Microplasma Actuator for Active Flow Control: Experiment and Simulation
Kazuo Shimizu1, 2, Yoshinori Mizuno2, Akihiko Ito2, Marius Blajan1
1Organization for Innovation and Social Collaboration, Shizuoka University
2Graduate School of Engineering, Shizuoka University

Johoku, Hamamatsu, 432-8561, Japan
E-mail：shimizu@cjr.shizuoka.ac.jp

INTRODUCTIONRESULTSFor active flow control applications, dielectricbarrier discharge (DBD) plasma actuators offer theadvantages such as no moving parts, fast response
due to the electric field and simple construction.
Traditionally plasma actuators are energized atvoltages of tens of kV. Such high voltages are hardto insulate and requires a large size power supply.
Our study was carried out to investigate a micro
scale plasma actuator energized at 1.4 kV. The
numerical simulation of the flow modification was
carried out using Suzen model, which was assumingthat the electric potential of plasma actuator
potential can be split in the potential due to theexternal electric field and potential due to the charge
density of plasma.
By calculating these two potentials the body-forcecould be determined. Furthermore the calculation ofbody force was implemented in the Navier-Stokes
equations and the flow was obtained.

(1)Experimental Results
In the initial part of the discharge the HV1
electrodes were energized at a voltage having duty
ratio 70% and HV2 electrodes were energized at a
voltage having a duty ratio of 30% (D = 70 %). A
diagonal flow was obtained as shown in Fig. 3(a).
After achieving a steady state the duty ratio of thevoltage applied to HV1 electrodes was increased to80% and the duty ratio of the voltage applied toHV2 electrodes was decreased to 20% (D = 80%).
The angle of the diagonal flow changed and after 50
ms it was achieved a steady state as shown in Fig.
3(b).

EXPERIMENTAL SETUP

2.5 ms

Duty ratio 70%

(a)

(a)

(b)
Fig. 3 Flow visualization: (a) Initial state (steady state at D =70 [%]); (b) After 50 [ms] (steady state at D = 80 [%]).

(2) Numerical Simulation
Fig. 4 shows the potential due to the external
electric field, potential due the charge density ofplasma and the resultant body force.
The numerical simulation results (Fig. 5) showedsimilar results with the experimental ones. When
duty ratio was D = 70% the diagonal flow wasobtained as shown in Fig. 3(a). The HV1 electrodes
generated counter clockwise flow with higher flow
velocity and HV2 electrodes generated clockwise
flow with lower flow speed. The duty ratio of D =80% generated a diagonal flow at an angle that
positioned the flow more above the HV2 electrodes
as shown in Fig. 3(b). The velocity of the flow
generated by the HV1 electrodes is higher at D =80%.

10 ms

Duty ratio 70%(b)30 msDuty ratio 70%(c)Fig. 1 Microplasma actuator. Schematic image: top view
showing 20 stripes like electrodes (a); cross-section view (b).

Fig. 1 shows a schematic image of DBD microplasma
actuator. Alternating stripe like electrodes (top-sideelectrode) are placed above a plate like electrode(bottom-side electrode) having a dielectric layer of
25 µm thicknesses in between. The stripe’s width
was 200 µm and thickness was 16µm. The number ofstripe like electrodes was 20. Copper was used forelectrodes and resin film was used for dielectriclayer. Due to the microscale gap, a high electric field(107 ～108 V/m) could be obtained at the top-side
electrode by applying only 1.4 kV. Flow was visualized
by the Particle Image Velocimetry (PIV). Sub-micron
incense smoke was used for tracer particle. Nd YVO4532 nm laser was utilized to visualize the flow. The
phenomena induced by the microplasma actuator, wasmeasured with a high-speedcamera.
(b)

85 ms Steady state(d)Duty ratio 70%
Corresponds to Fig. 3(a)135 ms Steady state(e)Duty ratio 80%
Corresponds to Fig. 3(b)Fig. 5. Numerical simulation of the flow: (a) Initial vortexes;(b) Development of the vortexes; (c) Diagonal flow; (d)Steady state at D = 70 [%]; (e) Steady state at D = 80 [%].

CONCLUSIONS

Fig. 2 Discharge voltage.

Microplasma actuator was energized at low discharge
voltage at about 1.4 kV as shown in Fig. 2. For thesimulation was considered a positive pulse voltage
with amplitude 1 kV and duty ratios of 70% and 80%.
The value of 1 kV corresponds to the effective valueof the AC voltage of 1.4 kV amplitude since therelation between amplitude and effective value isUeffective=Amplitude/√2.

Fig. 4. Electric potential, charge density and body force:
Electrodes upper 1, 3, 6 and 8 from left=1000 V;
Remaining= 0 V.

Microplasma actuator is a simple and efficientsolution for flow control. Due to its size andstructure it can be easily integrated in othercomponents. The experimental results showed thatthe flow could be changed in different directions bymodifying the duty ratio of the voltage whichenergizes different parts of the actuator. When
duty ratio was D = 70% a diagonal flow wasobtained. The angle of the diagonal flow waschanged after the duty ratio was increased to 80%.
The simulation results were in agreement with theexperimental one.