NON-THERMAL ATMOSPHERIC PRESSURE NON-THERMAL ATMOSPHERIC PRESSURE PLASMAS FOR AERONAUTIC PLASMAS FOR AERONAUTIC

APPLICATIONSAPPLICATIONS

Richard B. Miles,Richard B. Miles, Dmitry Opaits, Mikhail N. Shneider, Dmitry Opaits, Mikhail N. Shneider,

Sohail H. Zaidi - PrincetonSohail H. Zaidi - PrincetonSergey macheret – LockheedSergey macheret – Lockheed

Alexander Likhanskii – Penn State U.Alexander Likhanskii – Penn State U.

HAKONE XI HAKONE XI

Oleron Island Oleron Island

September 7-12, 2008September 7-12, 2008

OutlineOutline Dielectric Barrier Discharge (DBD) Configuration Performance with Sinusoidal Driver Modeling of Pulse Sustained DC Driven Experimental Set up Visualization technique Surface Charge Effects Surface Charge measurement Bias Switching Experiments Schlieren Movies and results Thrust Stand Tests New Electrode Configuration Conclusions

Offset DBD Configuration for Offset DBD Configuration for

Flow ControlFlow Control

Surface PlasmaSurface Plasma

Limitations of Sinusoidal Limitations of Sinusoidal Driven DBD Control Driven DBD Control

Breakdown occurs randomly during each Breakdown occurs randomly during each cyclecycle

There is a significant backward There is a significant backward component of the thrust during the cyclecomponent of the thrust during the cycle

Thrust is not generated equally in the Thrust is not generated equally in the positive and negative portion of the cyclepositive and negative portion of the cycle

The duty cycle is low – part of the time no The duty cycle is low – part of the time no thrust is being generatedthrust is being generated

Pulse Sustained, DC Driven DBD ConceptPulse Sustained, DC Driven DBD Concept

Dielectric material:kapton tapethickness 100 μm

Electrodes:copper foilwidth 25 mmspanwise dim. 50 mm

The circuit is designed so as to superimpose short pulses on a low frequency bias voltage without interference between the pulser and the low-frequency power supply. The pulses and the bias voltage are controlled independently

Main differences between pulses with arbitrary bias and sine voltage

Sine Voltage Pulses with Bias

Two functions simultaneously:Plasma generation andbody force on the gas

Bias produces the body force

on the gas

Pulses efficiently generate plasma

The parameters of pulse-bias configuration – peak pulse voltage, pulse repetition rate, pulse burst rate, duty cycle,

and both the frequency and amplitude of the time-depended bias voltage – can be varied independently,

greatly increasing flexibility of control and optimization of the DBD actuator

TerminologyTerminology

Terminology used in the paper for the pulse and bias voltage polarities. The encapsulated electrode is always considered to be at zero potential. The sign of potential of the exposed electrode relative to the encapsulated one determines the pulse and bias polarity.

Predicted Streamer Like Ionization withPredicted Streamer Like Ionization with3kV, 4 nsec positive pulses and 1 kV positive DC 3kV, 4 nsec positive pulses and 1 kV positive DC

biasbias

Predicted Average Force with 3kV, 500kHz, 4 Predicted Average Force with 3kV, 500kHz, 4 nsec positive pulses and 1 kV positive DC nsec positive pulses and 1 kV positive DC

biasbias

Predicted Momentum Transfer Predicted Momentum Transfer with 4 nsec pulseswith 4 nsec pulses

Momentum, transfered to the gas

0.0E+00

2.0E-09

4.0E-09

6.0E-09

8.0E-09

1.0E-08

1.2E-08

1.4E-08

0.0E+00 4.0E-07 8.0E-07 1.2E-06 1.6E-06 2.0E-06

Time, s

Mo

men

tum

, N

*s/m

High-V neg. pulse

High-V pos. pulse

Low-V neg. pulse

Blue and green lines correspond to the negative pulses with amplitudes -4.5 and -1.5 kV with positive bias of 0.5 kV, and the pink line corresponds to the positive pulses with 3 kV amplitude and positive bias of 1 kV. FWHM for all pulses is 4 ns. 

