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111.
112.
N_2O单组元微推进系统贮箱自增压特性 总被引:1,自引:0,他引:1
建立了氧化亚氮(N2O)贮箱自增压地面试验系统,针对亚牛级氧化亚氮单组元微推进系统的推进剂自增压供给过程开展了初步测试试验.基于三区域集总参数物理模型建立了氧化亚氮单组元微推进系统贮箱自增压数学模型,针对相同试验条件下的贮箱自增压过程开展了数值模拟,模拟结果与试验数据吻合较好,验证了仿真模型的准确性.仿真及试验结果均表明,为了确保推力器工作全过程中推进剂供应稳定,在亚牛级氧化亚氮单组元微推进系统的自增压过程中需要对氧化亚氮贮箱进行热量补偿来保证贮箱压力的稳定性,而贮箱压力下降速度分别随着贮箱初始充填率的减少、贮箱容积的减小及氧化亚氮质量流率的增加而增大. 相似文献
113.
双组元统一推进系统减压器稳定性仿真 总被引:4,自引:1,他引:4
针对某双组元统一推进气路系统采用的高压卸荷膜片式减压器,建立起有限体积瞬变仿真模型,并搭建起减压器特性研究系统的模块化仿真模型.针对试验过程中出现的振荡现象,借助数值手段阐明了各结构和控制参数对减压器工作稳定性的影响,得出了减弱振荡的各种措施:减小阀芯质量,增大高、低压腔体积,增大弹性元件材料的阻尼系数,减小反馈孔直径,增大膜片刚度.与试验和相关文献研究情况的对比证实了某些措施的有效性. 相似文献
114.
舱外航天服热设计技术 总被引:1,自引:0,他引:1
提出了舱外航天服热设计技术的研究内容,回顾了国内外在该领域的研究现状.分析了二维冷/热宽温度范围内的人体热调节系统、手指温度仿真以及液冷通风系统传热传质过程,建立了舱外航天服热设计仿真技术平台.通过人体热生理实验对该热设计仿真技术进行了验证. 相似文献
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116.
低RCS飞行器表面弱散射源研究 总被引:3,自引:1,他引:2
飞行器表面不同宽度缝隙、不同高度台阶、不同结构形式对缝(主要包括横向对缝、锯齿对缝两种)等弱散射源对前方雷达截面(RCS)有着比较重要的影响,为了说明控制弱散射源的重要性,介绍了常规飞行器表面结构的缝隙、台阶等弱散射源的分布情况及特点,采用理论方法分析了缝隙的雷达后向散射强度,设计了低RCS载体和实验模型,开展了不同宽度缝隙、不同高度台阶、不同结构形式对缝的RCS实验。结果表明:减小缝隙宽度、台阶高度,采用锯齿缝隙代替直缝隙等方法,是控制隐身飞行器表面电磁缺陷的有效技术途径。 相似文献
117.
Katrin Paulsen Svantje Tauber Nadine Goelz Dana Michaela Simmet Stephanie Engeli Maria Birlem Claudia Dumrese Anissja Karer Sandra Hunziker Josefine Biskup Shalimar Konopasek Durie Suh Eva Hürlimann Christoph Signer Anna Wang Chen Sang Karl-Heinrich Grote Fengyuan Zhuang Oliver Ullrich 《Acta Astronautica》2014
During spaceflight the immune system is one of the most affected systems of the human body. During the SIMBOX (Science in Microgravity Box) mission on Shenzhou-8, we investigated microgravity-associated long-term alterations in macrophageal cells, the most important effector cells of the immune system. We analyzed the effect of long-term microgravity on the cytoskeleton and immunologically relevant surface molecules. Human U937 cells were differentiated into a macrophageal phenotype and exposed to microgravity or 1g on a reference centrifuge on-orbit for 5 days. After on-orbit fixation, the samples were analyzed with immunocytochemical staining and confocal microscopy after landing. The unmanned Shenzhou-8 spacecraft was launched on board a Long March 2F (CZ-2F) rocket from the Jiuquan Satellite Launch Center (JSLC) and landed after a 17-day-mission. We found a severely disturbed actin cytoskeleton, disorganized tubulin and distinctly reduced expression of CD18, CD36 and MHC-II after the 5 days in microgravity. The disturbed cytoskeleton, the loss of surface receptors for bacteria recognition, the activation of T lymphocytes, the loss of an important scavenger receptor and of antigen-presenting molecules could represent a dysfunctional macrophage phenotype. This phenotype in microgravity would be not capable of migrating or recognizing and attacking pathogens, and it would no longer activate the specific immune system, which could be investigated in functional assays. Obviously, the results have to be interpreted with caution as the model system has some limitations and due to numerous technical and biological restrictions (e.g. 23 °C and no CO2 supply during in-flight incubation). All parameter were carefully pre-tested on ground. Therefore, the experiment could be adapted to the experimental conditions available on Shenzhou-8. 相似文献
118.
The fuel regression rate is an important parameter in the design process of the hybrid rocket motor. Additives in the solid fuel may have influences on the fuel regression rate, which will affect the internal ballistics of the motor. A series of firing experiments have been conducted on lab-scale hybrid rocket motors with 98% hydrogen peroxide (H2O2) oxidizer and hydroxyl terminated polybutadiene (HTPB) based fuels in this paper. An innovative fuel regression rate analysis method is established to diminish the errors caused by start and tailing stages in a short time firing test. The effects of the metal Mg, Al, aromatic hydrocarbon anthracene (C14H10), and carbon black (C) on the fuel regression rate are investigated. The fuel regression rate formulas of different fuel components are fitted according to the experiment data. The results indicate that the influence of C14H10 on the fuel regression rate of HTPB is not evident. However, the metal additives in the HTPB fuel can increase the fuel regression rate significantly. 相似文献
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120.
Plume aerodynamic effects of cushion engine in lunar landing 总被引:1,自引:0,他引:1
During the second period of China "Tanyue" Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS (Plume WorkStation) software based on direct simulation Monte Carlo (DSMC) method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed. 相似文献