Ground-based investigations on phase-moving phenomenon with space sublimation cooling for lunar exploration missions

The lunar surface is a typical vacuum environment, and its harsh heat rejection conditions bring great challenges to the thermal control technology of the exploration mission. In addition to the radiator, the sublimator is recommended as one of the promising options for heat rejection. The sublimator makes use of water to freeze and sublimate in a porous medium, rejecting heat to the vacuum environment. The complex heat and mass transfer process involves many physical phenomena such as the freezing and sublimation phase change of water in the porous medium and the movement of the phase-change interface. In this paper, the visualized ground-based experimental approaches of space sublimation cooling were presented to reveal the moving law of three-phase point and the growth phenomenon of ice-peak and icicle in microchannels under vacuum conditions. The visualized experiments and results prove that the freezing ice is divided into the porous ice-peak and the transparent icicle. As the sublimation progresses, the phase-change interface moves downward steadily, the length of the ice-peak increases, but the icicle decreases. The visualized experiments of space sublimation cooling in the capillary have guiding significance to reveal the sublimation cooling mechanism of water in the sublimator for lunar exploration missions.     

大型低温液体火箭“零窗口”发射技术

我国大型低温液体运载火箭组成系统多、各系统耦合关联程度大、射前流程复杂，实现“零窗口”发射难度大。基于大型低温液体运载火箭的系统特点和射前约束条件，提出了实现“零窗口”发射的技术方案。通过能力挖潜主动拓展了任务故障适应性和窗口宽度，并辅以科学的测试发射策略，将技术和流程相结合，共同实现大型低温运载火箭“零窗口”发射目标。这对全面提升大型运载火箭和发射场“零窗口”发射能力、适应未来航天发展需求具有十分重要的意义。