Predicted Surface Jet Predicted Surface Jet Generated Vortex with pulse burstGenerated Vortex with pulse burst

Schlieren techniqueSchlieren techniquefor the DBD plasma actuator induced flowfor the DBD plasma actuator induced flow

Schlieren technique, burst mode of plasma actuator operation, and 2-D fluid numerical model coupled together allow to restore the entire two-dimensional unsteady plasma induced flow pattern as well as the characteristics of the plasma induced force.

0.5 m/sec at 17 mm7 m/sec in the plasma region!

x

ResultsResultsDC Bias experimentsDC Bias experiments

Pulses:50 kHz - 20 μs between pulses500 pulses per burst - 10 ms per burst1000 pulses per period - 50 bursts per second

5kV pulse voltage

-2 kV.. +2 kV DC bias voltage

ResultsResultsSurface charge experiments Positive pulsesSurface charge experiments Positive pulses

10 s10 s

20 s20 s

60 s60 s

wipedwiped

0 kV 0 kV →→ +2 kV +2 kV

10 s10 s

20 s20 s

60 s60 s

wipedwiped

First runFirst run

0 kV Bias Voltage0 kV Bias Voltage +2 kV Bias Voltage+2 kV Bias Voltage

ResultsResultsBias switch experimentsBias switch experiments

Switching the polarity of the bias voltage has a dramatic effect on the DBD operation: much faster jets and vortices are generated compared with the constant-bias cases

Reason - accumulation of surface charge on the dielectric

Charge Build-up Along SurfaceCharge Build-up Along Surfacewith Sinusoidal Applied Voltagewith Sinusoidal Applied Voltage

3kHz, 10kV peak-to-peak 3kHz, 10kV peak-to-peak. .

-2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28-200

0

200

400

600

800

1000

1200

1400

1600

Su

rfac

e p

oten

tial,

V

Distance, mm

Non-contacting Trek Model 247-3 Electrostatic Voltmeter with Trek Model 6000B-13C Electrostatic Voltmeter Probe. • Fast response time (less then 3 ms for a 1kV step)• Operating range from 0 to +/- 3 kV DC or peak AC. • Spatial resolution of ~1 mm.

Surface Charge Build up with 2kV DC bias Surface Charge Build up with 2kV DC bias and 4kV pulses at 20 kHzand 4kV pulses at 20 kHz

