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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Click to play animation

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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Click to play animation

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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Click to play animation

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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