Numerical investigation of a self-adaptive transpiration cooling system with an ablative layer in directional porous structures

Transpiration cooling is a highly promising thermal protection technology. However, traditional porous structures are susceptible to local thermal blockage under non-uniform heat flux, potentially leading to vehicle failure. This study proposes a directional porous structure with an ablative layer and investigates the effects of adaptive ablation, coolant injection methods, degrees of orientation, and structural optimization on transpiration cooling performance through numerical simulations. The results show that the addition of an ablative layer significantly enhances the performance of isotropic porous structures, improving temperature distribution, reducing peak temperature by approximately 50 %, and minimizing coolant waste. The dynamic evolution of the ablative layer follows an intermittent opening pattern at a pyrolysis temperature of 1000 K, while at 800 K, the openings occur sequentially from the high heat flux region. The study further explores the impact of a multi-chamber configuration on cooling performance, revealing that decreasing the baffle to stagnation point distance can effectively reduce both solid temperature and coolant pressure. To balance efficient cooling with structural complexity, a quantitative analysis identifies the optimal configuration, where the baffle to stagnation point distance is one quarter of the model width. This study provides an effective approach for designing high performance thermal protection systems.