Progress and Challenges in Foundational Hypersonics Research

April 2011

John D. SchmisseurProgram Manager

AFOSR/NA

Air Force Office of Scientific Research

AFOSR

Thanks:Mike Wright, Jim Pittman, and Deepak Bose - NASA

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High-Temperature,Light, Durable

Materials

Optimized Aerodynamicsand Flow Control

Enhanced Ignitionand Combustion

Innovative Flowpaths

Advanced Sensors andCommunications

Advanced Flight Controls,Closed-Loop Optimization Control

Hypersonic Flight:Challenging Science & Integration

Development of Hypersonic Capabilities Requires the

Integration of Contributions from a variety of Disciplines

Thermal Management

Advanced Numerical Simulations and Diagnostics

Hypersonic: High-speed flow regime where energy transfer between the flow and thermodynamic and chemical processes becomes significant

Image Courtesy Kei Lau, Boeing

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Foundational Research:“Building Blocks of a Technology Base”

Goals of Basic/Foundational Science – requires balanced investment• Foster scientific innovation to radically change the status quo

– the “basic” part• Develop and utilize essential science to overcome technology show-

stoppers – the “foundational” part

National Aeronautics R&D Plan

~ $20 MIn current FY

AFOSR – Basic• Aerothermo. & Turbulence• Combustion & Diagnostics• High-Temp. Materials• 3 Science Centers• 1 MURI

Fundamental Aero Hyp• Tools and

Technologies• Airbreathing Space Access

• High-Mass Planetary Entry• 3 Science Centers

• Academic research addresses aerothermo. & high-temp materials

• 2 PSAAP Centers with Hypersonic Topics

• Focus is on Advanced Numerics

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Outline

• Major collaborations and plans

• Challenges and opportunities

• Recent accomplishments

• Emerging game-changers

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A Coherent National Scientific Vision and Coordinated Research Investments

volatile history = eroding skill base

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ASSET, PRIME

Shuttle X-43

Inspired by AF SAB-TR-00-03

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Foundational Research Base

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Unknown Program

Directions

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Stable Base of Expertise

The National Hypersonic Foundational Research Plan• Provide a consistent science and technology base• Ensure the long-term availability of an expert knowledge base• Prepare for planned future hypersonic capabilities• Adopted by the JTOH as the basic research roadmap

Boundary Layer

Physics

Nonequilibrium Flows

Shock-Dominated

Flows

Supersonic Combustion

Objective: Advance Science to Address Critical Phenomena in 6 Thrust Areas

High-Temperature Materials & Structures

Environment-Structures &

Material Interactions

Near Term (2010)Semi-Empirical (Calibrated) Methods for 3-D Flows on Idealized Surfaces

AFRL HIFiRE 1- March 2010Axisymmetric

NASA HyBoLT – 2008-Flat with crossflow on sides – lost during launch

AFRL HIFiRE 5 – 3-D Geometry with significant crossflow

Continuous transition to tech maturation

Prompt Global Strike

Increasing 3-D Complexity

Responsive Space Access

Mid Term (2020)Extend Semi-Empirical Methods to Account for Realistic Surface Conditions

Far Term (2030)Physics-Based (Uncalibrated) Estimation for Actual Systems

NHFRP Goals: Boundary Layer Physics

Experiment

Simulation – artificially tripped

HYTHIRM: Near IR Image of Shuttle Orbiter ~ Mach 9

Orbiter experiments facilitate characterization of real surface effects

Planetary Entry

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U. Texas - Predictive Engineering and Computational Sciences (PECOS) Atmospheric Reentry

Stanford University: The Center for Predictive Simulations of Multi-Physics Flow Phenomena with Application to Integrated Hypersonic Systems

NSSEFF: Candler Thermophysics

CUIP Reentry Aerothermo-dynamics Portfolio

MURI: Fundamental Processes in High-Temperature Gas-Surface Interactions

AFRL/RB Computational Hypersonics Center at U. Michigan

AFRL/RB Midwest Structural Sciences Center at U. Illinois

HIFiREASRP: Scramjet-Based Access to Space – UQ consortium

Hypersonic Academic Research Partnership (HARP)

