Aerothermodynamics &                                                                                              Turbulen...
Pizza, Skeet Shooting                                                                                                  and...
AFRL Pizza                                                       15 Minutes or Less                                       ...
Aerothermodynamics & Turbulence                     Energy Dynamics in High-Speed Flows    The Environment Around a High-S...
2012 AFOSR SPRING REVIEW            2307/A Aerothermodynamics and TurbulenceNAME: John D. Schmisseur                      ...
Outline• Scientific Challenges• The Big Picture                                                                Leading the...
Scientific Challenges in                         AerothermodynamicsThe intersection of shock waves,                       ...
A The Challenging EnvironmentHigh-Speed FlightEnvironments Cannot BeDuplicated in GroundFacilities                        ...
Unprecedented OpportunitiesLarge-Scale Computing and                                                                      ...
Perspective from Reentry Altitudes                                          HTV-2Marquee                                  ...
Transitioning Science:            New Testing CapabilitiesIntegrated Computations and Experiments                         ...
AFOSR as a Catalyst                                                                                                JTOH Wo...
World-Class Researchers• Members of the NAE (6)                                                                           ...
What Skeet Shooting Has Taught Me About Program Management                                                                ...
Notable Past Highlights                                                                                   Malmuth and Horn...
Extending the Vision of Aerothermodynamics               & Turbulence                                                     ...
Outline• Scientific Challenges• The Big Picture• Portfolio Management• Evolving Research  Directions                      ...
Kinetic Energy Transfer in Turbulent FlowsHow does the flow of energybetween the turbulent spectrumand other flow structur...
Kinetic Energy Transfer in Turbulent FlowsJet CrackleAn intense form of acoustic radiation• Distinguishing feature of soun...
Kinetic Energy Transfer in Turbulent FlowsLong-Range Propagation ofCrackle WavesWe now have a DNS     model source:Identif...
Kinetic Energy Transfer in Turbulent Flows     High frequency actuation reduces near field     jet sound by inhibiting coh...
Kinetic Energy Transfer in Turbulent Flows                                                                                ...
Kinetic Energy Transfer in Turbulent Flows  FLEET – Femtosecond Laser Electronic Excitation Tagging Provides New Insight I...
Kinetic Energy Transfer in Turbulent FlowsParadigm Change in Fluid-Thermal-StructuralInteraction Modeling                 ...
Kinetic Energy Transfer in Turbulent Flows   Lighter, More Compliant Surface Panels May Actually Reduce                   ...
Intermodal Energy Transfer in Laminar Flows  Direct Numerical Simulation of  Vibrationally Active Gas Flows  • Vibrational...
Intermodal Energy Transfer in Laminar FlowsStability analysis reveals                                                     ...
Understanding Nonequlibrium Energy Transfer                      In High-Enthalpy Flows For high-enthalpy flows energy    ...
Understanding Nonequlibrium Energy Transfer                          In High-Temperature FlowsDissecting the Anatomy of Sh...
Understanding Nonequlibrium Energy Transfer                        In High-Temperature Flows                              ...
Understanding Nonequlibrium Energy Transfer                      In High-Temperature FlowsPure Molecular Dynamics Simulati...
Understanding Nonequlibrium Energy Transfer               In High-Temperature Flows    Translational nonequilbrium     stu...
Understanding Nonequlibrium Energy TransferIn High-Temperature Flows New High-Fidelity Modeling of Subsonic Plasma Flow Fa...
MURI: Fundamental Processes in High-Temperature                          Hypersonic Flows               Graham V. Candler,...
Understanding Nonequlibrium Energy Transfer                                               In High-Temperature Flows       ...
Outline• Motivation                                             • AFRL Pizza - high-speed systems                         ...
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Schmisseur - Aerothermodynamics and Turbulence - Spring Review 2012

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Dr. John Schmisseur presents an overview of his program - Aerothermodynamics and Turbulence - at the AFOSR 2012 Spring Review.

