Flow Control by DBD
Plasma Actuator
Satoshi Kikuchi
Fluid Engineering Lab. (Imao Lab.)
Department of Mechanical Engineering,
Faculty of Engineering, Gifu University
kikuchi@gifu-u.ac.jp

Dielectric-Barrier-Discharge(DBD) plasma actuator
The popular device for flow control
Exposed electrode
Dielectric

Induced flow

High AC voltage
Dielectric barrier discharge⇒ Plasma⇒ Induced flow
Covered electrode

Advantage・ High response
・ Simple structure
・ Low power consumption
etc.

Disadvantage
・Low momentum ofthe induced flowWaveforms of applied voltage(Pulse modulation drive)in stationary air

Continuous flow
Momentum is introduced to the flow.

Pulse modulation driveIntermittent flow
Perturbation is introduced to the flow.

Not effective(Low momentum of the induced flow)

Timing control of flow phenomena is possible.
Effective for separation flow.
⇒ We use this control.

St
1 control example

Wake of a cylinder
Flow

CylinderWake (region of recirculating flow)
behind a solid body

The wake of a cylinder :the staggered arrangement of vortices

Karman vortex street

Karman vortex street
Flow Visualization by smoke wire method(play speed 1/67)without control

Flowcylinder

St
1 control example

Wake of a cylinder
Flowcylinder

Wake (recirculating region)

In Karman vortex street,the arrangement of vortices changes with time.
⇒ Cause vibration and noise

Control the Karman vortex street

Experimental setup
Nozzle of Wind tunnel

5m/s

Cylinder
D=40mm

End plates

Result
Backpressure of cylinder
530

1050

Duty [%]
20100

Pressure coefficient -Cpb

1.5
Base case

DragIncrease
Measurement position

1Decrease

This pressure give anindication of drag.

0.501
Non-dimensional control frequency

C pb 2 pb2
U 0

Stf 

fM DU02Stf

We can control the drag ofcylinder.

Flow Visualization（play speed1/67）

Base caseDrag decrease caseDrag increase caseKarman vortex street disappeares.

Karman vortex street is remaining.

Karman vortex street can be controlled
by the DBD plasma actuator.

2nd control example
Flow separation over a wing
Wing
Important parameter
Angle of attack

Stall

Lift

Flow

Stall angle

Change of lift by the angle of attack

The aim of this control is the prevention of separation.
⇒ Increase of lift force at high angle of attack.

Experimental setup
Actuator

yLoad Cell

U0x

αU0c10m/s

Coveredelectrode Dielectric
ExposedelectrodeEnd PlateHigh Voltage
Power Supply

0.025cAirfoil：NACA0015
Chord length：c=100[mm]Span length：s=150[mm]Aspect ratio：AR=1.5

Flow visualization(high angle of attack)No actuation

Flow separated near
the leading edge

Continuous drive

Pulse modulation drive

Leading edge separation is disappeared.

Result

Lift force coefficientCL

Lift coefficient in varying angle of attack
Non-dimensional control frequency

1・No control
αstall＝13 deg

StMStSt

0.60.6
1.02.02.04.0
4.0

・Continuous drive
αstall＝15 deg
・Pulse modulation drive
αstall＝17 deg

0.5

20 00
α[deg]

No actuation
OffOff Off
Duty100%
Continuous drive
Duty
100%
Duty
100%00%00%
Duty
100%

5

1015Angle of attack

20
α[deg]
The control can delay the stall,and increase maximum lift.

3rd control example
Rectangular jet
Turbulent jets are used in a variety ofindustrial applications such as mixing
and cooling/heating.

Control of the width of the jet

Control of the mixing and cooling/heating

Experimental Apparatus
BlowerSettling ChamberNozzle

Hot wire
laserflow
ScreenCamera

Experimental setup
Detail of the nozzle

Flowyyoxz

h = 10mm

w = 75mm

Detail AElectrodes

Nozzle exit velocity
U0 = 5m/s
Re = U0h/ν=3,300

Result of control
Spread case

Reduced case

(fM=55Hz, Duty=10%, θ=π)

(fM=700Hz, Duty=30%, θ=π)Large vortex is generated in
the up and down, alternately.

Vortex does not become largenear the nozzle
It broke down in a little while.

Close-up view

Wide view

Base case(play speed 1/267)

We can control jet width by DBD plasma actuator.

Conclusion

Pulse modulated drive of the DBD plasma
actuator is effective for the separation flowcontrol.