Numerical investigation on directional transpiration cooling performance coupled with regenerative cooling

In order to improve the cooling performance and drag reduction performance of active thermal protection, this paper proposes to replace the single transpiration cooling with the coupling of directional transpiration cooling and regenerative cooling. The thermal protection and drag reduction characteristics of composite cooling with different directional angles are numerically investigated based on a thermal equilibrium model, utilizing endothermic hydrocarbon fuel as the coolant. The numerical results demonstrate that directional angle hinders the easy outflow of coolant at the starting position of transpiration, leading to localized high temperature phenomena. However, with an increasing directional angle, the enhanced high temperature effect promotes an increase in hydrocarbon fuel cracking degree while weakening the occurrence of local high temperature phenomena. Moreover, the directional angle enhances the stability of coolant adherent flow at the outlet of the porous medium, thereby effectively reducing resistance to high enthalpy airflow through directional transpiration cooling. In summary, the thermal protection performance/drag reduction performance coupling matching characteristics of directional transpiration cooling with the directional angle of 45° are the best in the research range. •A composite cooling model of directional transpiration cooling and regenerative cooling is established.•Directional transpiration cooling causes local high temperature at the starting transpiration position.•Directional transpiration cooling effectively reduces the resistance of coolant to high enthalpy airflow.•The thermal protection and drag reduction performance achieve the best coupling when the directional angle is 45°.