RT&L FOCUS AREA(S): Hypersonics TECHNOLOGY AREA(S): Weapons The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: To develop new mathematical constructs and high-fidelity design tools to predict time-accurate electromagnetic signatures of morphing hypersonic vehicles. DESCRIPTION: The Army is interested in designing next-generation hypersonic flight vehicles with enhanced system speed, reach, and lethality addressing Army's and DoD's Priorities in Long Range Precision Fires and Hypersonics. Revolutionary systems must meet new tactical requirements for performance, reach, and lethality, while simultaneously mitigating the strong electromagnetic signatures emitted. New concepts will include the ability of controlling hypersonic vehicle performance and maneuverability based on morphing structures in external and internal aerothermodynamics by time-varying the angle of attack (AOA). The presence of an AOA results in significant differences of the surface temperatures as well as in emissions of electromagnetic characteristics in intensity and spectral band. Historically, computational fluid dynamics has played a central role in the design and development of hypersonic vehicles, largely due to the prohibitive cost associated with testing facilities. However, existing simulation approaches are limited in its ability to predict hypersonic aerothermodynamics and its interactions solving complex fluid, thermal, kinetic, and structural problems using tightly-coupled approaches. Hypersonic modeling under realistic flight conditions is complicated by the nonlinearity and multiphysics nature present that acts across a wide range of scales [1-2]. Variations in atmospheric conditions, chemical kinetics, vibrational excitation, ablation products, and gas-surface interactions further complicate the high enthalpy plasma system [3]. The Army is therefore seeking high-fidelity design approaches to predict the flight environment of a hypersonic vehicle, along with gas-flow chemistry, shock induced heating, and material-response, including thermoacoustics transport, and full-spectrum EM propagation capabilities. Solutions will include novel capabilities for modeling time-varying morphing structures coupled with aerothermochemistry and electromagnetic wave propagation. Electromagnetic frequency ranges of interest include X-band, Ka-band, and also IR/RF. In solving the system of PDEs, the solution must also include accurate physics-based closures for processes including turbulent shear stress and heat transfer fluxes, particle laden flows, and chemical kinetics for any unresolved physics. This research will lead to new solutions to PDEs with faster and greater accuracy. The new tools should be able to handle realistic glide body, missile geometries, and scramjet propulsion systems for sustained powered flight in the Mach 6 to 20 range. Tools must have the ability to be deployed in traditional/emerging high performance computing architectures (CPU GPU) efficiently and demonstrate improved scalability over the state-of-the-art. In-situ visualization and data extraction techniques must be available to provide end users the ability to seamlessly navigate the sea of data encountered in real-time analysis. PHASE I: Develop 3D high-fidelity modeling concepts to predict aero-thermal effects and EM signatures that include both RF/IR signature responses for morphing vehicles and adaptive structures and demonstrate benefits over low fidelity approaches. High fidelity approaches for reacting turbulence and fluid structure interaction should be based on LES and finite rate chemical kinetics. The company should identify strengths/weaknesses associated with alternative solutions, methods, and new concepts. Demonstrate theoretical credibility of proposed computational and include EM experimental validation targets. Computational vetting and demonstration of concepts to be conducted using canonical blunt-nose single or double cone hypersonic shapes and beyond is suitable in this phase. PHASE II: During Phase-II, the framework developed in Phase-I will be extended and validated to support hypersonic morphing vehicles for potential applications in air-breathing missiles, boost-glide missiles, and high-maneuver interceptors with EM signature analysis. Tools should demonstrate ability to model complex aerothermochemistry, thermoacoustics, shock induced heating, structural material response, and broad spectrum EM propagations (e.g., X-band, K-band, IR./RF), using high-fidelity LES approaches. The tools will capture in detail non-equilibrium processes including boundary layer transition to turbulence, onset of material ablation, finite-rate non-equilibrium chemistry, and gas-surface interactions responsible for surface deformation. It shall consider material dielectric properties including RF permittivity, absorptance, reflectance and thermal conductivity. Demonstrate time-accurate predictions based on tightly-coupled fluid structure interaction for time-varying AOA in morphing internal and external hypersonic vehicles. Complete model, executable code, and deploy on state-of-the-art high performance computing systems with demonstrable performance on existing or emerging computing architectures. Demonstrate model validation by comparison with reference DNS databases, EM experimentation in the open literature, or data from the Army or DoD laboratories. The high-fidelity model should demonstrate at least 10% improved accuracy in capturing transients over existing approaches based on RANS or empirical correlations. The complete software package shall be available to ARL during all phases of the project to conduct independent assessment and vetting of the developed tools. Coordinate development efforts with the government, and potential prime-contractor partners, to ensure product relevance and compatibility with missile defense projects and government modeling and simulation systems. The developed complete computational tool sets along with user guide(s) at the end of Phase-II shall be delivered to ARL for government use on HPC platforms to conduct mission projects. PHASE III DUAL USE APPLICATIONS: Collaborate with simulation model developer(s) and/or user(s) on integration of product(s) into a missile defense application. Optimize toolset to accommodate new advances in the technology of tracking and prediction of glide body or cruise missile flight. Transition the technology to an appropriate government or defense contractor for integration and testing. Integrate and validate the functional signature tools into a real-world missile defense application. REFERENCES: Candler, G.V., Rate effects in hypersonic flows , Annual Review of Fluid Mechanics, vol. 51, pp. 379-402, 2019. D'Ambrosio, D., Giordano, D., Electromagnetic Fluid Dynamics for Aerospace Applications , Journal of Thermophysics and Heat Transfer, vol. 21 (2), 2007. Bisek, N. J., Boyd, I.D., Poggie, J., "Numerical Study of Plasma-Assisted Aerodynamic Control for Hypersonic Vehicles", AIAA J. Spacecraft and Rockets, vol. 46 (3), 2009 KEYWORDS: Hypersonics, aerothermochemistry, morphing systems, computational fluid dynamics