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Schmisseur - Aerothermodynamics and Turbulence - Spring Review 2012

  1. 1. Aerothermodynamics & Turbulence 08 MAR 2012 John D. Schmisseur Program Manager AFOSR/RSA Integrity  Service  Excellence Air Force Research Laboratory15 February 2012 DISTRIBUTION A: Approved for public release; distribution is unlimited. 1
  2. 2. Pizza, Skeet Shooting and the Future of Aerothermodynamics 09 MAR 2012 John D. Schmisseur Program Manager AFOSR/RSA Integrity  Service  Excellence Air Force Research Laboratory15 February 2012 DISTRIBUTION A: Approved for public release; distribution is unlimited. 2
  3. 3. AFRL Pizza 15 Minutes or Less Delivery at 500 nm/hrDelivery at Mach 6~50 X increase incoverage DISTRIBUTION A: Approved for public release; distribution is unlimited. 3
  4. 4. Aerothermodynamics & Turbulence Energy Dynamics in High-Speed Flows The Environment Around a High-Speed Vehicle is Dominated by Rate-Dependent Energetic Processes Laminar-Turbulent Transition: A “Race” Between Competing InstabilitiesShock-Excited FlowStates and Gas-Surface Interactionsare Driven byReaction Rates Turbulent and Shock- Interaction Heat Transfer: Transfer of kinetic to thermal energy poorly understood DISTRIBUTION A: Approved for public release; distribution is unlimited. 4
  5. 5. 2012 AFOSR SPRING REVIEW 2307/A Aerothermodynamics and TurbulenceNAME: John D. Schmisseur PartnersAerothermodynamics &TurbulenceBRIEF DESCRIPTION OF PORTFOLIO: National Hypersonic Joint Technology Foundational Research Office -Identify, Model and Exploit critical Plan Hypersonicsphysical phenomena in turbulent andhigh-speed flows• emphasis on energy transferSole DoD basic research program in this area Assessment of SOA and Future ResearchSUB-AREAS IN PORTFOLIO: Directions • Boundary Layer Physics Jet Noise • Shock-Dominated Flows • Gas Thermophysics Arnold • Gas-Surface Interactions Engineering Tech Development Transition • Turbulence and Transition Center DISTRIBUTION A: Approved for public release; distribution is unlimited. 5
  6. 6. Outline• Scientific Challenges• The Big Picture Leading the International• Portfolio Management Research Community• Evolving Research Identifying and Responding to New Directions Opportunities• Research Highlights DISTRIBUTION A: Approved for public release; distribution is unlimited. 6
  7. 7. Scientific Challenges in AerothermodynamicsThe intersection of shock waves, M=10, Re = 2 Millionturbulence, thermophysics and Temperature Gradientchemistry Bartkowicz/Candler U Minn hn Rate-Dependent Energy Transfer Processes are Critical – yet poorly understood Vibrational Rotational Electronic Reactions DISTRIBUTION A: Approved for public release; distribution is unlimited. 7
  8. 8. A The Challenging EnvironmentHigh-Speed FlightEnvironments Cannot BeDuplicated in GroundFacilities CUBRC LENS Shock Tunnel•Test gas velocity of 10,000 mph • Half of orbital velocity!• Few hundred millionths of a U. Illinois second test time Expansion Tube• Measure chemical species DISTRIBUTION A: Approved for public release; distribution is unlimited. 8
  9. 9. Unprecedented OpportunitiesLarge-Scale Computing and There is No Mature IndustryOptical Diagnostics Provide Base for Hypersonic SystemsIncredible Insight into Critical • Opportunity to rapidly transitionMicroscale Phenomena science breakthroughs for integration into emerging systems! Model-Free Spectroscopic Sim. of Measurement of Noise Transient Material Generation Fletcher and Chazot, VKI Response in Jet O N Si O N O Si O C O O O C O O O O Si O O C Molecular O N O N N N O N N Dynamic Sim. N N Si N O C O Si O Si N O Of Gas- O O O O Surface SiO2 SiO2 SiO2 SiO2SiC SiC SiC SiC SiC SiC SiC SiC Interaction DISTRIBUTION A: Approved for public release; distribution is unlimited. 9
  10. 10. Perspective from Reentry Altitudes HTV-2Marquee Rough Estimate – A BillionHypersonics X-51 Dollar Total NationalDemos and Investment AHW*Systems DoD Joint Technology Office on Hypersonics - JTOH ~ $20 MFoundational • AFRL, NASA, Sandia In current FYResearch • AFOSR is only DoDBA 1 and for BA1 investment in basicearly BA 2 science National Hypersonic Foundational Research Plan – AFOSR Led, Adopted by JTOHFoundational NHSC InternationalResearch HARP Collaboration • Aerothermo Coord. of MajorEfforts • Propulsion Academic Centers DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution • Materials
