支板火箭基组合循环发动机激波串/燃烧耦合及燃烧模态转换研究

Isolator-combustor interactions, as one of the typical combustion flow phenomena, occur in all practical transonic, supersonic and hypersonic vehicles. In this project, a central-strut Rocket Based Combined Cycle (RBCC) model combustor would be designed and the underlying physics relating to the formation of the shock train and its movement, the combustion mode and its transition would be revealed. Based on the flow visualization such as the Schlieren technique and the high-speed camera, the process of the shock train formation would be studied under the condition of rocket jet injection. Both the cold and combustion experiments would be carried out to obtain the structure and the properties of the shock train. To provide an adequate description of the complex behavior such as flame dynamics, heat release, shock train, combustion mode transitions and their interactions, analysis of both the pressure distribution and the flame structure is conducted. After that, a new method which applies the primary rocket jet is proposed and investigated. Then an appropriate method is established to make sure the process of the combustion mode transition is stable. Thus, this project attempts to further understanding of the compressible turbulence, shock train and flame dynamics in RBCC combustor configuration and the results could provide theoretical reference on engineering optimal design.

隔离段-燃烧室耦合工作是高超声速动力系统中的典型燃烧流动特征。本项目结合火箭冲压组合发动机（RBCC）中大占空比支板火箭特点，开展支板火箭RBCC发动机中激波串结构和运动、燃烧模态及其转换问题研究。通过高速纹影、高速录像等光学测量手段及冷流与燃烧流相结合的实验方法，研究支板火箭射流作用下隔离段-燃烧室激波串产生与发展的过程，获得激波串结构特征和运动规律；结合流道压强分布与火焰面结构形态特征分析，揭示火焰面移动、燃烧室释热分布与激波串的耦合作用机理，阐明燃烧模态及其转换机理，研究基于支板火箭射流实现燃烧模态平稳转换的控制策略，建立模态平稳转换控制方法，为实现支板火箭RBCC发动机可控燃烧、发动机流道优化设计等提供理论依据。

火箭冲压组合发动机是未来高超声速飞行器和可重复使用天地往返航天运输系统的主要的动力形式。支板式火箭冲压组合发动机隔离段具有大占空比的中心支板，其隔离段-燃烧室耦合工作具有与一般双模态超燃冲压发动机不同的特性。激波串是是实现进气参数和燃烧隔离耦合的纽带，对进气道稳定工作和高效燃烧具有重要的作用。本项目针对激波串特征、燃烧模态及燃烧模态转换等问题开展了实验、数值计算及理论研究。研究了背压、当量比、来流总温、火箭工作状态等参数对激波串结构及激波串位置的影响研究，获得了支板火箭RBCC发动机激波串结构及移动的影响规律；研究了当量比、燃烧模态等条件下支板火箭RBCC发动机燃烧室火焰面特性研究，获得了发动机火焰结构和火焰特征；研究了燃烧与激波串耦合影响关系，揭示了激波串/燃烧耦合机理，建立了隔离段和燃烧室耦合作用的一维分析模型；开展了不同燃烧模态特征分析，获得了燃料喷注位置、凹腔位置及支板火箭射流状态对燃烧模态转换的影响规律，建立了模态转换控制方法。研究获得的主要结果为RBCC发动机燃烧组织、模态过渡策略制定及控制及发动机工作稳定性分析提供了理论支撑。