微尺度下固体推进剂燃烧机理研究

In order to confirm the combustion rules at micro-size and resolve the puzzle of low combustion efficiency of solid propellant in micro motor, theoretical simulation and experimental study have been done to research the influence on combustion and flow in micro solid motor and combustion mechanism of solid propellant at micro scale, The influences of some factors (such as propellant formulation, motor configuration, nozzle size and heat loss of case) on combustion performance (burning rate and specific impulse) will be studied by considering the combustion process with unstable overfall fluid, thermo-chemistry and heat exchange of solid propellant at micro scale. The burning rate of grain is measured and the mini impulse of thruster is measured in specific combustor; the combustion process of solid grain in micro-thruster is recorded by using high-speed photograph technique; the numerical simulation on unstable onflow is developed by using CFD technique. Based all studied works, the combustion mechanism and combustion rules of solid propellant will be summarized, and the influence of micro scale effect on combustion and onflow will be confirmed. Some methods or ways will be put forward to improve the combustion efficiency of grain in micro motor. The research results will lay the foundations for high combustion efficiency of propellant in micro solid thruster.

针对固体推进剂在微尺度下燃烧规律不明和推进剂在微型发动机内燃烧效率低的难题，开展微尺度效应对微型发动机内燃烧与流动影响研究。综合考虑微尺度条件下推进剂燃烧所涉及的非稳态流动、热化学和热传导等物理化学过程，研究多因素（推进剂配方、发动机结构、喷管尺寸和壳体散热等）对推进剂燃烧性能(燃速和比冲)的影响。测试不同工况下发动机内药柱燃速特性和发动机冲量特性；可视化测量推进剂在微型发动机内燃烧过程；数值仿真分析微型发动机非稳态湍流流动。通过上述研究，揭示微尺度下固体推进剂燃烧机理，确定微尺度效应对发动机内燃烧与湍流流动影响规律，提出提高微型发动机内固体推进剂燃烧效率的方法与途径，为实现微固体推进器内推进剂高效燃烧奠定基础。

针对固体推进剂在微尺度下燃烧规律不明和推进剂在微型发动机内燃烧效率低的难题，提出了适用于微药柱的推进剂组分筛选原则，开展了AP/NC、HAN/PVA、DINA/AP/Mg三种推进剂体系不同配方药柱能量特性、热解特性、点火特性、火焰结构、燃速特性、比冲特性测试研究，获得了推进剂配方、压强等因素对微药柱点火燃烧特性影响规律。建立了微尺度条件下固体推进剂详细反应机理模型，获得了不同配方条件下绝热火焰温度、临界预混火焰高度、稳态燃烧火焰高度等参数的变化规律。建立了微型发动机内流场非稳态数值仿真模型，数值分析了存在散热损失条件下微型发动机燃烧室、喷管壁面温度和应力分布；获得了壳体材料、喷管结构、散热损失等因素对微型发动机湍流流场和推力特性的影响规律。研究确认微药柱在发动机内工作方式为燃烧，优化后的发动机燃烧效率达88%。由此，总结了微尺度条件下固体推进剂点火燃烧机理，提出了提高微型发动机燃烧效率的方法与途径，为微型发动机装药结构设计、性能仿真提供了有价值的数据支撑，有望推动微型固体发动机技术快速发展。