  11. 11. Transitioning Science: New Testing CapabilitiesIntegrated Computations and Experiments Focused schlieren image of BL Falcon HTV-2predict and verify instabilities and assess the transition obtained on 7° transitionsurface thermal load… cone at Mach 10, Re/L = 2.0×106/ft Schneider, Purdue Candler … resulting in an unprecedented U. Minn. capability for the test and analysis of high-speed systems Breakthrough method for Low-Frequency Acoustic Pitot Probe High-Frequency Temperatur Acoustic Pitot Probe instability measurement e Sensitive Paint Primar High-Fidelity y Test Article Auxiliary Model Numerical Support Hemisphere Purdue /Sandia Methods yield Heat-Transfer Probe Transition Cone detailed insight into physics Temperature-Sensitive Paint provides global heating AEDC Tunnel 9 DISTRIBUTION A: Approved for public release; distribution is unlimited. 11
  12. 12. AFOSR as a Catalyst JTOH Workshop NASA Environmentally Emerging Capabilities for the Responsible Aerospace (ERA) Design and Analysis of High- program seeks new efficient Speed/ Hypersonic Systems March 27-28, 2012 transport designs Arlington, VA Surprising Designs for Eco-friendly Airliner Guy Norris Jan 13, 2012 AIAA HyTASP PCTargets• 42dB noise reduction from stage 4 std Dialog on the opportunities• 50% fuel burn reduction from 1998 std and challenges for transition“…would potentially involve partnerships of maturing scientificwith the U.S. Air Force and industry.” capabilities to engineeringAMC-NASA connections result from practiceAFOSR Workshops July and Dec 2010 DISTRIBUTION A: Approved for public release; distribution is unlimited..
  13. 13. World-Class Researchers• Members of the NAE (6) Accomplishments• NSSEFF Fellow• DoD Advisory Boards • Dream Team of world-class • AF SAB Principal Investigators• JASON• Def. Studies Group • Strong Connections to the• AIAA Fellows (11) 12 Applied Research and Test• PECASE (2) Community• NSF CAREER (4)• OSR Young Investigator (4) • Research Breakthroughs are• AIAA Past President (2) being transitioned and• AIAA Awards guiding technology• Thermophysics Award (2) maturation programs• Fluid Dynamics Award (4)• Ground Test Award • Portfolio is leading the• Aero. Measurement Tech.• Plasmadynamics and Lasers international research• Atwood Educator Award community in• APS Frenkiel Award (2) aerothermodynamics• AF Chief Scientists (2)• Prior PM: Dr. S. Walker DISTRIBUTION A: Approved for public release; distribution is unlimited. 13
  14. 14. What Skeet Shooting Has Taught Me About Program Management • Keep your eyes open • Know which way the wind is blowing • Be ready • Start and stay in front of the target • How you think about the target effects your approach (and ability to hit it!) DISTRIBUTION A: Approved for public release; distribution is unlimited. 14
  15. 15. Notable Past Highlights Malmuth and Hornung - Energy transfer at the micro- Transition Control via acoustic absorptive surface and molecular scalesSurface - Turbulent Solid drives the macroscopic flowCandler and Martin - Turbulence Dampening behaviorThrough Endothermic Reactions Porous Surface - Laminar Saric – Crossflow transition delayed Imagine if we could internal energy and acoustic by promoting For CO control 2 growth of more instability modes overlap the transfer of energy for 3 total enthalpy values stable instabilities Curves within the various states (kinetic, Acoustic Absorption thermodynamic, internal and CO2 chemical) ….. Leyva and Shepherd – 2nd Mode Transition delay via Air Instability internal energy absorption (Acoustic) DISTRIBUTION A: Approved for public release; distribution is unlimited. 15
  16. 16. Extending the Vision of Aerothermodynamics & Turbulence Key: PI corp must start Aerodynamics- considering and Focus on Energy Driven Focus communicating their work Boundary Transfer Mechanisms within this context Layers, Shock in Fluids Interactions, Other Aerothermo- dynamics Portfolios Thermal Management, Energy Storage and Transport, Natural Opportunities Plasma Phen. for cross-discipline Atmospheric collaboration Energy - MURI, BRI Propagation, Fluid Phen. In Gas Lasers, Laser-Material Interactions(?) DISTRIBUTION A: Approved for public release; distribution is unlimited. 16
