Flow and heat transfer characteristics of hydrocarbon fuel in lightweight C/SiC regenerative cooling combustor

To meet the requirements of higher thermal protection ability and lower structural weight of regenerative cooling structures in advanced hypersonic vehicles, carbon-fiber-reinforced silicon carbide (C/SiC) composites with high permittable service temperatures and low densities are promising for application in thermal protection systems. In this study, four cylindrical regenerative cooling configurations applying C/SiC composites for a designated scramjet engine combustor are proposed, and the thermal protection performance under the influence of the cooling equivalence ratio (0.4∼1.0) and anisotropic thermal conductivity is studied. The results show that the C/SiC composites can significantly improve the heat resistance of the entire regenerative cooling structure owing to their relatively low thermal conductivity, which reduces the total heat flux transferred to the inner structure. The thermal protection ability can be maintained, whereas the coolant flow rate is reduced by 50%. C/SiC composites with higher thermal conductivities in the circumferential direction are beneficial for uniform temperature distribution. A flow distribution deterioration phenomenon caused by the thermal cracking of the coolant and the increasing flow resistance in the cooling channels can be observed under certain conditions, leading to a mass flow rate difference of 2.5 times among the cooling channels. Moreover, introducing C/SiC composites into the regenerative cooling structure design can significantly reduce the total structural weight by over 50% compared to traditional superalloys.