DSMC STUDY OF MICRO-ABLATION FOR REENTRY VEHICLES

Hypersonic reentry vehicles are subjected to a severe aerodynamic thermal environment during a high-speed flight. Accurate prediction of micro-ablation process is quite crucial for the design of thermal protection systems (TPS). Since the aerodynamic shape changes due to the ablation process, which in turn will affect the aerodynamic thermal environment around the aircraft and then the ablation process itself, coupled calculation between the ablation and the flow field is required. This study uses the open source DSMC kernel SPARTA to study the micro-ablation phenomena under extreme conditions for the surfaces of hypersonic reentry vehicles. In order to construct and test a general coupling algorithm, significant improvements have been made to the program. The kinetic ablation model in SPARTA is improved based on the one-dimensional ablation model. Besides, the computing method of the ablation rate has been adapted to be more accurate after employing the ablation surface thermal equilibrium model, and the grid corner values are modified combined with the basic characteristics of Marching Square algorithm and the ablation rate. In this paper, the ablation processes of typical aerodynamic shapes such as cylinders, a blunt cone, and a wedge with a small obstacle are simulated and analyzed under two-dimensional conditions. The predicted surface of cone section along the stagnation streamline shows a faster recession rate, which achieves a good agreement with the result in the literature. In addition, the ablation results of the wedge indicate the existence of an extremely rarefied flow region near the obstacle, which undergoes a distinct shape change rapidly along with the head stagnation point after the ablation process happens. These findings have illuminated the characteristics of the micro-ablation process for the hypersonic reentry vehicles, offering valuable guidance for the design of thermal protection systems and advancing our understanding of the ablation mechanisms pertinent to the hypersonic flight vehicles.