Coupled Aerothermal Prediction of Ablative Hypersonic Re-entry Vehicles with Ansys Fluent and Ansys Thermal Desktop

Thermal ablation is a critical process in aerospace engineering, particularly for the design and operation of launch vehicles and re-entry systems. Ablative Thermal Protection Systems (TPS) are essential for protecting hypersonic re-entry vehicles from intense heating during re-entry. Designing TPS through ground and flight testing is not only challenging but also costly. High-fidelity numerical simulations offer a valuable alternative for studying aerothermal heating, especially under radiative and thermo-chemical non-equilibrium conditions, and for evaluating the thermal response of heatshield materials. In this study, we validate our computational fluid dynamics (CFD) approach and results against experimental data obtained at the IHF arc-jet facility at NASA Ames Research Center, focusing on a carbon-based nose tip for a re-entry vehicle. Different approaches to thermal ablation modelling are explored using Ansys Fluent’s density-based coupled (DBNS) CFD solver and Ansys Thermal Desktop (TD). TD, a 3D thermal simulation tool, simulates material recession in one dimension based on applied heat from melting or sublimation, without considering in-surface heat transfer. While material recession is modelled by removing mass and energy, the shape of the model remains unchanged as the sublimated or melted material is shed from the surface. This method simplifies ablation physics, making it useful for fast simulations in early design stages. Additionally, an optimized, adaptable, loosely coupled aerothermal ablation approach for both single flight conditions and flight trajectories is proposed using Ansys System Coupling, a Multiphysics co-simulation tool.