Honeywell Seminar July 19, 2007 PLASMA-ENHANCED AERODYNAMICS – A NOVEL APPROACH AND FUTURE...
-
date post
20-Dec-2015 -
Category
Documents
-
view
217 -
download
0
Transcript of Honeywell Seminar July 19, 2007 PLASMA-ENHANCED AERODYNAMICS – A NOVEL APPROACH AND FUTURE...
Honeywell SeminarJuly 19, 2007
PLASMA-ENHANCED AERODYNAMICS – A NOVEL APPROACH AND FUTURE DIRECTIONS
FOR ACTIVE FLOW CONTROL
Thomas C. Corke
Clark Chair ProfessorUniversity of Notre Dame
Center for Flow Physics and ControlAerospace and Mechanical Engineering Dept.
Notre Dame, IN 46556
Ref: J. Adv. Aero. Sci., 2007.
Honeywell SeminarJuly 19, 2007
Presentation Outline:
• Background SDBD Plasma Actuators– Physics and Modeling– Flow Control Simulation– Comparison to Other FC Actuators
• Example Applications– LPT Separation Control– Turbine Tip-gap Flow Control– Turbulent Separation Control
• Summary
Honeywell SeminarJuly 19, 2007
Single-dielectric barrier discharge (SDBD)
Plasma Actuator
• High voltage AC causes air to ionize (plasma).
• Ionized air in presence of electric field results in body force that acts on neutral air.
• Body force is mechanism of flow control.
Ref: AIAA J., 42, 3, 2004
exposed electrode
dielectric
AC voltage source
covered electrode
substrate
The SDBD is stable at atmospheric pressure because it is self-limiting due to charge accumulation on the dielectric surface.
Honeywell SeminarJuly 19, 2007
Flow Response: Impulsively Started Plasma ActuatorPhase-averaged PIV
Long-time Average
t
Honeywell SeminarJuly 19, 2007
Physics of OperationElectrostatic Body Force
D - Electric Induction
(Maxwell’s equation)
(given by Boltzmann relation)
solution of equation -electric potential
E
Body
Force Y Y Y
(x,t)
Honeywell SeminarJuly 19, 2007
Steps to model actuator in flow
• Space-time electric potential,
• Space-time body force
• Flow solver with body force added
Honeywell SeminarJuly 19, 2007
Space-Time Lumped Element Circuit
Model: Boundary Conditions on (x,t)
Electric circuit with N-sub-
circuits
(N=100)
exposed electrode
dielectric
AC voltage source
covered electrode
substrate
Ref: AIAA-2006-1206
Honeywell SeminarJuly 19, 2007
Space-time Dependent Lumped Element Circuit Model (governing
equations)
Voltage on the dielectric surface in the n-th sub-circuit
Plasma current
air capacitor dielectric capacitor
Honeywell SeminarJuly 19, 2007
dx/dt
xmax
Model Ip(t)Experiment Illumination
Model Space-time Characteristics
Honeywell SeminarJuly 19, 2007
Plasma Propagation Characteristics
Effect of Vapp
dxp/dt vs Vapp (xp)max vs Vapp
Model
Model
Honeywell SeminarJuly 19, 2007
Plasma Propagation Characteristics
Effect of fa.c.dxp/dt vs fa.c. (xp)max vs fa.c.
Model
Model
Honeywell SeminarJuly 19, 2007
Numerical solution for (x,y,t)
Model provides time-dependent B.C. for
Honeywell SeminarJuly 19, 2007
Body Force, fb(x,t)N
orm
aliz
ed f
b(x
,t)
-5.08 0.0 5.080.0
1.14
x, mm
y,
mm
-5.08 0.0 5.08
0.0
0.5
1.0
x, mm
| f b |
-5.08 0.0 5.080.0
1.14
x, mm
y,
mm
-5.08 0.0 5.08
0.0
0.5
1.0
x, mm
| f b |
t/Ta.c.=0.2
t/Ta.c.=0.7
Honeywell SeminarJuly 19, 2007
Example: LE Separation Control
Computed cycle-averaged body force vectors NACA 0021 Leading Edge
Honeywell SeminarJuly 19, 2007
Example: Impulsively Started Actuator
t=0.01743 secVelocity vectors 2 = -0.001 countours
Honeywell SeminarJuly 19, 2007
Comparison to Other FC Actuators?
• SDBD plasma actuator is voltage driven, fb~V7/2.
• For fixed power (I·V), limit current to maximize voltage.
• Low ohmic losses.• Flow simulations require body force field (not affected by external flow,
solve once for given geometry).
• “Zero-mass Unsteady Blowing” generally uses voice-coil system.
• Current driven devices, V~I.
• Losses result in I2R heating.
• Flow simulations require actuator velocity field (flow dependent).
Honeywell SeminarJuly 19, 2007
Material Quartz 3.8 Kapton 3.4Teflon 2.0
Imax
Imax
Imax
Imax
Maximizing SDBD Plasma Actuator Body ForceAt Fixed Power
All previous SDBD flow control
Honeywell SeminarJuly 19, 2007
Sample Applications
• LPT Separation Control
• Turbine Tip-Clearance-Flow Control
• Turbulent Flow Separation Control
• A.C. Plasma Anemometer
Honeywell SeminarJuly 19, 2007
LPT Separation Control• Span = Span = 60cm60cm• C=20.5cmC=20.5cm
PlasmaSide
Flow
Pak-B Cascade
Ref: AIAA J. 44, 7, 51-58, 2006 AIAA J. 44, 7, 1477-1487, 2006
Honeywell SeminarJuly 19, 2007
Plasma Actuator: x/c=0.67, Re=50k
ActuatorLocation
Steady Actuator
Sep.
