Analysis of Heat Transfer and Flow Structures of Supercritical n-Decane in Regenerative Cooling Channels Combining Different Thermal Protection Materials

As hypersonic aircraft applications become increasingly extreme, traditional regenerative cooling channels primarily using high-temperature alloys as wall materials can no longer simultaneously meet the dual requirements of thermal protection and lightweight design. This study, based on hypersonic environments with Mach numbers exceeding 8, selects five materials with significant advantages from metals, ceramics, and C/SiC composite materials to conduct a coupled design of wall materials for the flow and heat transfer characteristics of n-decane under 3 MPa pressure. The results show that the heat transfer ability of different material combination schemes is closely related to the thermal–physical properties of the materials, and the materials with obvious advantages in specific thermal–physical properties are dominant. Under a heat flux of 1.5 MW/m2, the GH3128 + Cu composite scheme demonstrates a 17.5% increase in Nusselt number and a 17.6% improvement in comprehensive heat transfer coefficient compared to the traditional high-temperature alloy scheme. When the heat flux triples to 4.5 MW/m2, the temperature variation of the GH3128 + Cu composite scheme is only 50% of that of the steel + C/SiC composite scheme. This indicates that multi-material coupling exerts both synergistic effects and inhibitory effects on flow and heat transfer characteristics, highlighting the importance of flexible material selection tailored to different tactical and technical requirements.