NHSC: Center for Hypersonic Combined Cycle Flow Physics, UVa

NHSC: Hypersonic Laminar-Turbulent Transition, Texas A&M

Basic Science(AFOSR/NASA)

Network of Academic Hypersonic Research Centers

Uncertainty Quantification & Verification and Validation (NNSA)

Application-Oriented (NASA ESMD)

Multidisciplinary Science and Transitioning 6.1

Research Objectives

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ic D

isci

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NHSC: Hypersonic Materials and Structures, Teledyne Scientific and Imaging

Joint AFOSR-NASA Fundamental Aeronautics Sponsored National Hypersonic Science Centers Extend Collaboration Initiated Under the Foundational Research PlanTotal of $30M in invested over 5 years

Coordinating over $20M in Annual Investment Across DoD, NASA, DoE/NNSA and ASRP

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Collaboration via NATO Research and Technology Organisation

A Rich History of International Collaboration in Hypersonics• WG 18: Hypersonic Experimental and Computational Capability,

Improvement and Validation (1991-1997)

• WG 10: Technologies for Propelled Hypersonic Flight (1998-2002)• AVT 136: Assessment of Aerothermodynamic Flight Prediction Tools

through Ground and Flight Experimentation (2005-2009)• Research community responds to opportunity to report

RTO contributions in international forum• Excerpts from Final Report to appear in

Journal of Progress in Aerospace Sciences

New Opportunities to participate in RTO Collaborations• AVT 205: Assessment of Predictive Capabilities for

Aerothermodynamic Heating of Hypersonic Systems (2012- )

• Led by Doyle Knight (Rutgers U.) and Olivier Chazot (VKI)

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Challenges

Micro-scale phenomena significantly impact macro-scale properties, i.e. the small stuff matters• Rate-dependent processes• “race” of instability growth for laminar-

turbulent transition• excitation/relaxation of internal energy states• material response in extreme environments

Access to the Hypersonic Environment remains exceptionally difficult• No ground test facility duplicates every aspect of flight• a few come close… • Flight Research seems to be a lost art• a few programs seek to provide scientific flight data

Technology priorities have shifted• The Cold War was driven by aerospace• Current interests: cyber-tech, socio-cultural, efficiency

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RotationalVibrational Electronic Reactions

Glass-Forming Ablator in ShearCourtesy Mike Wright, NASA Ames

Simulation from H. Fasel, U. Az.

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Opportunities

Unprecedented Insight Into Critical Phenomena• driven by large-scale computing and optical diagnostics

There is No Mature Industry Base for Hypersonic Systems• opportunity to rapidly transition science breakthroughs for integration into emerging systems!

DNS of SBLIP. Martin, U. Maryland

M=3 Nozzle With Hemisphere Body

Fletcher and Chazot, VKI

Spectroscopic Measurement of Transient Material Response

W. Rich, W. Lempert, and I. Adamovich Ohio State

Point measurement of vibrational and rotational/translational temperatures in less than 200 psec sampling time

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Coming Soon?: Flying the Mission – In Silica

81 million element, shock-tailored grid

Experiment

Simulation – artificially tripped

HYTHIRM: Near IR Image of Shuttle Orbiter ~ Mach 9

Surface Heat Flux and Instantaneous Flow Structure on an Elliptic Cone- 32M elements

Large-Scale Numerical Simulations Provide Unprecedented Insight Into Detailed Flow Physics• Massively parallel processing has dramatically

shortened run time – possible to “fly” mission• 230M element solution in 12-24 hours on 288 nodes• 0.5B element solution in ~12 hours on 4k nodes

Simulations Courtesy G. Candler, U. Minnesota

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HIFiREHypersonic International Flight Research Experimentation

$56M AFRL/Australian DSTO Collaborative Effort for Flight Research Exploring Critical Fundamental Phenomena

9 Flights Exploring Critical Science

International Partnership Provides Opportunity for Scientific Flight Research

Integrating All Resources

Experiment Computation

Flight Research

HIFiRE-0May 2009

HIFiRE-1Mar 2010

Risk reduction

Demonstrated flight software

BLT

SBLI

TDLAS

HIFiRE-5

3D BLT

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HIFiRE Flight 1 provides unprecedented insight into unsteady phenomenaR. Kimmel and D. Adamczak, AFRL/RB

Tunnel Expt - Dolling and Murphy

Note: Dissimilar Scales

Preliminary Results: Both transition and SBLI data reveal intermittent signals. Believed to be first such flight measurements for both phenomena.

