Development of an Automated Volume Mesh Generation CFD Framework for Hypersonic Heat Flux Predictions

Abstract

The workflow of computational fluid dynamics (CFD) solvers traditionally involves a labor-intensive pre-processing stage, which includes case setup and mesh generation, followed by the solver phase and subsequent data post-processing. Particularly in hypersonic applications, mesh generation has predominantly been a manual and cumbersome process, significantly hindering the scalability of large-scale simulations. The time needed for mesh creation escalates with increasing geometric complexity, posing a substantial bottleneck. This PhD research project has developed innovative numerical methods aimed at addressing these challenges to enhance the efficiency and feasibility of complex simulations. This dissertation outlines the creation of the hybrid CHAMPS near body-Cartesian (NBS-Cart) solver framework, designed for automatic volume mesh generation. This new approach has been tested over a wide range of hypersonic heating scenarios and fluid-ablation interaction cases. It integrates a Cartesian grid solver with adaptive mesh refinement to effectively track off-body wake and shock structures, while the NBS component accurately captures strong boundary layer gradients. The efficacy of the Cartesian higher order shock-capturing scheme was studied for a canonical 2D hypersonic cylinder flow and a full 3D Mars Science Lander configuration. This testing confirmed the scheme's ability for efficient shock capturing on non-aligned grids which is desirable for accurate NBS heat flux predictions within the coupled solver paradigm. Furthermore, the solver was integrated with the external KATS material response solver to simulate both steady-state and transient graphite ablation processes. The fluid-ablation coupling approach was validated against existing numerical models and arc-jet test data, showing excellent agreement in predicted surface heat fluxes, thermal responses within materials, and morphological changes resulting from thermo-chemical ablation processes. The final stage of this work focused on the development of low dissipation, higher-order numerical schemes that leverage the NBS structure targeting scale-resolved turbulence flow simulations. A key application involved simulating the Boundary Layer Transition (BOLT-II) flight vehicle at its Mach 6 descent condition. This simulation served as a verification exercise against other CFD codes and existing flight data. The NBS demonstrated its proficiency in accurately capturing the dominant curved shock-induced vortices at the vehicle's leading edge, as well as the outboard cross-flow vortex structures. The heat flux predictions from the NBS aligned closely with published data, underscoring the effectiveness and robustness of the CHAMPS NBS-Cart solver in complex aero-thermodynamic conditions. This newly developed capability provides users with a fully-automated volume mesh generation CFD platform suitable for both low and high-enthalpy hypersonic flight environments. This advancement represents a significant stride towards enhancing CFD workflow automation, facilitating design and production-level simulations for real-world applications. This innovation not only streamlines processes but also increases the accuracy and reliability of simulations in complex aerodynamic scenarios.