  17. 17. Outline• Scientific Challenges• The Big Picture• Portfolio Management• Evolving Research Directions Presented in terms of new• Research Highlights portfolio emphasis: energy transfer mechanisms DISTRIBUTION A: Approved for public release; distribution is unlimited. 17
  18. 18. Kinetic Energy Transfer in Turbulent FlowsHow does the flow of energybetween the turbulent spectrumand other flow structures shapemacroscopic flow dynamics? CharLES code simulations of supersonicModeling Turbulent Flows rectangular jet - P. Moin, Stanford Resolved Modeled Energy Ma = 2.3 Req = 5000 Turbulent Energy Kolmogorov Scale Spectrum ~ h-1 ~ d-1 WavenumberRANS LES DNS Large-Eddy Simulation of Compression Eng. First Corner Shock/Boundary Layer Interaction – J. Poggie, AFRL/RB Tool Increasing Fidelity and Cost Principles DISTRIBUTION A: Approved for public release; distribution is unlimited. 18
  19. 19. Kinetic Energy Transfer in Turbulent FlowsJet CrackleAn intense form of acoustic radiation• Distinguishing feature of sound on military platforms - fighters and rockets• Mechanisms are unclear, particularly Prof. Jonathan source of its peculiar signature Freund Kritzer Faculty• Direct numerical simulation Scholar • Mechanical (no turbulence model) Science & integrated with nonlinear Engineering and propagation theory explores Aerospace root mechanisms of jet crackle Engineering • Fellow American• Model simulations have for Physical Society the first time reproduced • APS/DFD Frenkiel crackle --- a key step toward Award (2008) understanding and reducing • Associate Fellow DISTRIBUTION A: Approved for public release; distribution is unlimited. AIAA 19
  20. 20. Kinetic Energy Transfer in Turbulent FlowsLong-Range Propagation ofCrackle WavesWe now have a DNS model source:Identified key factor: how the Mach wavestransition from conical to spherical behaviorSpherical decay is much faster- stronglyaffects the mid- and long-range peakamplitudesLength of conical portion depends ondynamics of large turbulent eddies in the jet DISTRIBUTION A: Approved for public release; distribution is unlimited. 20
  21. 21. Kinetic Energy Transfer in Turbulent Flows High frequency actuation reduces near field jet sound by inhibiting coherent structures Synergy between CFD and experiment pays off • Experiments reveal small Prof. M. Samimy high-frequency actuation can Nordholt Professor reduce jet noise • Fellow AIAA, APS, AAAS, • But how do high-frequency ASME techniques actually affect the structures that generate noise? • This research suggests that the signals inhibit the growth of coherent structures in the near field, which in turn affects Prof. D. Gaitonde the far field noise Glenn Professor • Fellow AIAA,Gaitonde and Samimy, Phys. Fluids,A: Approved No. 9, 2011 distribution is unlimited. DISTRIBUTION Vol. 23, for public release; AFRL 21
  22. 22. Kinetic Energy Transfer in Turbulent Flows Experiments and simulations coordinated as never before to enhance understanding Three dimensionality of structures of various scales influences wave generation and propagation Near field provides best opportunity to implement feedback control Impact of actuation: higher-frequency excitation disrupts formation and evolution of larger-scale structures Human HearingGaitonde, AIAA Paper 2011-23, 2011. DISTRIBUTION A: Approved for public release; distribution is unlimited. 22
  23. 23. Kinetic Energy Transfer in Turbulent Flows FLEET – Femtosecond Laser Electronic Excitation Tagging Provides New Insight Into Turbulent Flows • FLEET excites and tracks selected N2 Lines are written by molecules the laser and imaged • Spatial resolution – tens of microns to 1m with a fast gated • Temporal resolution - tenths of a camera. microsecond • Temperature range from condensation to Dr. Richard B. greater than 2000K. Miles Robert Porter Patterson Professor of Mechanical and Aerospace Engineering • Member of the 750 National Academy 600 of Engineering Velocity (m/s) 450 300 • Fellow of the AIAA 150 and the OAS • 2001 recipient of 0 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 Spectrum of FLEET emission in air. Spectral lines X/D 1 2 3 4 5 are associated with the nitrogen First Positive system Height X (cm) the AIAA FLEET measurements of the centerline Aerodynamic velocity in a supersonic jet Measurement• Ref: J. Michael, M. R. Edwards, A. Dogariu, and R. B.Miles, “Femtosecond laser electronic excitation tagging Technology Awardfor quantitative velocity imaging in air,” Appl. Opt. 50,5158 (2011) DISTRIBUTION A: Approved for public release; distribution is unlimited. 23
