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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 4 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…” 6 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 7 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 12 Planar Shock Topology Quarter-Section Rectangular Analogy Secondary Reflection Secondary Shock Primary Reflection Primary Shock Full Topology 13 Inviscid Results Mach Number along X-Z Centerline Plane 14 Inviscid Results Mach Number along X-Y Centerline Plane 15 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 16 Turbulent Results Mach Number along X-Y Centerline Plane 17 Turbulent Results Mach Number along X-Z Centerline Plane 18 Comparison of Results Mach Number along X-Y Centerline Plane Invisicid Viscous 19 Comparison of Results Mach Number at Exit Plane Invisicid Viscous 20 Swept-Shock Boundary Layer Interaction Isosurface of TKE in Boundary Layer 21 Swept-Shock Boundary Layer Interaction • Separated Boundary Layer • Centerline Vortex • Interaction Flows 22 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 23 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 24 Model Fabrication • Instrumentation location based on CFD predictions • Diagnostics include: - Pressure - Temperature - Surface Oil Flow Visualization 25 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 26