0 5 10 15 20 25-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

Sur

face

pot

entia

l, kV

Distance, mm

Positive biasZero biasNegative bias

Positive pulses

0 5 10 15 20 25

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

Negative pulses

Su

rfa

ce p

ote

ntia

l, kV

Distance, mm

Positive bias Zero bias Negative bias

0 5 10 15 20 25-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

Sur

face

pot

entia

l, kV

Distance, mm

Positive biasZero biasNegative bias

Positive pulses

0 5 10 15 20 25

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

Negative pulses

Su

rfa

ce p

ote

ntia

l, kV

Distance, mm

Positive bias Zero bias Negative bias

Charge Build-up RateCharge Build-up Rate

-5 0 5 10 15 20

0.0

0.5

1.0

1.5

2.0

Su

rfa

ce p

ote

ntia

l, V

Distance, mm

1 pulse 10 pulses 100 pulses 1000 pulses

Positive pulsesPositive bias

-5 0 5 10 15 20

0.0

-0.5

-1.0

-1.5

Positive pulsesNegative bias

Sur

face

pot

entia

l, m

m

Distance, mm

1 pulse 10 pulses 100 pulses 1000 pulses

-5 0 5 10 15 20

0.0

0.5

1.0

1.5

2.0

Negative pulsesPositive bias

Su

rfa

ce p

ote

ntia

l, m

m

Distance, mm

1 pulse 10 pulses 100 pulses 1000 pulses

-5 0 5 10 15 20

0.0

-0.5

-1.0

-1.5

-2.0

Negative pulseNegative bias

Su

rfa

ce p

ote

ntia

l, V

Distance, mm

1 pulse 10 pulses 100 pulses 1000 pulses

Charge Bleed Off RateCharge Bleed Off Rate

-5 0 5 10 15 20 25 30

0.0

0.5

1.0

1.5

2.0

2.5

0 min 5 min 10 min 15 min 20 min 25 min 30 min

Sur

face

pot

entia

l, kV

Distance, mm

4 kV Negative pulses2 kV Positive bias

-5 0 5 10 15 20 25 30

0.0

-0.5

-1.0

-1.5

-2.0

4 kV Negative pulses2 kV Negative bias

Sur

face

pot

entia

l, kV

Distance, mm

0 min 5 min 10 min 15 min 20 min 25 min 30 min

Single Sided Versus DoubleSingle Sided Versus DoublePositive pulsesPositive pulses

Although some of the pulse bursts do not create a strong wall jet, they still play an important role in the DBD operation. Their task is to discharge/recharge the dielectric surface and thus to increase the efficiency of the other bursts.

Single Sided Versus DoubleSingle Sided Versus DoubleNegative pulsesNegative pulses

In the absence of the pulse burst during the other half-cycle, the induced wall jet speed becomes 2-3 times lower. The wall jets induced by negative pulses evolve into two-vortex formations whereas the ones from the positive pulses do not.

ResultsResultsSinusoidal bias experimentsSinusoidal bias experiments

Bias:60 Hz sinusoidal2.6 kV peak-to-peak voltage

Pulses:50 kHz - 20 μs between pulses208 pulses per burst - 4.16 ms per burst416 pulses per period - 120 bursts per second5kV peak voltage

Totally different from conventional sinusoidal profile!!

ResultsResultsPulse Repetition Rate Positive pulsesPulse Repetition Rate Positive pulses

20 kHz20 kHz

50 kHz50 kHz

100 100 kHzkHz

ResultsResultsPulse Repetition Rate Negative pulsesPulse Repetition Rate Negative pulses

30 kHz30 kHz

50 kHz50 kHz

70 kHz70 kHz

ResultsResultsPulse Voltage Positive pulsesPulse Voltage Positive pulses

3.3 kV3.3 kV

5.0 kV5.0 kV

7.4 kV7.4 kV

ResultsResultsPulse Voltage Negative pulsesPulse Voltage Negative pulses

3.3 kV3.3 kV

5.0 kV5.0 kV

7.4 kV7.4 kV

ResultsResultsBias Voltage Positive pulsesBias Voltage Positive pulses

5 kV5 kV

10 kV10 kV

13 kV13 kV

ResultsResultsBias Voltage Negative pulsesBias Voltage Negative pulses

5 kV5 kV

10 kV10 kV

13 kV13 kV

Scaling with Pulse Repetition Rate

Scaling with Pulse Voltage

Scaling with Bias Voltage

Shielded Thrust StandShielded Thrust Stand

Thrust Measurements withThrust Measurements withHigh Voltage PulsesHigh Voltage Pulses

and Oscillating Bias Voltage Waveformsand Oscillating Bias Voltage Waveforms

0

5

10

Positive pulses Negative pulses Average abs value

of bias voltage, a.u.