International Partnership Provides Opportunity for Scientific Flight Research

Wind Tunnel Schlieren

Shock/Boundary Layer InteractionLaminar-Turbulent Transition

Co-ax TC< 10 Hz

Vatell HT1 kHz

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Aeroheating Uncertainty Assessment

Four Mission Relevant Problems

1. Compression Corner Turbulent Flow Mach 7 and14

2. Impinging Shock Turbulent Flow Mach 7 and14

3. High Mass Mars Entry Turbulent Flow Speed: 7 km/s

4. High Speed Return To Earth Turbulent Flow Speed: 15-16 km/s

Uncertainty assessed by a Panel of NASA Subject Matter Experts

Details will be presented at the 42nd AIAA Thermophysics Conference, Jun 27-30, Honolulu, HI

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Exploring the Effect of Roughness on Laminar-Turbulent Transition

• Measurements in thick laminar wall boundary layer allow increased spatial resolution, Mach 6 freestream

Joint Experimental-Computational Effort Yields First Detection of Roughness-Induced Instability at High Mach NumbersB. Wheaton and S. Schneider / Purdue U. - NASA/OSR

M.Bartkowicz and G. Candler / U. Minn - OSR/NSSEFF

DNS of Cylinder in Tunnel Wall Boundary Layer- Uses new low-dissipation numerical scheme

• 21 kHz signal first seen in experiments

• Computations reproduced instability and identified source

• Later experiments verified presence of instabilities predicted by computations at source

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Supersonic flow impacts the upper edge of the roughness

Temperature contour on centerline

Exploring the Effect of Roughness on Laminar-Turbulent Transition

Numerical Schlieren image on centerline

Numerical Simulations Identify Source of Roughness-Induced InstabilityM.Bartkowicz and G. Candler / U. MinnB. Wheaton and S. Schneider / Purdue U.

Experiment confirmed prediction of 21 kHz disturbance upstream of roughness element

Unsteady jet forms, creating unsteadiness in upstream vortex structure

Pressure gradient causes fluid to accelerate away from the high pressure region

Disturbances created upstream then travel downstream and grow

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Creating New Testing Capabilities

Recent-Developed Basic Research Methods Rapidly Transitioned to Revolutionize Ground Test of Major National ProgramsJ. Lafferty/ AEDC, G. Candler/ U. Minn. and S. Schneider / Purdue

Integrated Computations and Experiments provide unprecedented insight into sources and impact of critical aerothermodynamic phenomena

U. Minn. AEDC

Falcon HTV-2

High-Fidelity Numerical Methods yield detailed insight into physics

Innovative fluctuation measurements - Purdue

Temperature-Sensitive Paint provides global heating

AEDC Tunnel 9

Primary Test

Article

Low-Frequency Acoustic Pitot Probe

High-Frequency Acoustic Pitot Probe

Purdue /Sandia Transition Cone

Hemisphere Heat-Transfer Probe

Temperature Sensitive

Paint

Auxiliary Model

SupportFocused schlieren image of BL transition obtained on 7° transition cone at Mach 10, Re/L = 2.0×106/ft

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High-fidelity Ablator Modeling

• Fundamental studies: Monte-Carlo simulation of the ablation at the fiber scale

• High-fidelity ablator model formulated at the macroscopic scale

• Implementation in PATO-modular 3D CFD toolbox

• state-of-the-art already reached and passed; high-fidelity model 50% implemented

Next steps•First release of PATO: October 2011•Second release of PATO with UQ module:

October 2012•Coupling to hypersonics CFD tools: Oct. 2013•Full release of the high-fidelity PATO suite in

Oct. 2014.

