In this effort Falcon Dancer Inc and our partner, Kord Technologies LLC, will apply an aerothermal heating methodology developed for the design and analysis of high-speed systems to operate efficiently within U.S. Navy Hardware-In-the-Loop (HIL) simulation software. We use historically anchored, fast running local correlations to predict aerodynamic heating. The model is currently implemented as MATLAB based tool set which is used to obtain surface heating rates and skin temperatures for hypersonic vehicles. The software calculates three-dimensional stagnation heating rates and temperatures, and two-dimensional stagnation heating rates and temperatures with and without leading-edge sweep. In addition, it calculates lower and upper surface heating rates and temperatures for flat plates, wedges, and cones. Laminar and turbulent heating rates and temperatures can be calculated, with boundary-layer transition controlled as a function of free-stream Reynolds number and free-stream Mach number or a user supplied routine. The code uses time histories of altitude, Mach number, and angle of attack and roll angle along with a MATLAB 1977 standard atmosphere program to obtain the free-stream properties required to make the calculations. To increase accuracy the model is trained using machine learning on authoritative truth data such as high-fidelity CFD predictions, stability analysis, and/or wind tunnel measurements. The model may be efficiently used with 0D and 1D reduced order models or can be tightly coupled to FEM solvers. The highly integrated and robust technical approach used in this effort will support the TRL maturation of TPS systems using new/novel materials. A typical scenario involves model and device fabrication, computational modeling, testing and final TRL assessment. The key guiding philosophy in our approach will be to develop a digital thread/digital twin which incorporates all the informational knowledge gathered in the design and validation of a TPS into a verifiable mathematical model. These models may then be combined with system level analysis tools to verify the TRL of the proposed vehicle design and to support the final TRL maturation in Phase III. We will work closely with the US Navy to develop a software plan to port the methodology to existing HIL Software framework. This design plan will include software System Requirements Review, Preliminary Design Review and Critical Design Review. A detailed plan will be developed for gathering the information needed from new material developments to support HIL testing.
Benefit: As outlined in the 2018 National Defense Strategy (NDS), the United States is aware that our competitive military advantage has been eroding, and the NDS highlights the importance for greater performance and affordability of weapons within the Department of Defense (DoD). Hypersonic weapon systems are a major emphasis. The Pentagons FY2023 budget request for hypersonic research is $4.7 billionup from $3.8 billion in the FY2022 request. The Missile Defense Agency additionally requested $225.5 million for hypersonic defense budget request. The use of the TPS methodology outlined here as part of a broad Digital Engineering strategy outlined is a key enabling process to achieve these goals. The highly integrated and robust technical approach used in this effort will support the TRL maturation of TPS systems using new/novel materials. A typical scenario involves model and device fabrication, computational modeling, testing and final TRL assessment. The key guiding philosophy in our approach will be to develop a digital thread/digital twin which incorporates all the informational knowledge gathered in the design and validation of a TPS into a verifiable mathematical model. These models are used to estimate performance predictions as well as serving as a system surrogate for quantification of the risk associated with uncertainties in inputs. During TRLs of 1-3 initial models are built using engineering estimates, historical data, and low order approximations. Design of experiments Latin hypercube space filling analysis will be used in conjunction with these low-level approximations to build an initial set of digital models. These initial models will be used perform an UQ analysis to test the sensitivity of the design to uncertainty in the inputs and to guide the next step of the analysis. Based on these inputs an optimal set of higher-fidelity FEM based computations can be performed. The models are recalibrated, and spot checked with a handful of additional computations. Next based on the updated model a subscale and sub-component test campaign is performed which serves to validate the model predictions and numerical sensitivities is conducted. Finally, all data available is used further refine the math models. These models may then be combined with system level analysis tools to verify the TRL of the proposed vehicle design and to support the final TRL maturation in Phase III. Not only will the TPS digital threads be useful to reduce cost and cycle time but the resulting high-fidelity digital twins which result from the process be useful as onboard health and performance diagnostics monitors. In addition, their use in the application of Deep Learning/Big Data/Artificial Intelligence aspects of incorporating the weapon systems onto the battlefield and maintaining engagement superiority will be highly desirable. As part of the digital twin/thread framework our approach will support the cradle-to-grave development of any high-speed missile system.
Keywords: Digital Thread/Digital Twin, Digital Thread/Digital Twin, Digital Engineering, Hardware-in-Loop, Thermal Protection Systems, Reduced Order Models, efficient simulations
