flow control by dbd plasma actuator - gifu university · flow control by dbd plasma actuator...
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Flow Control by DBD
Plasma Actuator
Satoshi KikuchiFluid Engineering Lab. (Imao Lab.)
Department of Mechanical Engineering,
Faculty of Engineering, Gifu University
kikuchi@gifu-u.ac.jp
Dielectric-Barrier-Discharge
(DBD) plasma actuator
Advantage・ High response
・ Simple structure
・ Low power consumption
etc.
The popular device for flow control
High AC voltage
Dielectric barrier discharge
⇒ Plasma
⇒ Induced flow
Disadvantage・Low momentum of
the induced flow
Covered electrode
Exposed electrode Induced flow Dielectric
Waveforms of applied voltage
(Pulse modulation drive)
Continuous flow Intermittent flow
Timing control of flow phenomena is possible. Not effective
(Low momentum of the induced flow)
Perturbation is introduced to the flow.Momentum is introduced to the flow.
Effective for separation flow.
⇒ We use this control.
in stationary air
Pulse modulation drive
1St 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 streetFlow Visualization by smoke wire method
Flow
(play speed 1/67)
cylinder
without control
1St control example
Wake of a cylinder
Flow
cylinderWake (recirculating region)
In Karman vortex street,
the arrangement of vortices changes with time.
⇒ Cause vibration and noise
Control the Karman vortex street
Experimental setup
5m/s
D=40mm
End plates
Nozzle of Wind tunnel
Cylinder
0 1 2
0.5
1
1.5
Base case
Stf
-Cpb
Duty [%]
5 10 20 30 50 100
0U
DfSt
Mf 2
0
2
U
pC b
p b
Result
Backpressure of cylinder
Drag
Increase
Decrease
Non-dimensional control frequency
Pre
ssu
re c
oef
fici
ent
Measurement position
This pressure give an
indication of drag.
We can control the drag of
cylinder.
Base caseFlow Visualization (play speed1/67)
Drag increase case
Drag decrease case
Karman 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
The aim of this control is the prevention of separation.
⇒ Increase of lift force at high angle of attack.
Wing Important parameter
Angle of attack
Flow
Lift
Stall
Change of lift by the angle of attack
Stall angle
Airfoil:NACA0015Chord length:c=100[mm]
Aspect ratio:AR=1.5
Load Cell
Actuator
End Plate
High Voltage
Power Supply
U0
Span length:s=150[mm]
Experimental setup
Dielectric
Covered
electrodeExposed
electrode
0.025c
U0
y
xα
c10m/s
Leading edge separation is disappeared.
Pulse modulation driveContinuous drive
No actuation
Flow separated near
the leading edge
Flow visualization(high angle of attack)
0 5 10 15 200
0.5
1
α[deg]
CL
10 15 20
0.5
1
CL
α[deg]
St 0.6 2.0 4.0
Off Duty100%
10 15 20
0.5
1
CL
α[deg]
St 0.6 2.0 4.0
Off Duty100%
0 5 10 15 200
0.5
1
α[deg]
CL
0 5 10 15 200
0.5
1 St
0.6 1.0 2.0 4.0
α[deg]
CL
Off Duty 100%
0 5 10 15 200
0.5
1 St
0.6 1.0 2.0 4.0
α[deg]
CL
Off Duty 100%00%00%
No actuation
Duty 100%
StM
Result Lift coefficient in varying angle of attack
Angle of attack
Lif
t fo
rce
co
effi
cien
t
Non-dimensional control frequency
The control can delay the stall,
and increase maximum lift.
Continuous drive
・No control
αstall=13 deg
・Continuous drive
αstall=15 deg
・Pulse modulation drive
αstall=17 deg
3rd control example
Rectangular jet
Turbulent jets are used in a variety of
industrial applications such as mixing
and cooling/heating.
Control of the mixing and cooling/heating
Control of the width of the jet
Experimental Apparatus
Blower
Screen
Hot wireNozzleSettling Chamber
Camera
laserflow
Nozzle exit velocity
U0 = 5m/s
Re = U0h/ν=3,300
y
zy
xoFlow
w = 75mm
h = 10mm
Detail A
Electrodes
Experimental setupDetail of the nozzle
Base case Spread case(fM=700Hz, Duty=30%, θ=π)(fM=55Hz, Duty=10%, θ=π)
Reduced case
Result of control (play speed 1/267)C
lose-u
p v
iew
Wid
e v
iew
Large vortex is generated in
the up and down, alternately. Vortex does not become large
near the nozzle
It broke down in a little while.
We can control jet width by DBD plasma actuator.
Conclusion
Pulse modulated drive of the DBD plasma
actuator is effective for the separation flow
control.
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