Monte-Carlo simulation : Oxidation of the char layer of a low density carbon/phenolic composite (Stardust’s peak heating conditions)

PATO simulation : Ablation of a PICA cylinder, 1MW/m², 30 seconds, NASA Ames X-Jet (off-centered)

High-Fidelity Ablator Modeling

Multi-scale, Multidisciplinary Modeling Advances Ablator Simulations

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Advanced Ablators

Technical Considerations• Utilize flexible fibrous substrate systems• Modify polymer resin systems for increased

flexibility• Incorporate endothermic additives and

radiation inhibitors• Utilize multi-scale modeling to inform

processing and design approaches for advanced TPS

•Utilize commercially available constituent materials

• Incorporation of additives for tailored properties

•Extensive arcjet testing required for TPS maturation

6-inch radius6-inch radius

3-inch radius3-inch radius

Conventional Configurations

NASA Program Advances Mission-Tailored Ablator Families

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MURI: Fundamental Processes in High-Temperature Hypersonic Flows

University of Minnesota, Penn State University, Montana State University, University of Arizona, and University of Buffalo

Approach

Graham V. Candler, Don Truhlar, Adri van Duin, Tim Minton, Deborah LevinTom Schwartzentruber, Erica Corral, Dan Kelley and Paul DesJardin

•Use detailed quantum mechanics to develop accurate force fields for key processes

•Train reactive force field for MD simulations of post-shock wave flows and gas-surface interactions

•Extend to continuum models with DSMC models and state-specific simulations

•Perform experiments at all scales to provide validation data for model generation

Molecular Dynamics

High-Fidelity, Large-Scale CFD

MURI Explores Molecular scale Kinetic Processes to Advance Simulation of Vehicle Scale PhenomenaIntegration of Aerothermodynamics, Chemistry and Materials Research to develop advanced models for gas-surface interactions

Reaction Dynamics Experiments

Reactive Force Fields

Material Surface Effects

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Rethinking the Approach to Turbulence

Spark-Ignited Methane-Air

Orion Nebula

Non-Kolmogorov Turbulence: “Injecting energy into critical scales of the reactive-flowsystem must alter the system’s behavior ...”E. Oran, Naval Research Laboratory

Randomly Forced Broadband Turbulence•Energy spectrum can have a number of envelopes, including k-5/3 typical of Kolmogorov spectra

•Higher moments, such as vorticity or enstropy can behave differently

• Intermittancy is suppressed

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InstabilityAcoustic Absorption

diffusive transport of chemical energy

transport ofthermal energy

Surface Heat Transfer Equation

Changing the Technology ParadigmAn Opportunity for Transformation

Control the gradient via boundary layer management

Improve models for energy transfer

How can we actively control energy transport to optimize system performance?

Control T via energy management

Reliable models for Gas-Surface Interactions

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Exploring Transition Control Via Energy Transfer to Internal Modes

Transition Delay Resulting from CO2 Injection in Boundary Layer Provides Potential Mechanism for Control I . Leyva, AFRL/RZ

J. Shepherd and H. Hornung, Cal Tech

CO2 Injection

From Hornung, H.G., Adam, P.H., Germain, P., Fujii, K., Rasheed, A., “On transition and transition control in hypervelocity flows,” Proceedings of the Ninth Asian Congress of Fluid Mechanics, 2002

CO2 Transition Re* is about 4X that of Air and N2

CO2

Air & N2

CO2

Air

Acoustic Absorption

2nd Mode Instability (Acoustic)

For CO2 internal energy and acoustic instability modes overlap

Curves for 3 total enthalpy values

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Porous Injector Results (10 MJ/kg): CO2 Delays Transition Zero injectionTransition at

Re = 4.12 x 106

Ar injection at 11.6 g/sec Transition at

Re = 2.88 x 106

Exploring Transition Control Via Energy Transfer to Internal Modes

CO2 injection at 11.6 g/secLaminar Flow past

Re = 5.22 x 106

No

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Tra

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St)

Reynolds Number based on distance from nose tip

Turbulent Heating Correlations

Laminar Heating

Measured Heat TransferTransition Transition

Laminar

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Summary•Hypersonic flight requires advancement of critical scientific disciplines

• Agencies and countries are actively collaborating

• National Hypersonic Foundational Research Plan

• HIFiRE

• NATO RTO working groups

• High-fidelity, large-scale numerical simulations and laser-based diagnostics are changing the game

• Breakthrough science is impacting technology maturation

• Look for the exploitation of rate-dependent energetic processes

Thank You!