Basic Study on EHD Flow Induced byPulsed Power Microplasma
Yoshinori Mizuno, Marius Blajan, and Kazuo Shimizu
Organization for Innovation and Social Collaboration, Shizuoka University,
3-5-1 Jyouhoku, Hamamatsu, 432-8561, JAPAN; E-mail：shimizu@cjr.shizuoka.ac.jp
Introduction(3) EHD phenomenon by microplasma actuator
Micro particles (diameter 50 µm) weredistributed on the left side of microplasma
actuator in order to observe the EHD
phenomenon. During the discharge period ofplasma actuator, the micro particle wasblown out of the microplasma actuator. Thus
it could be concluded that the plasma
actuator generates kinetic force at surface
region. This micro size plasma actuator could
be used as surface flow modification such as
separation flow control or drag reduction.

For
activeair-flow
controlapplications,dielectric barrier discharge (DBD) plasma
actuators offer advantages such as no moving
parts, fast response due to the fact that areelectrically energized and simple construction.
When to a plasma actuator high voltage isapplied, a high electric field ionizes the air near
the plasma actuator. Ions are drifted by theCoulomb force. While traveling through the air,ions collide with neutral gas molecules andtransfer their momentum to neutral molecules
induced air flow called ionic wind. This kinetic
force induced by Coulomb force is known as
Electrohyorodynamics (EHD) phenomenon.

(a) Positive pulse

DBD Plasma actuator energized by highvoltages such as 10 kV for active flow control
has been studied. In this study, the micro scale
DBD plasma actuator was fabricated andinvestigated. Due to the micro scale gap, ourmicroplasma actuator could be driven at 1 kV,
relativity low voltage.

(a)Before driving(b)After 40 s driving

Experimental Setup(1) Microplasma actuator(c) After 80 s driving (d) After 120 s driving
Fig. 7 micro particle distribution.

(b) Negative pulse
Fig. 4 Waveform of pulse voltage andcorresponding current and power.

Fig. 1 Geometry of microplasma actuator.
Geometry of microplasma actuator in thisstudy is shown in Fig. 1. Alternating stripe likeelectrodes are placed above a plate likeelectrode having a dielectric layer of 25 µmthicknesses in between. As a result, DBD could
begenerated about 1 kV, relativity low
discharge voltage. It contributes make it easily
to insulate of high voltage line or miniaturize
the power supply.

(2) Experimental Setup
Plasma actuator was energized by a highvoltage bipolar pulse. Tracer particle (OD 50µm) was distributed on a plasma actuator andits movements were observed while driving
microplasma actuator.

DBD by microplasma actuator was observed
by applying bipolar high-voltage pulse. Fig. 3
shows a 5 V trigger signal and thecorresponding high- voltage pulse. Whensignal was rising, positive high-voltage pulse
was generated. When signal was falling,negative high-voltage pulse was generated.
Peak voltage was 1 kV and pulse frequency
was 1 kHz .
Pulse width of high-voltage was 3.6 µs. At thehigh-voltage
peakvalue,corresponding
current and power could be up to 5.0 A and4.5 kW, respectively. Energy consumption by
applying one short pulse was about 1 mJ at
both polarity. Average power consumption
was calculated by the product of 2 mJ andpulse frequency of 1 kHz and was estimatedat about 2 W.

Movement of micro particles while driving
microplasma actuator was measured by highspeed camera. Fig. 8 (a) and (b) shows themovement of micro particles before driving
plasma actuator and while driving plasma
actuator, respectively. Micro particles wereblown off and their velocity was about 1 m/sreaching up to 10 mm height by supplying
high-voltage pulse.

(2) Emission spectra(a) Before driving

Fig. 5 Photograph of the light emission from microplasma
actuator.

5Fig. 2 An experimental setup.

Results and discussion(1) Electrical characteristics

Intensity [arb. unit]

4Conclusions

3210250300350400
Wave length [nm]450500Fig. 6 Emission spectra of microplasma actuator inatmospheric air.

Fig. 3 (a) Trigger signal and corresponding high voltage
pulse.

(b) While driving
Fig. 8 Movement of micro particle.

Fig. 5 shows photograph of light emission bydriving microplasma actuator. Light emissionof DBD was observed at edge of the exposed
electrode. Emission spectra were measured
by emission spectrometer during discharge isshown in Fig. 6. Discharge gas was ambient
air thus the highest peaks corresponds to N2
Second Positive Band System and weremeasured at 315, 337, 357, 375, and 380 nm.

In this study, EHD phenomenon induced by
micro-scale plasma actuator was investigatedand following conclusions were obtained
1) Microplasma actuator could be driven at 1
kV pulsed-voltage and its average power
was 2 W.
2) By energizing the microplasma actuator,
micro particles with diameter of about 50µm were blown off from microplasmaactuator with a velocity of about 1 m/s andreaching up to 10 mm height.

Acknowledgement
The authors would like to thank Prof. Sanadaof Shizuoka University and Prof. Yonoda ofThe University of Electro-communications forthe fruitful discussions.