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Yonglong Zhang Junfeng Li Xiangyuan Zeng 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(10):3328-3342
Asteroids are coming to be a popular topic in the areas of astrophysical studies and deep space exploration recently. However, surface dynamics of asteroids is still a difficult problem. This paper aims at the motion analysis of surface particles for different asteroids. The dynamical analysis method of particles’ movement is given for three parts: global motion trend, local motion trend and static analysis. A dimensionless parameter ζ is defined to distinguish the predominant term to determine the distribution of effective potential. Three kinds of common asteroids: spheroidal asteroid, spindle-shaped asteroid and dumbbell-shaped asteroid are all discussed for those three parts with different parameter ζ. The motion trend of particles on the surface of each kind of asteroid is given. The static analysis of surface particles for different asteroids is also illustrated. Based on them, some common rules for different shaped asteroids are revealed. This paper could not only provide a reference for asteroid exploration missions but also be meaningful for the research of morphologic evolution of asteroids. 相似文献
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To date, NASA's “Near Earth Object Program” has discovered over 5500 comets and asteroids on trajectories that bring them within “the neighborhood” of Earth's orbit. Nearly 1000 of these objects are classified as “potentially hazardous,” passing within 0.05 astronomical units of Earth's orbit. Discovery rates of such threatening bodies increase each year. Given this multitude of threats, in addition to evidence that the planet has absorbed many impacts over its history, it is reasonable to assume that another object will strike the Earth at some point in the future. Consequently, researchers have studied and proposed several mitigation techniques for such an occurrence. This study seeks to determine how effectively the attachment of a tether and ballast mass would divert the trajectory of such threatening objects. Specifically, the study analyzes the effects over time of such a system on objects of varying orbital semimajor axis and eccentricity, using various tether lengths and ballast masses. It was determined that the technique is most effective for NEOs with high eccentricity and small semimajor axis, and that system performance increases as tether length and ballast mass increase. 相似文献
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载人小行星探测任务总体方案研究 总被引:1,自引:1,他引:0
设计了在近地轨道组装具有分组单元结构的载人深空飞船,包括核热推进单元、燃料储箱与供给单元、主动防辐射单元、人工重力单元、深空居住舱与多任务乘员舱等,给出了各个单元的尺寸与质量参数,并对主要单元的具体组成、功能和技术特点进行了分析。在此基础上,本文以编号4660的Nereus小行星为探测目标,设计了两脉冲转移初始轨道,并进行了轨道优化,得到了发射窗口和最优转移轨道。仿真结果表明,给出的最优两脉冲转移轨道单次施加脉冲在5km/s以内,单程转移时间在160d以内,能够满足未来能量较小的载人小行星探测任务。 相似文献
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三级旋流器的设计及其流场模拟 总被引:6,自引:1,他引:5
利用UG软件建立三级旋流器模型燃烧室的几何模型,采用四面体非结构网格划分方法,生成网格计算模型,应用Realizable k-ε湍流模型对该模型燃烧室的冷态流场进行数值模拟。研究结果表明:与旋流器其它参数相比,各级旋流器之间的流量分配对三级旋流器的流场特性(如回流区范围和中心速度分布)有较大的影响。深化了对三级旋流器各种设计参数的认识,有助于实现三级旋流器的进一步优化设计。 相似文献
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三旋流燃烧室燃烧特性试验 总被引:1,自引:1,他引:0
针对舰船用燃气轮机低污染排放要求,试验研究了一种三旋流贫预混燃烧室燃烧性能。结果表明:三旋流燃烧室内、中旋流角决定了点火成功与否,而外旋流角仅对点火、熄火极限有影响。采用内、中、外旋流角依次增加10°,旋流数依次增加33.3%、25.0%的组合方式有较好的点火、熄火性能;贫油点火油气比最低为0.05236,高于非预混燃烧室的一般标准,熄火油气比最低为0.00478,低于一般要求;燃烧室出口温度分布系数为0.2279,完全满足设计要求; NOx排放指数为2.62g/kg,低污染优势明显。CO排放指数较高,为35.4g/kg,导致燃烧效率略低,仅为0.9847。 相似文献