关键词: 冷却通道；超临界压力；甲烷；传热恶化；异常热传导；数值研究

Abstract: In order to deeply understand the flow and heat transfer characteristics of hydrocarbon fuels in the regenerative cooling process of rocket engines，a numerical study on convective heat transfer of supercritical methane in square cooling channels with asymmetric heating imposed on the top exterior channel surface was conducted based on the RNG k-ε turbulence model with enhanced wall treatment. The heat transfer deterioration at the internal heating wall，and the abnormal heat flux transmission phenomenon due to the combined effects of heat transfer deterioration and wall heat conduction，were investigated in detail. The empirical corrections for critical heat flux and initial internal-wall temperature of heat transfer deterioration have been successfully obtained. Furthermore，the expressions for averaged heat flux predictions at the top and side internal walls have also been effectively established. Results indicate that when the ratio of exterior wall heat flux and mass flux is higher than 0.288kJ/kg，the flow acceleration effect occurs in the near-wall region at the internal heating wall，and thus leads to a significant heat transfer deterioration phenomenon. Meanwhile，the heat flux decreases at the internal heating wall，and more heat flux transmits to the side internal wall surface，resulting from the temperature distortion in the solid region. This phenomenon is more obvious with the decrease of pressure.

Key words: Cooling channel；Supercritical pressure；Methane；Heat transfer deterioration；Abnormal heat conduction；Numerical study