Numerical investigation of convective-transpiration coupled cooling performance with coolant of supercritical CO2 for scramjet

The supercritical CO 2 (SCO 2 ) Brayton cycle applied to cool scramjet on hypersonic vehicle is a promising thermal management scheme. However, the huge thermal load in the combustion chamber makes it difficult for the single convection cooling method to meet the cooling demand at high Mach number ( Ma ≥ 8). This study proposes a convective-transpiration coupled cooling scheme using SCO 2 . The results show that the convective-transpiration coupled cooling method using SCO 2 provides effective thermal protection for porous media walls, achieving a cooling efficiency of over 97%. Different inlet temperature and pressure influence state transition behavior, as well as the flow and heat transfer characteristics, thereby affecting the cooling performance. Notably, increasing the inlet pressure of the coolant delays the occurrence position of the pseudo-critical zone, and then the overall cooling performance can be enhanced. Additionally, the convective-transpiration cooling method is integrated with a SCO 2 -based cooling system to evaluate the leakage of CO 2 over a fixed cruise period. The leakage ratio is approximately 0.15% and the total leakage is approximately 4.32 kg during a 30-min cruise. The proportion of total leakage to filling amount is only 4.32%, which can be replenished by carrying additional coolant to replenish which wouldn’t result in serious quality penalties.