  24. 24. Kinetic Energy Transfer in Turbulent FlowsParadigm Change in Fluid-Thermal-StructuralInteraction Modeling Coupling of fluid, structural analysis reveals interactions unseen in prior uncoupled Dr. Jack approaches McNamara Assistant Professor Integrated analysis • Mechanical & reveals change in Aerospace Engineering surface heating due • Senior to structure-driven Member AIAA shock motion • 2011 Recipient Stationary location of AFOSR YIP of shock in Award uncoupled approach1Crowell, Miller, McNamara, “Computational Modeling for Conjugate Heat Transfer ofShock-Surface Interactions on Compliant Skin Panels,” AIAA-2011-2017, 2011. DISTRIBUTION A: Approved for public release; distribution is unlimited. 24
  25. 25. Kinetic Energy Transfer in Turbulent Flows Lighter, More Compliant Surface Panels May Actually Reduce Aerodynamic Heating First of a kind studies reveal a new strategy for simultaneously mitigating vehicle weight and aerodynamic heating • Series of thermally buckled panels predicted to delay transition • Does change in boundary layer base state disrupt instability growth (?)22Riley, Z., McNamara, J., and Johnson, H., “Hypersonic Boundary Layer Stability in the Presence of Thermo-StructuralCompliance,” 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, April 2012.
  26. 26. Intermodal Energy Transfer in Laminar Flows Direct Numerical Simulation of Vibrationally Active Gas Flows • Vibrational energy absorption can attenuate acoustic disturbances – delaying laminar-turbulent transition • Simulations provide a physics-based understanding of how and why this occurs to enable novel flow control strategies Dr. Candler McKnight Acoustic Wave Temperature Fluctuation (K) Vibrational Energy Presidential Damping per Wavelength Professor • Fellow of AIAA • 2009 NSSEFF • 2007 AIAA Thermophysics Award CO2 T = 3000KDamping is caused by the Frequencyinteraction of the acoustic wave withthe relaxation qualities of a molecule Simulations allow isolation of effects of vibrational absorption and chemistry onWagnild & Candler, AIAA 2012-922 for public release; distribution is unlimited. attenuation DISTRIBUTION A: Approved instability 26
  27. 27. Intermodal Energy Transfer in Laminar FlowsStability analysis reveals N = ln (A/A0)contributions of specificvibrational modes toinstability attenuation• Bending modecontributes most todisturbance damping• Contribution increaseswith larger Cvv Percent change in N factor Simulation of Mach 6 flow over a cone with Imposed acoustic wave with largest versus distance along the cone damping rate DISTRIBUTION A: Approved for public release; distribution is unlimited. 27
  28. 28. Understanding Nonequlibrium Energy Transfer In High-Enthalpy Flows For high-enthalpy flows energy hn transfer between the flow, thermodynamic and chemical Vibrational Rotational Electronic Reactions processes becomes significantPredictions Fail as Increasing Internal Energy ExperimentChemical Numerical Simulation 80 Experiment Air, 4.5 Mj/kg Air, 10.4 Mj/kg Air, 15.2 Mj/kgComplexity 70 Nitrogen 1024 x 512 simulation Heat Transfer Rate (Watt/cm2) 60Increases 50Candler, U. Minn 40NSSEFF, CII 30 20 10 0 0 4 8 12 16 x (cm) Excited States Impact Ex: Catalytic Heating Surface reactions will Expansion Macroscopic Behavior be driven by available O O2 Tunnel CO2 at 5 MJ/kg freestream species in O Shock enthalpy: nonequilibrium Tunnel - Shock Tunnel excites internal O O modes environment - Expansion Tunnel does not M. MacLean and M. Holden, CUBRC HEATGoal: Characterize, Model and Exploit Nonequilibrium Processes 28 DISTRIBUTION A: Approved for public release; distribution is unlimited.
