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Afterburning Missile Base Flow Modeling and Analyses


OBJECTIVE: To develop a validated, advanced, detailed physics-based capability to accurately model the separated flow physics immediately downstream in the base region of a propulsive supersonic/hypersonic missile. DESCRIPTION: Missile base flow is an area that has eluded a satisfactory solution since the 1950's. This flow region contains most of the complications of aero-thermo-chemical problems including flow separation, two-phase gas/particle non-equilibrium, chemical kinetics, turbulent flow, and complex geometry. Recently, progress has been made on predictions of the basic, blunt-base, cylindrical geometry with state-of-the-art hybrid Reynolds-averaged Navier-Stokes/Large Eddy Simulation (RANS/LES) computational fluid dynamics (CFD) formulations although these predictions are still far from routine, can be computationally expensive and have been restricted to cold flows. While additional strategies might be required to resolve the turbulence in the base flow region, the validation and systematic refinement of models has been hindered by the absence of well-controlled laboratory base flow (pressure and heat transfer) data, augmented by detailed non-intrusive time-resolved flow visualization, diagnostics and in-field measurements under missile-representative hot, afterburning flow conditions. Innovative CFD solutions techniques and benchmark experimental data are sought which can advance the state of the art for the prediction of the flow field in the base region of a supersonic/hypersonic missile flying at low altitude (turbulent flow). This predictive capability, within an existing computational fluid dynamic (CFD) model, must account for the effects of incoming boundary layer, asymmetric body flows, multi-phase effects, the exhaust of fuel rich, high-temperature chemically-reacting gases from the nozzle, vigorous afterburning in the base region and the downstream plume, as well as three-dimensional arbitrary geometry. The model shall be able to predict the flow separation processes, as well as the overall near-wake flow structure and base drag. PHASE I: Innovative technical approaches will be formulated in Phase I leading to an advanced computational fluid dynamic (CFD) model, as a marketable product. These technical approaches must address the key problem areas of supersonic/hypersonic base flow modeling; namely, the coupled effects of incoming boundary layer, asymmetric body flows, the exhaust of high temperature fuel rich reactive gases from the nozzle, vigorous afterburning in the base region and the downstream plume, as well as three-dimensional arbitrary geometry. These formulated approaches shall be coded into an existing computational fluid dynamic model for non-equilibrium, chemically reacting multi-phase flows and preliminary validation shall be demonstrated for afterburning baseflows. These test runs will be documented in the Phase I final report along with a detailed plan for product development under Phase II. PHASE II: The physical model formulated in Phase I will be developed and refined as necessary to produce an advanced physics-based high-fidelity simulation model or CFD code to evaluate base interaction flowfield performance over a range of flight scenarios of interest. Benchmark experimental data will be required for model validation for baseflow interaction flow fields representing systematic variations of flight Mach ranging from ~ 2 to 4. Though not strictly required, any opportunities to acquire such high quality axisymmetric, supersonic experimental base flow measurements under representative high-temperature afterburning exhaust conditions, would be beneficial. As a final product, the advanced CFD code should be fully executable on a linux cluster computer requiring no more than 200 CPUs, 16 GB memory per node, and run times within 24 hours. PHASE III: If successful, the end result of this Phase I/Phase II research effort will be a validated predictive model for the analysis of supersonic/hypersonic, low altitude, missile base flows. The transition of this product (a validated research tool) to an operational capability will require additional upgrades of the software tool set for a user friendly environment along with the concurrent development of application specific data bases to include the required input parameters such as missile geometries, solid rocket motor properties, and performance parameters. For military applications, this technology is directly applicable to all rocket propulsion missile systems. The most likely customer and source of Government funding for Phase III will be those service project offices responsible for the development of advanced missile systems such as the SM-3, THAAD, and PAC-3 programs. For commercial applications, this technology is directly applicable to all commercial launch systems such as the NASA Aries, and the Delta and Atlas families. REFERENCES: 1. Walker, B.J. and Petrie, H.L.,"Tactical Missile Base flow Investigation,"JANNAF 15th Exhaust Plume Technology Meeting, May 1985. 2. Tucker, K. P. and Shyy, W.,"A Numerical Analysis of Supersonic Flow Over an Axisymmetric Afterbody,"AIAA 29th Joint Propulsion Conference and Exhibit, June 28-30, 1993. 3. Sahu, J.,"Numerical Computations of Supersonic Base Flow with Special Emphasis on Turbulence Modeling,"AIAA Journal, 32(7), pp. 1547-1549, 1994. 4. Herrin, J. L. and J. C. Dutton,"Supersonic Base Flow Experiments in the Near-Wake of a Cylindrical Afterbody,"AIAA Journal, 32:1, 77-83, Jan. 1994. 5. Simmons, F.S., Rocket Exhaust Plume Phenomenology, ISBN 1 884989 08 X, AIAA, 2000. 6. Forsythe, J. R., Hoffmann, K. A., Cummings, R. M., Squires, K. D.,"Detached Eddy Simulation With Compressibility Corrections Applied to a Supersonic Axisymmetric Base Flow,"Journal of Fluids Engineering, v. 124, pp. 911-923, December 2002. 7. P. M. Danehy, S. O'Byrne, A. D. Cutler, and C. G. Rodriguez,"Coherent Anti-Stokes Raman Scattering (CARS) as a Probe for Supersonic Hydrogen-Fuel/Air Mixing,"JANNAF APS/CS/PSHS/MSS Joint Meeting, Colorado Springs, CO, Dec. 1-5, 2003. 8. S. O'Byrne, P. M. Danehy, A. D. Cutler,"Dual-Pump CARS Thermometry and Species Concentration Measurements in a Supersonic Combustor,"AIAA-2004-0710, 42nd Aerosciences Mtg, Reno, Jan 5-8, 2004. 9. Kastengren, A. and Dutton, J.C.,"Wake Topology in a Three-Dimensional Supersonic Base Flow,"AIAA-2004-2340, 34th AIAA Fluid Dynamics Conference and Exhibit, Portland, Oregon, June 28-1, 2004. 10. Kawai, S.,"Computational Study of a Supersonic Base Flow Using Hybrid Turbulence Methodology,"AIAA Journal, 3(6):1265-1275 (2005). 10. Kennedy, K.D, Mikkelsen, C.D., and B. J. Walker, B.J.,"Missile Base Flow: Hybrid RANS/LES Computational Fluid Dynamics Comparisons to Measurements; Part II,"JANNAF 31st Exhaust Plume and Signatures Subcommittee Meeting, Dayton, OH, October 2009.
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