Time-Accurate Hypersonic Modeling for Morphing Vehicles

Next-generation hypersonic vehicles must be designed for increased dynamics, control, and maneuverability to achieve enhanced tactical performance, speed, reach, and lethality. Morphing and adaptive structures, as well as active control surfaces, will be critical in achieving these goals. Changes in vehicle orientation and configuration along the vehicle flight path produce non-linear variations in freestream conditions, chemical kinetics, vibrational excitation, turbulence, ablation products, and gas-surface interactions, all of which affect the detectable emission spectra of the vehicle. Consequently, the emission intensity is also time-varying, making it particularly difficult to predict time-accurate electromagnetic (EM) signatures along the trajectory of a morphing vehicle. Designing high-performance morphing vehicles, therefore, requires highly accurate, tightly-coupled, physics-based modeling of these rate effects across a wide range of time scales. This R&D effort focuses on adding a Ātime-accurate toolkit to SSIÆs Hypersonic Scenes from Extreme Aerothermodynamics Systems, HySEAS. HySEAS is a robust framework of tools to couple high-fidelity, steady-state computational fluid dynamics and radiative transport models for end-to-end EM predictions over hypersonic trajectories. In Phase I, we implemented new capabilities for in-the-loop CFD mesh morphing and demonstrated capability for high-fidelity turbulence modeling. US3D was coupled with the novel TASC plugin for trajectory control and ablation modeling, and the EO/IR signature was predicted using SPPM-US3D. Phase I results for the end-to-end problem of a morphing hypersonic waverider over a full trajectory proved that our prototype toolkit can effectively capture time-dependent changes along the flight path. Substantial variations in the spectral intensity were predicted from changes to the vehicle shape in-flight, ablation effects, turbulence, altitude, and Mach number. In Phase II, we will develop new features and improve existing capabilities. We anticipate studying complex morphing geometries, and those which have existing validation/verification data available. We will expand our time-accurate toolkit to morph both fluid and solid CFD grids under ōactiveö morphing, such as a geometric change, and ōpassiveö shape-change, such as leading-edge erosion. Concurrently, our partners will focus on high-fidelity turbulence modeling with a particular focus on improving estimates for transition to turbulence. Since it is impractical to utilize these high-fidelity turbulence methods within a trajectory simulation loop, results will be used to identify pathways for optimizing RANS modeling within the HySEAS framework. The predicted flow-field will then be post-processed to obtain EO/IR and RF signatures for a morphing vehicle over a full trajectory.