1. Phased Plasma Arrays for Unsteady Flow Control Thomas C. Corke Martiqua L. Post Ercan Erturk University of Notre Dame Sponsors: Army Research Office

2. Objectives Optimize phased-plasma actuators for high-speed applications Develop models that include actuator configurations and fluid response

3. Plasma Actuator Concepts Plasma forms in regions of highest electric field strength “electrostatic body force” In 1-D represents a P-grad Plasma Cathode Dielectric Insulator a.c. supply Anodes in parallel circuit PEPE

4. Electrostatic Body Force Electrostatic Body Force has limited effect – giving induced velocities ~3m/s Phasing Plasma Arrays have the potential to increase this by 100 times Roth, Sherman, & Wilkinson – AIAA 98-0328 Post, Erturk, & Corke – January 2001

5. Approach Develop numerical models of the plasma actuators Optimize electrode arrangements Better designs and electronics Improved actuator response and endurance 1. MODELLING 2. FABRICATION AND MEASUREMENT

6. Electric Field LinesMagnitude of Electric Field L L/10 Asymmetric Electrode Configuration d=0.2L

7. L L/10 Asymmetric Electrode Configuration d=0.2L Magnitude of Body Force {greater by 30x} L/10

8. Net Body Force B/A Effect of Electrode Width * B A

9. Kapton Film Teflon Film Upper Electrode Lower Electrode Schematic of Electrodes  Additional layers of Kapton film added to limit plasma from forming on both sides of upper electrode

10. (1) (2) (1) (3)(4)(5)(6) (4) (3) (2) (5) (6) Insulator Upper electrodes supplied with single time series (1) Lower electrodes supplied with time series (2) through (6) Plasma forms where potential is largest (3) and (6) Produces uni-directional plasma motion Lower electrodes Upper electrodes Schematic of two-frequency phased excitation

11. Flow Visualization Set-up Light Black Curtain (reduces glare) Electronics Camera Tunnel

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15. Electrode upstream Electrode downstream Electrode parallel to flow FLOW UWUW yy zz

16. PP 0 UU x x Flow Acceleration Concept

17. Total Pressure Probe O.D = 0.635mm I.D. = 0.330mm

18. U - Velocity Profiles Actuator 1

19. Single Actuator – DNS

20. Effect of Actuator L – DNS

21. U - Velocity Profiles Actuator 1

22. U - Velocity Profiles Actuator 2

23. U - Velocity Profiles Actuator 2

24. U - Momentum ~15% req.

25. Zeroing in on momentum levels estimated for stall control. More accurate actuator calibrations will rely on DPIV. Will begin experiments to consider best reattachment configurations. Further expand DNS simulations. Summary

26. Phased Plasma Arrays for Unsteady Flow Control Thomas C. Corke Martiqua L. Post Ercan Erturk University of Notre Dame Sponsors: Army Research Office

28. Advantages of Plasma Actuators (1)Fully electronic No mechanical parts to fatigue (2)Low mass Low inertial loading (3) Wide-frequency band width Can match most amplified instability frequency (4) High energy density Maintains high energy with small sizes (5)Scalable in size Can be located on or below surface without need for air sources or tubing

29. * For nominal full-scale application need values of Previous research indicates the solid line: Extrapolation reveals necessary voltage of 6kV, 250W peak Requires 50% increase of existing voltage and power Actuator Input Normalized Momentum Coefficient Actuator Input versus Normalized Momentum Coefficient

30. Symmetric d=40 L L/2 d

31. Symmetric d=40 L L/2 d

32. Symmetric d=40 L L/10 d

33. Symmetric d=40 L L/10 d

34. Symmetric d=20 L L/10 d

35. Symmetric d=20 L L/10 d

36. More Optimized Design 2 mil Teflon Dielectric/Insulator Lower electrode edges covered with Kapton film Upper electrode 1/6 width of lower electrode Asymmetric upper electrode spacing Upper Electrode (2mm) Lower Electrode (12mm)

37. Imperfect Asymmetry: Plasma on both sides of upper electrode

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40. Doublet Model for Steady Plasma Source UpstreamSource Downstream

41. Experimental Set-up Schematic of Experimental Set-up Function Generator Low-power Amplifier High-power Amplifier High-voltage Transformer Test Plate Parallel Digital Output CPU F1F1 F F2F2

42. Higher Voltage: Upper Electrode Downstream smoke