Investigation on heat transfer and heat sink distribution of regeneration-transpiration combined cooling

A numerical model of regeneration-transpiration combined cooling is constructed to investigate the thermal protection characteristics. The influence of the coolant mass flow distribution ratio and non-uniform heat flux on the heat transfer performance is examined under both single-channel and parallel-channel configurations of the combined cooling system. In comparison to regeneration cooling, the combined cooling exhibits a significant enhancement in the cooling effect. Transpiration cooling can more effectively utilize the heat-carrying capacity of the coolant and assumes a predominant role in heat absorption within the combined cooling system. As the non-uniformity of the heat flux applied to the porous medium escalates, the non-uniformity of the transpiration coolant mass flux and the effective heat transfer coefficient rises, while the heat sink ratio of transpiration cooling to regeneration cooling declines. A negative feedback mechanism between the coolant mass flux and the thermal load is established in the parallel channels under a non-uniform thermal load, causing more coolant to flow towards the high-heat-flux region. With an increase in the non-uniformity of the thermal load in x direction, the disparities in velocity, coolant mass flow rate, and heat sink ratio distribution within the parallel channels of the combined cooling system become more pronounced.