  29. 29. Understanding Nonequlibrium Energy Transfer In High-Temperature FlowsDissecting the Anatomy of Shock-BoundaryLayer Interaction in Hypervelocity Flow Goal: “Tune” the thermochemical activity to identify critical transitions between perfect and real gas flows. Made possible by novel facility built at Illinois under AFOSR support. Joanna M AustinHypervelocity Expansion Tube •AFOSR Young Investigator Mach 5, Program Award 4 MJ/kg, Air •NSF CAREER Award N2 Mach 7.1 N2 Air •Associate Fellow, Air 2MJ/kg AIAA •AIAA Fluid Dynamics Best 8 MJ/kg Paper Award •Xerox Award for•Current dataset chosen for simulation by NATO RTO AVT 205 group. Faculty Research Swantek and Austin, Int. Shock Wave Symp., July 2011 ExcellenceSwantek and Austin, AIAA ASM Meeting,public release; distribution is unlimited. DISTRIBUTION A: Approved for Jan. 2012 29
  30. 30. Understanding Nonequlibrium Energy Transfer In High-Temperature Flows Transition cross section as a function of Optimization approach enables rotational and vibrational energy – H2 computation of high- temperature chemistry rates for all relevant processes based on reduced number of evaluations1 Quasi-Classical Trajectory method Iain D. Boyd employed to compute cross sections James E. Knott that are integrated to find the rates Chair of (red dots) - 1800 collision states Engineering • Fellow of Am. Inst. Kriging approach used generate cross Aero. Astro. (AIAA) section surface representing 60,000 • 1998 AIAA collision states Lawrence Sperry Award Computed relaxation rates agree well • 2011 AIAA with measured data Thermophysics • Reveal convergence of rates at high Best Paper Award temperatures – contrary to conventional • AFSAB member view1Kim & Boyd, AIAA Paper Approved for public release;January 2012 DISTRIBUTION A: 2012-0362, distribution is unlimited. 30
  31. 31. Understanding Nonequlibrium Energy Transfer In High-Temperature FlowsPure Molecular Dynamics Simulation ofShock Waves Is Now PossibleNew tool to study internal energy transfer in hypersonic flows• No equation of state, transport models, or rate models required• Inter-atomic forces provided by computational chemists are the Dr.sole model, directly linking chemistry and aero communities Schwartzentruber• Dominant internal energy transfer mechanisms can be analyzed Assistantand reduced models formed Professor• Enabled by large-scalecomputing1 and a novel • 2011 Visitingnumerical method2 Professor, von Karman Institute1Valentini • AFOSR Young and Schwartzentruber, InvestigatorPhysics of Fluids, 21 (2009) Award (2009)2Valentiniand Schwartzentruber, • 2007 AIAAJournal of Computational Physics, Orville andVol. 228, No. 23 (2009) Wilbur Wright DISTRIBUTION A: Approved for public release; distribution is unlimited. Award 31
  32. 32. Understanding Nonequlibrium Energy Transfer In High-Temperature Flows Translational nonequilbrium study (viscosity and massdiffusion) complete and validated with experiment.• Species separation in an Argon-HeliumMixture shock wave vs. experiment Rotational nonequilbrium study reveals new insights. Rotational de-excitation (Trot>Ttr) is slowRotational Rotational excitation Zrotexcitation (Trot<Ttr) is fastin a N2shock vs. Current model:experiment Zrot=const or Zrot=f(Ttr) New model: Zrot=f(Ttr and Trot)??Vibrational excitation and dissociation study underway. DISTRIBUTION A: Approved for public release; distribution is unlimited. 32
  33. 33. Understanding Nonequlibrium Energy TransferIn High-Temperature Flows New High-Fidelity Modeling of Subsonic Plasma Flow Facilities Integrated Experimental-Numerical Collaboration US3D confirms plasma jet to be in Local • Boundary layer in subsonic Thermo. Equil. (LTE), however, boundary plasmatron flow requires modeling to layer is highly nonequilibrium. extrapolate to hypersonic conditions • Current modeling valid only for stagnation line heat flux • Combine Minnesota’s leading-edge modeling capabilities with high-quality data from VKI’s Plasmatron Experimental images of passive to active oxidation of a UHTC sample • This effort could drive a new level of understanding and form new predictive models for gas-surface reactions for real TPS No current modeling capability. DISTRIBUTION A: Approved for public release; distribution is unlimited. 33
