Study on JAXA elements for international lunar vicinity mission

JAXA has commenced technical research for contributing as a part of international partnership for the space exploration in Lunar vicinity. One of the candidates is the cargo transport mission with the combination of Cryogenic Propulsion Stage(s) (CPS) and a transfer vehicle derived from Japanese un-manned vehicle used for ISS. The CPS needs advanced technologies to keep the propellant for long mission duration and they will be useful in further missions beyond moon. This paper reports the profile of the mission, vehicle configurations, and the transport capabilities.     

低温推进剂输送与预冷系统间歇泉不稳定性数值模拟研究

针对低温推进剂（液氧）输送与预冷系统间歇泉不稳定性进行了模拟与数值试验研究。分析与验证了连接液氧贮箱的底端封闭垂直管路的典型间歇泉不稳定过程,对经验Murphy曲线进行了检验。针对自然循环型的低温推进剂输送与预冷系统不稳定性及典型间歇泉的发生,进行了稳定域的计算与影响参数分析,研究了过冷度、输送管漏热、发动机进出口阻力、回路高度,以及回流管漏热（保温状况）对各域边界的影响。     

Thermal conductivity studies of a polyurea cross-linked silica aerogel-RTV 655 compound for cryogenic propellant tank applications in space

Silica-based aerogel is an ideal thermal insulator with a makeup of up to 99% air associated with the highly porous nature of this material. Polyurea cross-linked silica aerogel (PCSA) has superior mechanical properties compared to the native aerogels yet retains the highly porous open pore network and functions as an ideal thermal insulator with added load-bearing capability necessary for some applications. Room temperature vulcanizing rubber-RTV 655—is a space qualified elastomeric thermal insulator and encapsulant with high radiation and temperature tolerance as well as chemical resistance. Storage and transport of cryogenic propellant liquids is an integral part of the success of future space exploratory missions and is an area under constant development. Limitations and shortcomings of current cryogenic tank materials and insulation techniques such as non-uniform insulation layers, self-pressurization, weight and durability issues of the materials used, has motivated the quest for alternative materials. Both RTV 655 and PCSA are promising space qualified materials with unique and tunable microscopic and macroscopic properties making them attractive candidates for this study. In this work, the effect of PCSA geometry and volume concentration on the thermal behavior of RTV 655—PCSA compound material has been investigated at room temperature and at a cryogenic temperature. Macroscopic and microscopic PCSA material was encapsulated at increasing concentrations in an RTV 655 elastomeric matrix. The effect of pulverization on the nanopores of PCSA as a method for creating large quantities of homogeneous PCSA microparticles has also been investigated and is reported. The PCSA volume concentrations ranged between 22% and 75% for both geometries. Thermal conductivity measurements were performed based on the steady state transient plane source method.     

A short history of the European Transonic Wind Tunnel ETW

This paper is written as a contribution to the celebration of 50 years of Progress in Aerospace Sciences and of the centenary of the birth of its founder, Dietrich Küchemann. It reviews the evolution of the European Transonic Wind Tunnel, ETW, from early conceptual studies to its entry into service and its current capabilities and achievements. It traces the development, from the earliest days, of experimental aerodynamics and of the basic aerodynamic understanding that gave rise to the main periods of wind tunnel building before and after World War II. By about 1960, this activity appeared to have come to a natural halt. The paper gives an account of the role of Küchemann in arguing the need in 1968 for a further step in wind tunnel capability, to provide transonic testing at high Reynolds numbers. It describes his leading role in gaining acceptance of the concept, formulating the specification and promoting studies of alternative, radical design options for the co-operative European project that became ETW. The progress of ETW through design, construction, commissioning and into full operation is recorded. The paper discusses the many technical innovations that have been introduced in order to meet customer requirements in the challenging field of aerodynamic testing in a cryogenic environment and, finally, looks to the future and the further technical challenges that it holds.     

