AFRL-AFOSR-VA-TR-2017-0054 Energy Transformation, Transfer, and Release Dynamics in High-Speed Turbulent Flows

Delay length for chemical-reaction initiation downstream of jet-injection was attributed to turbulent mixing and not chemicalkinetics, for flows investigated. Inclined-jet injection dramatically decreases freestream-flow disturbances, relative to normal-jet injection, but increases ignition distance. This penalty may be acceptable considering the lower total-pressure losses thanfor normal injection. New experimental techniques developed allowed non-intrusive measurement of convecting velocityfields in supersonic flows and used for validation of LES of jet-injection flow in a supersonic stream. Small-scale experimentsrevealed 3D behavior of scalar mixing. In DNS, the turbulent fluid-mixing behavior of fluids with variable density revealed newscaling, providing guidance for subgrid-scale (SGS) modeling of variable-density flows. A new SGS combustion model (EVM)was developed for distributed-reaction zone (DRZ) environments allowing efficient computation of turbulent combustion,extending to hydrocarbon combustion. Integrated in a LES of turbulent combustion of a hydrogen jet in supersonic airDISTRIBUTION A: Distribution approved for public release. crossflow it captured many important flow features. Unphysical scalar excursions in finite-difference LES modeling weretraced to dispersion errors of finite-difference operators. Many presentations, conference papers, and publications derivedfrom this effort, as listed and discussed in the report. Distribution StatementThis is block 12 on the SF298 form.Distribution A Approved for Public Release Explanation for Distribution StatementIf this is not approved for public release, please provide a short explanation. E.g., contains proprietary information. SF298 FormPlease attach your SF298 form. A blank SF298 can be found here. Please do not password protect or secure the PDF The maximum file sizefor an SF298 is 50MB.AFOSR_FA9550-12-1-0461_Final_sf298_20170301b_1.pdf Upload the Report Document. File must be a PDF. Please do not password protect or secure the PDF . The maximum filesize for the Report Document is 50MB.AFOSR_FA9550-12-1-0461_Final_20170301b.pdf Upload a Report Document, if any. The maximum file size for the Report Document is 50MB. Archival Publications (published) during reporting period:Candler, G.V., N. Cymbalist, and P. Dimotakis 2015 Large-Eddy Simulation of Autoignition-Dominated SupersonicCombustion. AIAA-2015-3340. Candler, G.V., N. Cymbalist, and P. Dimotakis 2017 Wall-Modeled Large-Eddy Simulation of Autoignition-DominatedSupersonic Combustion. AIAA J. (to appear). Cymbalist, N., 2016 Mixing, chemical reactions, and combustion in supersonic flows. Ph.D. thesis, California Institute ofTechnology. Cymbalist, N., G.V. Candler, and P.E. Dimotakis 2016 Application of the Evolution-Variable Manifold Approach to Cavity-Stabilized Ethylene Combustion. AIAA Paper 2016-3481. Cymbalist, N., and P.E. Dimotakis 2015 On Autoignition-Dominated Supersonic Combustion," AIAA Paper 2015-2315. Ferrero, P., A. Kartha, P.K. Subbareddy, G.V. Candler, and P.E. Dimotakis 2013 LES of a High-Reynolds Number, ChemicallyReacting Mixing Layer. AIAA Paper 2013-3185.Gat, I., G. Matheou, D. Chung, and P. Dimotakis 2016 Acceleration-driven variable-density turbulent flow. In proceedings,VIIIth Int. Symp. on Stratified Flows (San Diego, USA, 29 Aug. 1 Sept. 2016). GS, Sidharth, A. Kartha and G.V. Candler 2016 Filtered Velocity Based LES of Mixing in High Speed Recirculating ShearFlow. AIAA Paper 2016-3184. GS, Sidharth, and G.V. Candler 2015 Stretched-Vortex Based Subgrid-Scale Modeling of Variable-Density Flows. AIAA Paper2015-2782. GS, Sidharth, G.V. Candler, and P.E. Dimotakis 2014 Subgrid-Scale Modeling of Baroclinic Vorticity. AIAA Paper 2014-3214. Kartha, A., P.K. Subbareddy, G.V. Candler, and P.E. Dimotakis 2014 Large-Eddy Simulation of Supersonic Reacting MixingLayers. AIAA Paper 2014-3030. DISTRIBUTION A: Distribution approved for public release. Kartha, A., P. Subbareddy, G.V. Candler, and P. Dimotakis 2015 LES of Reacting Mixing Layers: Influence of InflowConditions and Heat Release. AIAA Paper 2015-3207. Matheou, G., and P. Dimotakis 2014 Scalar excursions in large-eddy simulations. 7th AIAA Theoretical Fluid MechanicsConference (AIAA Aviation and Aeronautics Forum and Exposition, June 2014, Atlanta, GA), AIAA Paper 2014-3209. Matheou, G., and P.E. Dimotakis 2016 Scalar excursions in large-eddy simulations. Journal of Computational Physics 327:97-120. Subbareddy, P.K., G.V. Candler, and P. Ferrero 2014 Scalar Conservation in Large Eddy Simulations of Reacting Flows. AIAAPaper 2014-3203.New discoveries, inventions, or patent disclosures: Do you have any discoveries, inventions, or patent disclosures to report for this period?No Please describe and include any notable dates Do you plan to pursue a claim for personal or organizational intellectual property? Changes in research objectives (if any):None Change in AFOSR Program Officer, if any:None Extensions granted or milestones slipped, if any:One-year no-cost extension