Operation of the Aerodynamic Plasma Actuator at High Altitude

Timothy Nichols and Joshua RoveyDepartment of Mechanical and Aerospace Engineering

Missouri University of Science & Technology

Presented to:Thesis Committee

April 24th, 2012

2

Outline

I. BackgroundII. Research ApproachIII. ResultsIV. Conclusion

3

Background• Effects of low pressure environment on actuators:

• Large extension of plasma region• Power consumption increases• Force and effectiveness decrease

4

Background

Dielectric

Decreasing Electric Field

1 atm

• Force production depends on number of ions and electric field• More power going into creating plasma instead of accelerating

it?

EVqnF itotal

5

Research Approach• Spatiotemporal evolution of the surface potential and

electric field found using capacitive probes• Experimentally determine why force decreases• Does calculated average force agree with

experimentally determined force in literature?

6

V-Dot Probes

7

V-Dot Probes

Vac

R (plasma)C3

C2

C1

Dielectric Exposed Electrode (VAC)

R(plasma)

C1

C3

C2

Rint

-+

+18V

-18V

Cint

Vout

8

V-Dot Probes

9

V-Dot Probes

0.4

0.3

0.2

0.1

0.0

Cal

ibra

tion

Fact

or (V

/kV

)

403020100Downstream Distance (mm)

1.0

0.8

0.6

0.4

0.2

0.0

Sign

al A

mpl

itude

(V)

3.02.01.00.0Applied Amplitude (kV)

x = 1.00 mm

x = 2.25 mm

x = 3.50 mm

10

Results

11

Results

760 Torr

88 Torr

12

Results

760 Torr

88 Torr

13

Results3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Ave

rage

Sur

face

Pot

entia

l (kV

)

403020100

Downstream Distance (mm)

760 Torr 429 Torr 321 Torr 226 Torr

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Ave

rage

Sur

face

Pot

entia

l (kV

)

403020100

Downstream Distance (mm)

171 Torr 88 Torr

14

Current Progress

150

100

50

0

Cha

rge

Tran

sfer

red

(µC

/m2 )

403020100

Downstream Distance (mm)

760 Torr 429 Torr 321 Torr 226 Torr

150

100

50

0

Cha

rge

Tran

sfer

red

(µC

/m2 )

403020100

Downstream Distance (mm)

171 Torr 88 Torr

15

Results45

40

35

30

25

20

15

10

5

0

Dow

nstre

am L

ocat

ion

(mm

)

8007006005004003002001000

Pressure (Torr)

Average Surface Potential Average Charge Density

16

Results

17

Results

18

Results

Conclusions• Peak physical charge deposition corresponds closely

with peak surface potential• Electric field remains largely unchanged close to the

exposed electrode edge• Surface potential is spread across surface

• E-Field is zero for approximately 80% of surface at lower pressures compared to 55% at 760 Torr

• 20 times more plasma created at lower pressures than at atmospheric conditions• 88% of this plasma in region with E = 0

• More power into creating plasma than accelerating it19

20

Questions

21

Back-up Slides

22

Back-up Slides

8

6

4

2

0

-2

-4

-6

App

lied

Vol

tage

(kV

)

0.90.80.70.60.50.40.30.20.10.0-0.1Time (ms)

t1 t2 t3 t4

23

Back-up Slides

60

50

40

30

20

10

0

Dow

nstream Plasm

a Extension (mm

)

8007006005004003002001000

Pressure (Torr)

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Pow

er (W

/cm

)

Power Consumed Plasma Extension