Th

rust

, m

N/m

Thrust Dependence on Thrust Dependence on Square Wave Duty Cycle Square Wave Duty Cycle

0 20 40 60 80 1000

2

4

6

8

10

12

Positive pulses Negative pulses

Thr

ust,

mN

/m

Positive bias duty cycle, %

Thrust Dependence with Positive Thrust Dependence with Positive PulsesPulses

Common point: 10kV peak to peak square wave bias, 100Hz, 3kV pulses at Common point: 10kV peak to peak square wave bias, 100Hz, 3kV pulses at 25kHz25kHz

Thrust Dependence with Negative Thrust Dependence with Negative PulsesPulses

Common point: 10kV peak to peak square wave bias, 100Hz, 3kV pulses at Common point: 10kV peak to peak square wave bias, 100Hz, 3kV pulses at 25kHz25kHz

2.0 2.5 3.0 3.50

2

4

6

8

10

12

Thr

ust,

mN

/m

Pulse voltage, kV

0 10 20 30 40 500

2

4

6

8

10

12

14

16

Thr

ust,

mN

/m

PRR, kHz

0 2 4 6 8 10 120

2

4

6

8

10

12

14

16

18

Thr

ust,

mN

/m

Bias voltage, peak-to-peak, kV

1 10 1000

2

4

6

8

10

12

Thr

ust,

mN

/m

Bias frequency, Hz

Summary of Thrust Summary of Thrust MeasurementsMeasurements

0 20 40 60 800

20

40

60

80

100

120

140Sinusoidal voltage profile

6 mil Kapton, 4.4 kHz 4 mil Kapton, 5 kHz 1/4" Quartz, 1 kHz 1/4" Quartz, 2 kHz 1/4" Quartz, 4 kHz 1/4" Quartz, 8 kHz Glass plate, 5 kHz, Thickness unknown

Pulses plus bias voltage profile 1/16" MACOR, 100 Hz square bias

50 kHz 4.5 kV negative pulses 4 mil Kapton, 100 Hz square bias

50 kHz 3.0 kV negative pulses Modified DBD plasma actuator,

4 mil kapton, DC positive bias,10 kHz 3 kV negative pulses

Thr

ust,

mN

/m

Voltage, peak-to-peak, kV

Low Voltage RegionLow Voltage Region

0 5 10 15 20 25 300

10

20

30

40 Sinusoidal voltage profile 6 mil Kapton, 4.4 kHz 4 mil Kapton, 5 kHz 1/4" Quartz, 1 kHz 1/4" Quartz, 2 kHz 1/4" Quartz, 4 kHz 1/4" Quartz, 8 kHz Glass plate, 5 kHz, Thickness unknown

Pulses plus bias voltage profile 1/16" MACOR, 100 Hz square bias

50 kHz 4.5 kV negative pulses 4 mil Kapton, 100 Hz square bias

50 kHz 3.0 kV negative pulses Modified DBD plasma actuator,

4 mil Kapton, DC positive bias,10 kHz 3 kV negative pulses

Thr

ust,

mN

/m

Voltage, peak-to-peak, kV

New DBD Design New DBD Design with Exposed Lower with Exposed Lower

ElectrodeElectrode

Thrust Scaling with New Thrust Scaling with New DesignDesign

0 10 20 30 400

2

4

6

8

10

12

14

16

18

Th

rust

, mN

/m

PRR, kHz0 1 2 3 4 5 6 7 8

0

2

4

6

8

10

12

Th

rust

, mN

/mBias voltage, kV

4 kV positive bias voltage, 3 kV negative pulses 410 kHz PRR, 3 kV negative pulses

ConclusionsConclusions

• Offset dielectric barrier discharges can generate strong surface jets for aerodynamic control

• Using AC to drive the offset DBD is not optimal• Reverse thrust component• Low duty cycle• Uncontrolled plasma formation

• A new voltage waveform, consisting of high-voltage nanosecond repetitive pulses superimposed on a DC voltage was proposed

• The experiments showed that the charge build-up on the dielectric surface shields both the applied DC and AC electric field

• Charge build up was overcome with high voltage pulse sustained plasma and•A high-voltage low-frequency sinusoidal or square wave bias voltage •A partially covered electrode configuration operating with a DC bias

• Bias voltage is the most important parameter for thrust generation