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U.S. Air Force Research Laboratory’sU.S. Air Force Research Laboratory s Need for Flow Physics and Control with Applications Involving Aero Optics andApplications Involving Aero-Optics and
Weapon Bay Cavities 23 Aug 09
Dr. Ryan SchmitA E iAerospace Engineer
RBAIAir Force Research LaboratorAir Force Research Laboratory
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https://ntrs.nasa.gov/search.jsp?R=20100018572 2020-06-16T05:23:07+00:00Z
When the Calculations say it should work sometime the Physics doesn’t listen
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filename: 03Movie Clip Public2.wmv
Internal Store Motion Interaction
M, Re, Q
Turbulence
u, v, w
Vibrations
Turbulence
Aircraft Boundary Layer
Aircraft Motion Shear Layer Flow
Control
Store Rack Cavity
AcousticsInternal
Store
Rack Geometry AcousticsFlow Field
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StoreMotion
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Inside a Weapons Bay
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filename: 03bomb-bay.mpg
Consequence
• Store Motion
– Deploys Properly
– Becomes unstable in flight
– Strike aircraft
• Flow Physicsy
– Damage to Aircraft, Equipment and Store
• Mainly from Acoustic levels• Mainly from Acoustic levels
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Flow Control
• Geometry Modification
– Fences, Spoilers, Rod-in-Cross Flow
• Open Loop Control
– Pulsed Blowing, Suction, Plasma
• Closed Loop Controlp
– Feedback Flow Control with Pulsed Blowing
• You name it, it has been tried
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– The shot gun approach
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Flow Physics
• Trisonic Gasdynamic Facility– PIV
• Seeding Methods
– CO2
ViC t Fl id– ViCount Fluid
– Optic Nozzle Blocks
– Seedless PIV
– PSP
• Advance Diagnostic Development Inside a Cavity (ADDICT)
Examine how flow control effects
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– Examine how flow control effects the flow physics at 10% scales cavity
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Near Field Aero Optics Flow Control
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filename: 03Light Sheet.mwv
Background on Aero Optics
Optical Path Lengthy
I t ti f i d
y
OEmerging Distorted Wavefront
Integration of index over path length
Optical Path DifferenceUc
O
Optical Path Difference
The difference between
cx, y, z, t)
x AThe difference between mean and instantaneous OPLOriginal Planar Wavefront
xpws
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s
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Aero-Optic Interactions
M, Re, Q
Turbulenceu, v, w
Ai ftVibrations Aircraft Boundary Layer
Aircraft Motion
Laser Emitter WakeShear Layer Flow
ControlShocks
Near Field Aero Optic
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DistortionsReduce Density Fluctuations to Increase Energy on Target
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Flow Control for Aero-Optics
• Used Shot Gun Approach for Flow Control
– Pulse Blow, Pins, Combustions, etc.
• One of the best but not yet completely proven methods
– Closed Loop Control using Split POD.
• Split POD was developed by Chris Camphouse
• Separate baseline from control flow field properties to produce proper actuation characteristics for Closed Loop Flow Control
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• Provides Flow Physics Knowledge to the Flow Control DeviceApproved for Public Release; distribution unlimited. Public Release Number 88ABW-2009-3664
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Closed Loop Flow Control for Near Field Aero-Optics
Pressure Time Series
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Pressure AutocorrelationApproved for Public Release; distribution unlimited. Public Release Number 88ABW-2009-3664
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Conclusions
• To develop New Flow Control Techniques
– Knowledge of the Flow Physics with and without control
– How does Flow Control Effect Flow Physics
• What Works to Optimize the Design?
– Energy or Work Efficiency of the Control Technique
• Cost - Risk - Benefit Analysis
– Supportability, e.g. (size of equipment, computational power, power supply)
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• Allows Designer to include Flow Control in PlansApproved for Public Release; distribution unlimited. Public Release Number 88ABW-2009-3664
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