低温液体高效预冷管路对于运载火箭快速发射具有重要的工程应用价值。已有研究发现，液氮预冷中可见全部沸腾区，且反环状流膜态沸腾居于主导，而氢预冷未见反环状流膜态沸腾。为揭示差异性现象的内在机理，本项目以低温液体大温差快速预冷所形成的反环状流膜态沸腾为对象，以探究反环状流发生亥姆霍兹不稳定性为切入点，通过理论分析、数值仿真与实验测试相结合的手段，确定预冷过程反环状流的形成条件与流型不稳定性的发生边界。对比分析揭示管流Re数、流体物性、管内壁几何结构对反环状流型演化及热质传递规律的影响，探明氢预冷特殊现象的成因。通过高压、高速预冷可视化实验，揭示管流Re数对不同沸腾模式主导温区迁移规律的影响。针对项目所提出的新型内微肋管，采用数值仿真与实验测试，揭示内微肋结构对加速反环状流型演变的作用规律，验证其对预冷速率提升的有效性。本项目工作有助于理解低温预冷的特性，并为低温管路快速预冷方案设计提供理论支撑。

High-efficiency pipeline precooling technology of cryogenic liquid is significant for rocket rapid launching task. Existing researches indicated that all of boiling mechanisms could be observed in liquid nitrogen precooling operation, and inverted annular flow film boiling played a dominant role in the pipeline chilldown process. For the precooling issue of liquid hydrogen, however, only transition boiling and nucleate boiling were observed during the quenching period but no inverted annular flow film boiling was included. To reveal the mechanisms for the phenomena difference, theoretical analysis, numerical simulation, and experimental study are adopted comprehensively to conduct the associated researches, and the inverted annular flow film boiling produced by larger temperature difference quenching and rapid transfer of cryogenic liquid is selected as the research objective. Through analyzing Helmholtz instability characteristics, the formation conditions as well as the instability boundaries for inverted annular flow are obtained and discussed. Moreover, the influences of precooling flow Reynolds number, fluid properties, and geometric structures of inner wall on the evolution of inverted annular flow pattern and associated heat and mass transfer are studied comparatively, and the reason for the special phenomena of hydrogen precooling is clarified. With the help of high-pressure, high-mass flux precooling visualization experiments, the influence of Reynolds number on transfer feature of dominated temperature range by different boiling regimes are analyzed. In addition, numerical simulation and experimental approach are used to assess the performance of a proposed novel inner micro-ribbed tube. The influence of micro-ribbed tube on enhancing the instability of inverted annular flow and the effectiveness of micro-ribbed tube on improving precooling performance are validated and analyzed. Generally, the works in the present project are beneficial for understanding the cryogenic precooling characteristics, and could provide theoretical support for the future rapid precooling technology.