow Filamentary form

Plasma body force, power dissipation and maximum induced velocity estimation

The Plasma Generation Circuit High voltage for the excitation of the plasma actuators is obtained from the secondary coil of the transformer. Anti noise filter suppresses radio frequency electromagnetic noise radiation from high voltage wires. Accurate hot-wire measurements in the vicinity of the plasma discharge are now possible.

Schematic of the experimental setup for thrust measurement

Power dissipation versus applied voltage dielectric material: quartz glass (dielectric constant 3.7) dielectric thickness 1/4”, encapsulated electrode width 2”

Thrust versus applied voltage

Thrust versus power dissipation X/D = 10, y/D =2

Relation between voltage, optimal frequency and thrust

Voltage waveform comparison Thrust vs. voltage for ramp (sawtooth) and sinusoidal waveforms

Pitot probe velocity measurements Plasma induced velocity profile

Multiple actuators Thrust vs. applied voltage f =48 Hz Thrust vs. applied voltage Plasma induced velocity profile

Summary & Focus of Current Work Optimize plasma actuator design by consideration of: Increase of dielectric thickness and applied voltage and using optimal frequency greatly improve plasma actuator performance. (2) Experiments clearly show the benefit of using ramp (sawtooth) waveform. Multiple actuators (plasma array) significantly increase the body force and plasma induced velocity. Additional measurements to investigate the influence of the dielectric thickness on the optimal frequency and body force are planned.