Abstract: Analysis of rocket jet and secondary combustion to thermal environment on pylon under high thermal load was carried out for RBCC engine at Mach 5.5 with different operating mode and active thermal scheme was designed. At the rocket-scramjet mode， pylon was heated by rocket plume and secondary combustion whose thermal environment was the most serious which presents a trend of “high-low-high” in the direction of flow because the protection of film formed by fuel injection. Based on rocket-scramjet working mode， comparing three kinds of channel layout found that increasing number of channels and flow rate would improve cooling effect at severe highly heated parts and uniformity of temperature distribution which kept the engine work stably for a long time. Adopting kerosene after cooling makes engine thrust increase 1.5%.

Key words: Rocket based combined cycle；Pylon；Thermal environment；Active cooling；Numerical simulation

摘要： 分析了RBCC发动机在5.5Ma条件下不同工作模式时燃料支板所处的热环境，综合火箭射流以及二次燃烧对热环境的影响，设计了带有冷却通道的燃料支板主动热防护方案。研究发现燃料支板在火箭冲压工作模式下受火箭羽流以及二次燃烧双重加热的影响，热环境最为恶劣，燃料喷注所形成的液膜可以对支板中部起到保护作用，壁面温度沿气流方向整体呈“高-低-高”的分布趋势。在此种工作模式下开展了三种冷却通道方案的对比研究，结果表明通道数及单通道流量增加均可以降低受热严峻部位的表面温度，提高支板表面温度的均匀性，保障发动机长时间安全工作。采用开环冷却后的煤油组织燃烧，发动机比冲性能具有1.5%的提高。

关键词: 火箭基组合循环；燃料支板；热环境；主动冷却；数值模拟