Phased Plasma Arrays Phased Plasma Arrays for Unsteady Flow Controlfor Unsteady Flow Control

Thomas C. CorkeMartiqua L. Post Ercan Erturk

University of Notre Dame

Sponsors: Army Research

Office

ObjectivesObjectives

• Optimize phased-plasma actuators

for high-speed applications

• Develop models that include

actuator configurations and fluid

response

Plasma Actuator ConceptsPlasma Actuator Concepts

Plasma forms in regions of highest electric field strength

“electrostatic body force”

In 1-D represents a P-grad

Plasma

CathodeDielectricInsulator

a.c. supply

Anodes in parallel circuit

2

2

1E

dxd

B oE

2

2

1EB oE

PE

Electrostatic Body ForceElectrostatic 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

ApproachApproach

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

Electric Field Lines Magnitude of Electric

Field

L

L/10AsymmetricElectrode

Configuration d=0.2L

L

L/10AsymmetricElectrode

Configuration d=0.2L

Magnitude of

Body Force{greater by

30x}

L/10

Net

Bod

y

Forc

e

B/A

Effect of Electrode WidthEffect of Electrode Width

*

B

A

Kapton Film

Teflon Film

Upper Electrode

Lower Electrode

Schematic of ElectrodesSchematic of Electrodes

Additional layers of Kapton film added to limit plasma from forming on both sides of upper electrode

(1) (1)(1) (1) (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

LNffvp 12 12

12

11

f

Flow Visualization Set-upFlow Visualization Set-up

Light

Black Curtain(reduces glare)

Electronics

Camera

Tunnel

smoke

smoke

smoke

Electrode upstream

Electrode downstream

Electrode parallel to flow

FLOW

FLOW

FLOW

UW

y

z

P

0

U

x

x

Flow Acceleration Concept

Total Pressure Probe

O.D = 0.635mm

I.D. = 0.330mm

U - Velocity Profiles

Actuator 1

Single Actuator – DNS

Effect of Actuator L – DNS

U - Velocity Profiles

Actuator 1

U - Velocity Profiles

Actuator 2

U - Velocity Profiles

Actuator 2

U - Momentum

~15% req.

• 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

Phased Plasma Arrays Phased Plasma Arrays for Unsteady Flow Controlfor Unsteady Flow Control

Thomas C. CorkeMartiqua L. Post Ercan Erturk

University of Notre Dame

Sponsors: Army Research

Office

Advantages of Plasma ActuatorsAdvantages 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

*

For nominal full-scale application need values of

Previous research indicates the solid line:

Extrapolation reveals necessary voltage of 6kV, 250Wpeak

Requires 50% increase of existing voltage and power

Actuator InputActuator Input versus

Normalized Momentum CoefficientNormalized Momentum Coefficient

10BVAu

310 C

Symmetricd=40

L

L/2

d

Symmetricd=40

L

L/2

d

Symmetricd=40

L

L/10

d

Symmetricd=40

L

L/10

d

Symmetricd=20

L

L/10

d

Symmetricd=20

L

L/10

d

More Optimized DesignMore 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)

Imperfect Asymmetry:

Plasma on both sides

of upper electrode

smoke

smoke

Doublet Model for Steady Plasma

Source Upstream Source Downstream

Schematic of Experimental Set-upExperimental Set-up

Function Generator

Low-power Amplifier

High-power Amplifier

High-voltage Transformer

Test Plate

Parallel

Digital

Output

CPU

F1

F

F2

Higher Voltage:

Upper Electrode Downstream

smoke