Abstract Thermal choke is commonly employed in a fixed geometry RBCC combustor to eliminate the need for physically variable exit geometry. This paper proposed detailed numerical studies based on a two-dimensional integration model to characterize thermal choke behaviors driven by various embedded rocket operations in an RBCC engine at Mach 4 in ramjet mode. The influences of different embedded rocket operations as well as the corresponding secondary fuel injection adjustment on thermal choke generation process, the related thermal throat feature, and the engine performance are analyzed. Operations of embedded rocket bring significant effects on the thermal choke behaviors: (1) the thermal throat feature becomes much more irregular influenced by the rocket plume; (2) the occupancy range in the combustor is significantly lengthened; (3) the asynchrony of the flow in different regions accelerating to sonic speed becomes much more significant; (4) as the rocket throttling ratio decreases, the thermal choke position constantly moves upstream integrally, and the heated flow in the top region that is directly affected by the rocket plume reaches sonic speed more rapidly. Finally, we can conclude that appropriate secondary fuel injection adjustment can provide a higher integration thrust for the RBCC engine with the embedded rocket operating, while the thermal choke is stably controlled, and the increased heat release and combustion pressure are well balanced by the variations of pre-combustion shocks in the inlet isolator.

中文翻译：

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RBCC发动机冲压式喷气发动机各种火箭工作驱动热阻流行为的数值研究

摘要 热扼流圈通常用于固定几何形状的 RBCC 燃烧器，以消除对物理可变出口几何形状的需要。本文提出了基于二维积分模型的详细数值研究，以表征由各种嵌入式火箭在 RBCC 发动机中以冲压喷气模式运行的 4 马赫的热阻行为。分析了不同嵌入式火箭操作以及相应的二次燃料喷射调整对热阻产生过程、相关热喉特征和发动机性能的影响。嵌入式火箭的运行对热阻行为产生显着影响：（1）受火箭羽流影响，热喉特征变得更加不规则；(2)燃烧器内的占用范围显着延长；(3)加速到声速的不同区域内流动的不同步性变得更加显着；(4)随着火箭节流比的减小，热阻流位置不断整体向上游移动，受火箭羽流直接影响的顶部区域的热流更快地达到音速。最后，我们可以得出结论，适当的二次喷油调整可以为嵌入火箭运行的 RBCC 发动机提供更高的集成推力，同时稳定控制热阻，增加的放热和燃烧压力通过入口隔离器中的预燃冲击。热阻流位置不断整体向上游移动，受火箭羽流直接影响的顶部区域的热流更快地达到音速。最后，我们可以得出结论，适当的二次喷油调整可以为嵌入火箭运行的 RBCC 发动机提供更高的集成推力，同时稳定控制热阻，增加的放热和燃烧压力通过入口隔离器中的预燃冲击。热阻流位置不断整体向上游移动，受火箭羽流直接影响的顶部区域的热流更快地达到音速。最后，我们可以得出结论，适当的二次喷油调整可以为嵌入火箭运行的 RBCC 发动机提供更高的集成推力，同时稳定控制热阻，增加的放热和燃烧压力通过入口隔离器中的预燃冲击。