深空探测用低温推进剂贮箱热力排气系统研究

Cryogenic propellant usually experiences long term on orbit storage. The pressure increase in cryogenic storage tank is faced by most of space missions. The thermodynamic vent system (TVS) is treated as the promising method to control the increase of the tank pressure by scholars both at home and abroad. Based on the investigation conducted by different research agencies, literature review and management are conducted to reflect the recent research statue on TVS. The development profile of the experimental research on the pressure control performance of TVS is specially summarized. The condition setting and performance difference of TVS conducted by different agencies are compared and analyzed. The key technique and related conclusion are refined during the operation of TVS. Finally, based on the requirement of the large scale using of cryogenic propellant in deep space exploration in China, the development plan is proposed on the aspect of TVS pressure control on cryogenic storage tanks.     

运载火箭低温输送系统间歇泉特性及抑制方案探究

为研究重型运载火箭液氧管道中的间歇泉现象并设计有效的抑制方法，调研分析了不同领域中间歇泉的研究现状及低温领域间歇泉的特点。揭示了低温推进剂管道中间歇泉的动态特性和产生机理，提出了重型运载火箭间歇泉抑制方法。研究表明：1)低温领域发生间歇泉的管道结构参数、热流输入方式、液体性质与其他领域相比有较大不同；2)减压沸腾是间歇泉产生的主要原因，弹状气泡不是低温管道中产生间歇泉的必要条件；3)间歇泉过程中会出现剧烈的压力降低和突增现象，在恶劣工况下压力波动可达兆帕量级；4)根据重型火箭的管路布局方式，可选择氦气注入或者外界热流引起循环流动的方法来抑制间歇泉。     

低温推进剂热分层研究

通过详细分析热分层产生的机理,阐述了低温流体热分层所引起的流体温度分布、气液界面现象以及箱体压力增加过程。对有关流体热分层的试验研究以及数值模拟的文献进行了整理;对不同低温流体工质、箱体初始设置参数及尺寸参数、箱体形状、壁面曲率大小、壁面是否加肋片以及箱体晃动旋转等对热分层的影响进行了分类总结;对不同热分层数学物理模型进行了系统对比。介绍了不同重力水平下,流体流动状态与热分层的关系。归纳了有关热分层现象的一些重要结论,阐明了我国在该领域开展研究的必要性。最后指出低温流体热分层对推进剂箱体优化设计及安全运行的重要意义。     

污染低温凝结效应设备的研制

成功研制了星用非金属材料空间分子污染低温凝结效应环模测试设备 ,可原位、连续、定量测量星用非金属材料空间出气物在低温敏感表面上的凝结 ,给出全过程的数据和凝结量级。测试系统功能稳定、测试仪器灵敏、可实现大冷量、宽低温范围的模拟。设备致冷范围为 - 10 0℃～ 2 5℃ ,测试灵敏度为 10 - 8克 ,最优真空度达 7.0× 10 - 6 Pa。是我国目前唯一的用作星用非金属材料空间出气污染物在低温敏感表面上沉积凝结效应定量原位测试的专用环模设备。可用于空间分子污染机理的综合研究、空间分子污染的防护与控制工程。设备兼设有符合国际现行通用标准的星用非金属材料环模评价筛选系统     

适于低温应用的玻璃纤维/聚醚酰亚胺复合材料

采用不同含量玻璃纤维/聚醚酰亚胺制备高性能复合材料,对其超低温(-253℃)线胀系数进行深入研究,并对其常温下的热导率、力学性能进行比较.结果表明,玻璃纤雏质量分数为30%时,复合材料的综合性能优异,其典型性能如下:低温线胀系数纵向为2.16×10~(-5)/K,横向为3.03×10~(-5)/K,热导率为0.31W/(m·K),拉伸强度为158 Mpa,弯曲强度为264 Mpa,无缺口冲击强度为4.24 J/cm~2.