  34. 34. MURI: Fundamental Processes in High-Temperature Hypersonic Flows Graham V. Candler, Don Truhlar, Adri van Duin, Tim Minton, Deborah Levin Tom Schwartzentruber, Erica Corral, Dan Kelley and Paul DesJardinMURI Explores Molecular scale Molecular Dynamics Reaction Dynamics ExperimentsKinetic Processes to AdvanceSimulation of Vehicle ScalePhenomenaIntegration of Aerothermodynamics,Chemistry and Materials Research todevelop advanced models for gas-surfaceinteractions Approach• Use detailed quantum mechanics to develop accurate force fields for key processes• Train reactive force field for MD simulations Reactive of post-shock wave flows and gas-surface Material Surface Effects Force Fields interactions• Extend to continuum models with DSMC models and state-specific simulations High-Fidelity,• Perform experiments at all scales to provide Large-Scale validation data for model generation CFD University DISTRIBUTION A: Approved for public release; distribution is unlimited. of Minnesota, Penn State University, Montana State University, University of Arizona, and University of Buffalo 34
  35. 35. Understanding Nonequlibrium Energy Transfer In High-Temperature Flows Novel Measurements of Carbon Oxidation Rates Under Controlled Conditions Carbon ablation models rely on oxidation rate data; previous measurements were obtained under poorly controlled conditions, making it difficult to interpret the data. The rves for carbon materials using “conventional” When comparing oxidation rates for HOPG and C-C as a University ofshow differences in weightmetric analysis (TGA) Arizona team has developed a new approach1600°C we observe very similar rates at function of PO2 at to loss reduce these uncertainties and provide accurate high pressures and a deviation at low pressures as a function of temperature data. ,L /J H /$#( @$*+#,$% J -,03& -& Conventional” Carbon Oxidation /"0>+0O"0$% 7&9 N $O"0& #>+-&"#& "0& &EP vs. New Test 4 [ 2;EP 7& PO2 Carbon 9 RP & & ;! & & $O"0& "N,L #$*+-&"#& Oxidation H M 1 ! /"@5"-,*+&& 100 1600 °C •& ,3F& +0-,*G& & 90 Dr. Erica "NG3+0&"HM9 RP & & % M L ,@,*-& Corral, 5+0+*#$O"0& Loss Rate (Log(g/cm )s )& HOPG -10& 80 Assistant Prof., -4 2& 70 Carbon Black Univ. •of/*J #+& C& ;! &/"@5% & %Arizona 7*& & & -*#J "? R9 *F+& "H! /F$03+-& +N& • AFOSR YIP,I +#& Mass (%) 60 F"? & "N,L *F+& ,0*+#$/*-& 50 Graphene Carbon Fibers • NSF CAREER ? ,*F& /$#( "0& *F+& -G-*+@-& & 40 C-C C-C • Member of+>,$O"0& •& #$*+& AFOSR EF+& L @$G& 30 Graphite -5 HOPG MURI team V%+#& & ( +& J +& 5#+H L *"& +#+0O$% $c $/U& & "H*F+& % 5F$-+& 20 ,0& ! ;! & *F+& /"@5"-,*+& #$*F+#&*F$0& 3#$5F,*+& *F+& 10 V( +#-& SWNT 2 3 4 5 0 PO (Log Pa) 200 400 600 800 1000 1200 1400 2 Temp. (°C) ! "##$% $( & & Oxidation rate data 789+/+@( < : AB&+>,+? & is ONLY possible" H& at. : 1600 °C ;) =: & EF+& 0,>+#-,*G& 7# < ) $*+#,$% . /,+0/+& & -& 1 203,0++#,03& +5*6 4 4 & +#& CDAA& EJ /-"0B7K& & 7 89 . : ;) < : =: +>,+? & & EF+& 0,>+#-,*G& & #,I "0$& < "H7+#,03& Conventional Approach: 4 +5*6& 4 +/+@( +#& & ABCDAA& EJNDE-TGA Approach: Pre- /-" 0B7 K& & using the new test method and will be used for Large variation in rate data; T heat sample under inert gas; gas-surface interaction models; less variation changes during measurement Approved for public release; distribution is unlimited. with form of carbon. take data at constant T DISTRIBUTION A: 35
  36. 36. Outline• Motivation • AFRL Pizza - high-speed systems provide efficient coverage• Scientific Challenges • Intersection of thermophysics, turbulence and chemistry• The Big Picture • Portfolio plays a leading role in international research• Portfolio Management • Lessons from Skeet Shooting: New approach may increase “hits”• Evolving Research • Energy transfer at small scales Directions drives macroscale behavior• Research Highlights • Portfolio PIs are conducting exciting, world-leading research DISTRIBUTION A: Approved for public release; distribution is unlimited. 36

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