Ret.
Honeywell SeminarJuly 19, 2007
f Ls /Ufs=1
Plasma Actuator: x/c=0.67, Re=50kDeficit Pressure
Loss Coeff. vs Re
200%
20%
Base Flow Unsteady Plasma Act.
Honeywell SeminarJuly 19, 2007
•Document tip gap flow behavior. Document tip gap flow behavior. • Investigate strategies to reduce Investigate strategies to reduce pressure-pressure-
losses due to tip-gap-flow.losses due to tip-gap-flow.•Passive Techniques: How do they work?Passive Techniques: How do they work?•Active Techniques: Emulate passive Active Techniques: Emulate passive effects?effects?
Turbine Tip-Clearance-Flow Control
Approach:
• Reduce losses associated with tip-gap flow
Objective:
Ref: AIAA-2007-0646
Honeywell SeminarJuly 19, 2007
Experimental Setup
FlowPak-B blades:4.14” axial chord
edyn
tetip P
PPc
Honeywell SeminarJuly 19, 2007
Under-tip Flow Morphology
t/g =2.83
t/g =4.30
g/c=0.05
Separation line: Receptive to active flow control.
Tip-flow Plasma Actuator
Honeywell SeminarJuly 19, 2007
Re=500k
0.8 0.9 1
0
0.1
0.2
0.3
0.4
0.5
y/p
itch
No Plasma
z/span
Unsteady Excitation Response
U
lfF
Shear InstabilityShear Instability: 0.01<F+<0.04, U = maximum shear layer velocity, l = momentum thickness: 0.01<F+<0.04, U = maximum shear layer velocity, l = momentum thicknessViscous Jet Core:Viscous Jet Core: 0.25<F+<0.5, U = characteristic velocity of jet core, l = gap size, g 0.25<F+<0.5, U = characteristic velocity of jet core, l = gap size, g
Honeywell SeminarJuly 19, 2007
0.8 0.9 1
0
0.1
0.2
0.3
0.4
0.5
y/pi
tch
No Plasma
0.8 0.9 1
0
0.1
0.2
0.3
0.4
0.5
z/span
F+ = 0.03, (f = 500 Hz)
0.8 0.9 1
0
0.1
0.2
0.3
0.4
0.5
F+ = 0.07, (f = 1250 Hz)
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Cpt
Unsteady Excitation Response: Selected F+
Cpt/Cptbase=0.95 Cpt/Cptbase=0.92
Honeywell SeminarJuly 19, 2007
121
2
11
11
1
ln
ese
te
te
sept
ti
te
ti
te
MP
P
P
Pc
P
P
P
PRs g/c t/g F+ Cpt Δη
No Squealer 5% 2.83 N/A 0.301 --
Squealer 5% 2.83 N/A 0.194 0.7%
Winglet 5% 4.30 N/A 0.247 0.3%
No Actuator 4% 3.52 N/A 0.251 --
Actuator 4% 3.52 0.07 0.232 0.1%
1
1
2
1
1
2
1
exp1
t
t
t
t
PP
PP
Rs
Cpt and Loss Efficiency
Honeywell SeminarJuly 19, 2007
Turbine Tip-Clearance-Flow ControlFuture Directions
“Plasma Roughness” Rao et al. ASM GT 2006-91011
“Plasma Winglet”
“Plasma Squealer”
Active Casing Flow Turning
Suction-side Blade “Squealer Tip”
Honeywell SeminarJuly 19, 2007
Turbulent Flow Separation Control
Wall-mounted hump model used in NASA 2004 CFD validation.
Ref: AIAA-2007-0935
Honeywell SeminarJuly 19, 2007
Baseline: Benchmark Cp and Cf
k- SST best up to x/c=0.9k- best for (x/c)ret
S
S
R
Honeywell SeminarJuly 19, 2007
Turbulent Separation Control:Future Applications
• Flight control without moving surfaces
Miley 06-13-128 Simulation
Plasma Actuator
Low-SpeedSeparated
Flow Region
Reattached Flow Region
BWB Inlet with 30% BLI
Aggressive Transition Ducts
AIAA-2006-3495,AIAA-2007-0884
Honeywell SeminarJuly 19, 2007
Plasma Flow Control Summary
• The basis of SDBD plasma actuator flow control is the generation of a body force vector.
• Our understanding of the process leading to improved plasma actuator designs resulted in 20x improvement in performance.
• With the use of models for ionization, the body force effect can be efficiently implemented into flow solvers.
• Such codes can then be used as tools for aerodynamic designs that include flow control from the beginning, which holds the ultimate potential.
Honeywell SeminarJuly 19, 2007
A.C. Plasma Anemometer
• Flow transports charge-carrying ions downstream from electrodes.
• Loss of ions reduces current flow across gap- increases internal resistance – increases voltage output.
• Mechanism not sensitive on temperature.
• Robust, no moving parts.
• Native frequency response > 1 MHz.
• Amplitude modulated ac carrier gives excellent noise rejection.
Originally developed for mass-flux measurements in high Mach number, high enthalpy flows.
Flow
Principle of Operation:
Honeywell SeminarJuly 19, 2007
Plasma Sensor Amplitude Modulated Output
Velocity Fluctuations
at frequency, fm
ac carrier at fc = ~2 MHz
Plasma Sensor
RF Amplifier
electrode
electrode
Amplitude Modulated
Output
fc fc + fmfc - fm
Frequency DomainOutput
Honeywell SeminarJuly 19, 2007
Real Time Demodulation
FPGA-based digital acquisition board allows host based demodulation in real time.
GnuRadioModulated signal recovered