超燃冲压发动机的再生冷却系统对于高超声速飞行器的安全和性能有着重要意义，飞行器马赫数的不断提升导致发动机的再生冷却系统的热环境更加苛刻。碳氢燃料的热裂解以及水与碳氢燃料发生的催化重整等化学反应有效提升再生冷却系统的性能，因此探究化学反应影响下燃料的换热规律对未来更高马赫数飞行器的超燃冲压发动机冷却系统的发展具有十分重要的意义。首先，本文通过实验研究含水碳氢燃料的定压比热容变化规律，揭示了由于相变引起的两个定压比热容峰值特征，构建了考虑实际气体效应的不互溶混合物流体饱和蒸汽压计算模型，以及含水碳氢燃料定压比热容预测模型。其次，通过实验研究超临界吸热型碳氢燃料流动换热规律。在非化学反应换热区，碳氢燃料在拟临界温度附近在热加速效应的作用下出现换热强化。在化学反应影响换热区，热裂解反应提升了燃料的换热性能，其吸热效应大大强化换热过程，而化学反应导致的物性变化则对换热有不利影响。之后，探究含水碳氢燃料流动换热规律。在非化学反应换热区，燃料相变导致沸腾强化换热，含水碳氢燃料换热系数在第一个定压比热容峰值点存在一个换热系数峰值，同时在汽化吸热强化换热与过热蒸汽恶化换热的综合作用下，在气液区存在第二个换热系数峰值。在化学反应影响换热区，催化重整反应作为壁面吸热化学反应促进换热性能，在本文的研究范围内，水质量分数为10wt%的含水碳氢燃料催化重整工况的热沉以及换热性能均优于超临界吸热型碳氢燃料热裂解条件下的性能。质量通量以及压力等因素的变化会影响到冷却通道中催化重整反应的相对占比，进而影响换热性能。最后，通过数值模拟研究了不均匀热流条件下碳氢燃料的换热性能。小宽度通道内燃料质量通量大，且壁面热量分配更充分，适用于高热流区域，避免局部高温。大宽度通道促进壁面化学反应，提升燃料的化学热沉。综合热流以及换热分区，匹配优化设计变截面冷却通道，兼顾较好的换热性能以及燃料化学热沉的充分利用。并将结构优化方案应用在真实超燃冲压发动机复杂热环境的冷却系统中，同时通过试验验证了催化重整工况的热沉以及换热特性均优于超临界碳氢燃料热裂解。

With the development of hypersonic vehicles, the heat flux of the scramjet engine thermal protection system has increased sharply. The regenerative cooling system with hydrocarbon fuel going through thermal endothermic reaction, has been recognized as an efficient way to improve the fuel heat sink and cooling performance. Therefore, it’s very important to investigate the heat transfer performance of the fuel under the influence of the chemical reaction for the design and development of the regenerative cooling system for hypersonic vehicles.Firstly, the specific heat capacity at constant pressure of the mixture, containing water and hydrocarbon fuel, were studied through experiments, where two unique peaks characteristics of specific capacity were detected. A model for immiscible fluid mixture saturation vapor pressure calculation which considered the real-gas effect was established to reveal the phase change process of the mixture. Based on theoretical analysis, a prediction model for specific heat capacity of water and hydrocarbon mixture was constructed. The model was validated for the mixture with different water contents and under different pressuresSecondly, a series of the heat transfer experiment with supercritical endothermic hydrocarbon fuel was conducted. In the non-chemical reaction region, the heat transfer enhancement near the pseudo-critical temperature was detected, mainly due to thermal acceleration effects. In the region where the chemical reactions affected the heat transfer process, the thermal cracking reaction improved the heat transfer performance, and its endothermic effect greatly enhanced the heat transfer process, while the physical property changes caused by the reaction had an adverse effect.Then, the heat transfer performance of the mixture, containing water and hydrocarbon fuel was experimental investigated. In the non-chemical reaction region, water boiling enhanced heat transfer, and the mixture achieved a heat transfer coefficient peak at the same temperature with its first specific heat capacity peak. While at the same time, the superheated gaseous result from the vaporization could exert negative influences on the heat transfer process. This resulted in the second heat transfer coefficient peak in the gas-liquid region. In the area where the chemical reactions affected the heat transfer process, as endothermic chemical wall reactions, the catalytic steam reforming reaction promoted the heat transfer performance. In this paper, the heat sink and heat transfer performance of the mixture with a water mass fraction of 10wt% were both higher than those of the supercritical endothermic hydrocarbon fuel under thermal cracking conditions. Mass flux and pressure affected the relative proportion of the catalytic reforming reaction in the cooling channel, thereby affecting the heat transfer performance.Finally, the heat transfer performance of hydrocarbon fuels with non-uniform heat flux was studied by numerical simulations. It is found that the smaller cooling channel width, the lower the heat flux on the inner wall surface of the heated-wall, and the larger the heat transfer coefficient. Therefore, the smaller width could prevent the local high temperature in the high heat flux area. The wider cooling channel promotes the chemical reactions on the wall surface and improves the chemical heat sink of the fuel. Based on the distribution characteristics of heat flow and fuel temperature, the variable cross-section cooling channel was matched and optimized, to achieve a better heat transfer performance and the full utilization of the fuel chemical heat sink. And the structural optimization scheme was applied to the cooling system of the real scramjet engine. At the same time, it is verified by real scramjet engine experiments that the heat sink and heat transfer characteristics of catalytic steam reforming were better than those of supercritical hydrocarbon under thermal cracking conditions.