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description
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
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V-Dot Probes
Vac
R (plasma)C3
C2
C1
Dielectric Exposed Electrode (VAC)
R(plasma)
C1
C3
C2
Rint
-+
+18V
-18V
Cint
Vout
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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
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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
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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