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421.
K. J. Meech M. F. A’Hearn Y. R. Fernández C. M. Lisse H. A. Weaver N. Biver L. M. Woodney 《Space Science Reviews》2005,117(1-2):297-334
Prior to the selection of the comet 9P/Tempel 1 as the Deep Impact mission target, the comet was not well observed. From 1999 through the present there has been an intensive world-wide observing
campaign designed to obtain mission critical information about the target nucleus, including the nucleus size, albedo, rotation
rate, rotation state, phase function, and the development of the dust and gas coma. The specific observing schemes used to
obtain this information and the resources needed are presented here. The Deep Impact mission is unique in that part of the mission observations will rely on an Earth-based (ground and orbital) suite of complementary
observations of the comet just prior to impact and in the weeks following. While the impact should result in new cometary
activity, the actual physical outcome is uncertain, and the Earth-based observations must allow for a wide range of post-impact
phenomena. A world-wide coordinated effort for these observations is described. 相似文献
422.
423.
Foreign Object Damage to Fan Rotor Blades of Aeroengine Part I: Experimental Study of Bird Impact 总被引:2,自引:0,他引:2
Guan Yupu Zhao Zhenhua Chen Wei Gao Deping 《中国航空学报》2007,20(5):408-414
The conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided. 相似文献
424.
飞机圆弧风挡鸟撞动响应研究 总被引:12,自引:1,他引:12
以全尺寸鸟撞模拟试验测试的撞击力、位移、应变、应变率等参数为基础,研究了圆弧风挡的鸟撞动响应问题对鸟撞问题的性质、载荷计算方法及分析方法等进行了探讨,得出了一些有益的结论。 相似文献
425.
426.
惯性导航系统/双星距离差组合导航算法的可行性研究 总被引:1,自引:0,他引:1
研究由相对于双星的距离差量测与惯性测量系统构成实时的适用于跟踪高动态目标的组合导航系统的可行性。阐述系统工作原理 ,建立了相关的数学模型 ,用拉格朗日乘子法求出了解析解 ,用 Matlab软件验证其结果并作了误差分析。结果表明 :相对于双星的测距差对于惯性测量系统沿双星连线轴向的测量误差算法有十分明显的修正效果 ,但对与双星连线轴正交方向的测量误差 ,其修正能力很差。指出距离差量测本质上是与双星连线轴向相关的一维量测。欲构成对惯性测量三维方向均有修正作用的实时组合导航系统 ,应当在系统中另增加独立的量测量。 相似文献
427.
文章介绍了在Sandia国家实验室所进行的3个精确控制的超高速碰撞试验,使用两种复杂的流体码即多维流体动力学代码CTH和平滑粒子流体动力学代码SPH,对该试验进行数值模拟。该试验用质量为克大小的飞片及球形射弹以大约10km/s的速度撞击薄铝板及钢板(厚度小于1cm)。并分析了碎片云动力学计算预示结果及这些试验中金属板的损坏。 相似文献
428.
429.
Whipple shield is widely used on manned spacecraft, numerical simulation is an important way for obtaining the ballistic limit. The large population of particles and the large space span of Whipple shield simulation model restrict the computational efficiency. A fast numerical approach is presented for Whipple shield ballistic limit analysis. First, the critical penetration analysis of the rear walls is converted into specific impulse analysis delivered by the secondary debris cloud, because the maximum of specific impulse is the main determinant of the penetration. The dual plate simulation model is then converted into single plate model and the population of particles is reduced. Second, based on the isotropic expansion theory of secondary debris cloud, the specific impulse analysis is further converted into particle position and velocity analysis when the stable secondary debris formed. The space span of the simulation model is reduced. An example of Whipple shield ballistic limit analysis is provided for the verification of the fast numerical approach, it shows that this approach can significantly increase the computation efficiency with acceptable accuracy. 相似文献
430.
Cumulative jet formation was regarded aimed at the formation of hypervelocity fragments up to 14 km/s for the investigation of space debris effects on shielding screens. The basic physical problems of jet formation process are analyzed. It is shown that in process of realization of hyper-cumulation conditions for jet formation without complete stagnation point involving formation of the inner zone of constant pressure (dead zone), the flow mass is always greater than slug mass. That opens wide the possibilities for increasing fragment mass in laboratory tests. 相似文献