【作者】 胡凡；

【导师】 张为华；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2008， 博士

【摘要】 水冲压发动机属新概念推进系统,采用高能金属燃料,利用海水作为氧化剂,具有比冲高、结构简单和安全性好等优点,是满足未来水中兵器高航速和远航程的最佳动力系统。本文以镁基燃料水冲压发动机为研究对象,采用理论分析、数值模拟和试验研究相结合的方法,对发动机工作过程及性能开展系统研究,实现了发动机稳定工作,提高了发动机性能,为发动机设计提供了理论基础。在分析水冲压发动机工作过程基础上,建立了发动机热力循环模型,应用热力计算方法研究了金属燃料配方、工作参数及凝相产物对发动机理论性能的影响,分析了壅塞式和非壅塞式发动机构型性能调节能力,重点研究了非壅塞式构型性能调节特点和规律。建立了镁基燃料水冲压发动机一维两相多组分反应流计算模型,推导了镁水化学反应动力学模型,进行了发动机流场一维数值模拟,通过与试验结果对比分析,对程序有效性进行验证并修正模型,分析了稳态工作时发动机一次和两次进水流场特性,为在设计阶段快速获得性能参数提供了研究手段。建立了发动机内三维多相湍流仿真模型,开展了发动机内流场三维数值模拟研究,分析了一次与两次进水后发动机内燃烧流动过程,将仿真结果与试验测量结果比较,验证了模型正确性,为研究发动机构型及工作参数对性能影响提供了理论基础。通过发动机内三维数值模拟,研究了进水量、射流速度、进水孔数、雾化液滴直径、进水位置及发动机结构等因素对发动机性能的影响,得到不同构型和进水参数下发动机内流场分布及性能变化规律,为合理设计发动机和提高发动机性能提供了理论依据。设计了水冲压发动机试验系统及发动机,提出了工作参数设计及试验数据处理方法,通过试验研究了镁基燃料一次燃烧性能,实现了发动机进水后稳定工作,研究了四种发动机构型、一次水燃比和燃速等对发动机工作过程和燃烧效率的影响,进行了发动机两次进水试验,显著提高了发动机性能,试验结果为水冲压发动机研制与应用提供了重要技术支撑。本文研究成果将促进镁基燃料水冲压发动机应用技术的发展,对未来高速水中兵器动力系统研究具有重要理论价值和工程实践意义。更多还原

【Abstract】 Water ramjet as a new concept propulsion system takes high-energy metal fuel and uses water as oxidizer. For merits of high specific impulse, simple structure and good safety, it is the best propulsion system for the future subaqueous weapon of high speed and long voyage. In this dissertation, focusing on the magnesium-based fuel water ramjet, the operation process and the performance of the engine are investigated systematically using the method of theory analysis, numerical simulation and experiment. The stable operation of the engine is achieved, and the performance is improved remarkably. The results can provide theoretical basis for the design of water ramjet.Based on the analysis of the operation process of water ramjet, the model of thermal cycling is established. The influences of metal fuel composition, work parameters and condensation phase product on the theoretical performance are researched by thermal calculation. The ability of performance adjustment of the choked and unchoked water ramjet is analyzed, and the unchoked water ramjet is studied in detail.The 1-D, two phases, multi species and reacting flow model of magnesium-based fuel water ramjet is established, and the chemical dynamics model of magnesium-water is derivated. The flow field of the engine is calculated based on the 1-D simulation model. Through comparing the calculation results with the experiment results, the validity of program is validated and the model is modified. The characteristic of the flow field is analyzed when the engine operates stably after once and twice water injection. The program can provide research means for obtaining performance parameter quickly at the design stage.The 3-D numerical simulation of magnesium-based water ramjet is developed based on the 3-D, multi-phase turbulent simulation model. The process of combustion and flow after once and twice water injection in the engine is analyzed. The model is validated by the experiment results, and it is the theoretical basis for investigating the influences of structure and work parameters on the performance of water ramjet. The variety law of the performance and the distribution of the flow field for the water ramjet are obtained through 3-D numerical simulation under different work parameters such as water injection mass, velocity, position, number of the orifice, the diameter of the atomization droplet and the structure of the water ramjet. The results can provide theoretical basis for designing the engine reasonably and improving the performance.The engine and the system for water ramjet experiment are designed, and the method of the operation parameter design and experiment data handling are also presented. The once combustion performance of magnesium-based fuel is surveyed through the experiment. After realizing the stable work of the experiment engine, the influence that four structures of the engine, once water/fuel ratio, and the burn rate of the fuel make on operation process and the combustion efficiency of the engine are researched. The experiment of twice water injection is developed, and as a result the performance of the experiment water ramjet is improved remarkably. The experiment results can provide important technical support for manufacturing and applying the water ramjet.The conclusions achieved in the dissertation will surely promote the application of the magnesium-based water ramjet. Therefore the research will be of great theoretical value as well as engineering practice meaning for the propulsion of the future high speed subaqueous weapon research.更多还原