Thermal Loading Analysis of Hypersonic Flight Object with Re-Entry Trajectory by Time-Adaptive Weakly Coupled Conjugate Heat Transfer

This study focuses on assessing the thermal loading experienced by an object re-entering from altitude 60km with hypersonic speed along a specified trajectory.Traditional approaches employ strongly coupled conjugate heat transfer to address the transient flow and heat transfer interaction, necessitating extremely small time steps in unsteady flow solvers due to hypersonic conditions.However, the computational cost becomes prohibitively high, exceeding a decade for a flight time around 100 seconds.In response, this paper introduces a novel time-adaptive weakly coupled conjugate heat transfer method.This approach determines coupling times between flow and heat transfer solvers based on changes in wall heat flux and temperature.The methodology in this paper also addresses challenges such as hypersonic flow, gas chemical reactions, aerodynamic heating, and surface ablation.The trajectory is initially established using flight dynamic theory, providing time-varying free stream conditions.Computational Fluid Dynamics (CFD) predicts flow field information including shockwaves, chemical reactions, and aerodynamic heating.Thermal loading on the wall is considered in conjunction with a Thermal Protection System (TPS), employing carbon-based materials.The model accounts for gas and surface material reactions, including ablation reactions in carbon-based materials, with surface shape changes implemented using User-Defined Function (UDF) custom code.This integrated approach not only reduces computational costs but also enables real-time monitoring of surface thermal loads and structural heat transfer variations due to time-dependent free stream conditions.At the end of the paper, a practical empirical relationship is presented, establishing a correlation between thermal loads at the stagnation point and the free stream conditions throughout the flight.The utilization of this straightforward empirical equation provides a valuable tool for designing effective thermal protection systems and optimizing trajectories in the realm of future hypersonic applications.