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ON THE DESIGN OF HYPERSONIC INLETS
3rd Symposium on Integrating CFD
& Experiments in Aerodynamics
USAFA, CO
20-21 June, 2007
Capt Barry Croker
Executive Officer to the AFRL Vice Commander
Air Force Research Laboratory
Acknowledgements
• Dr. Datta Gaitonde
Ms. Heidi Meicenheimer
Mr. Pete Kutschenreuter
Air Vehicles Directorate, AFRL
• Dr. John Schmisseur
AFOSR
•
DoD HPCMO, ASC MSRC
2
Overview
• USAF High Speed Vision
• Hypersonic Design Process
• JAWS Inlet Program
– Design Methodology
– CFD Verification & Validation
– Experimental Test Program
• Conclusions
3
USAF High Speed Mission
Future Capabilities:
Prompt Global Strike
Long Range Strike
Operationally Responsive Access to Space
Hypersonic flight will enable unparalleled global reach and power
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Challenges of High Speed Flight
Boundary layer
transition on external
surfaces and inlet
Balance engine/airframe
over entire speed regime
Shock/boundary layer
interactions
Mass capture, contraction
limits in inlet
Nozzle over-expansion
at transonic speeds
Isolator performance
Cowl lip drag
and heat transfer and operability
External burning ignition
and flame-holding
Fuel injection drag,
mixing and heat transfer
Nozzle recombination
losses
Key enabling technologies need to be developed to make
sustained hypersonic flight feasible!
5
AFRL Design Core Competency
Engineering
Design Tools
Experimental
Ground Testing
High-Fidelity
CFD
“…to establish a core-competency in hypersonic vehicle inlet design…”
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Engineering Design
SHOCK BOX
R
X2
4
2
0
Y
X1
X
Y0
Z
b
Invisicid Streamtracing
UPSTREAM X-Y PLANE
DOWNSTREAM X-Z PLANE
2
4
2
Y0
X1
1
R
b
R
1
4
3
Y1
3
Z4
X2
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Computational Verification
AVUS
Design Space Exploration
2nd Order Unstructured RANS + SA or BL
FDL3DI
High-Fidelity Analysis
3rd Order Structured RANS + k-
 Euler
Stream Trace Verification
Shock Location
 Turbulent
Viscous Corrections
Nonlinear Effects
8
Centerline X-Y Plane
9
2D Centerline X-Y Plane
10
2D Centerline X-Y Plane
11
JAWS
Inward-Turning, Circular Cross Section
M = 5 - 10
Q  = 1000-1500 psf
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Planar Shock Topology
Quarter-Section
Rectangular Analogy
Secondary Reflection
Secondary Shock
Primary Reflection
Primary Shock
Full Topology
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Inviscid Results
Mach Number along X-Z Centerline Plane
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Inviscid Results
Mach Number along X-Y Centerline Plane
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Viscous Correction
JAWS3 Windtunnel Model - Inviscid/Viscous
1.5
1.0
Y - Inches
Lip
Shk2 Impingement
Shk4 Impingement & Exit
Viscous Shk2 Impingement
Viscous exit
0.5
0.0
0.0
0.5
1.0
1.5
Z - Inches
Boundary layer momentum thickness accounted for through each shock
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Turbulent Results
Mach Number along X-Y Centerline Plane
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Turbulent Results
Mach Number along X-Z Centerline Plane
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Comparison of Results
Mach Number along X-Y Centerline Plane
Invisicid
Viscous
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Comparison of Results
Mach Number at Exit Plane
Invisicid
Viscous
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Swept-Shock Boundary Layer
Interaction
Isosurface of TKE in Boundary Layer
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Swept-Shock Boundary Layer
Interaction
• Separated Boundary Layer
• Centerline Vortex
• Interaction Flows
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Conclusions of CFD
 Overall shock structure well aligned with prediction
 Viscous correction adequate for shock location
 Influence of Swept-Shock Boundary Layer
Interaction could have implications on performance
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Experimental Test Program
• NASA Langley Aerothermodynamics Branch
20” Mach 6 Tunnel
• Originally Planned for May, Slipped to August
• Test Goals:
– Establish inlet starting parameters
– Back-pressure study
– Evaluate on and off design performance
• Angle of Attack/Yaw
• Re & Minf
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Model Fabrication
• Instrumentation location based on
CFD predictions
• Diagnostics include:
- Pressure
- Temperature
- Surface Oil Flow Visualization
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Conclusions & Future Work
• Functional Analytical Design
• CFD to check & improve method
• EFD to verify computations & improve method
Engineering
Design Tools
Experimental
Ground Testing
High-Fidelity
CFD
•
•
CFD on off-design cases
Comparison of CFD & EFD data
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