单航天器激光天文动力学空间计划(ASTROD Ⅰ)是激光天文动力学空间计划(ASTROD:Astrodynamical Space Test of Relativity using Optical Devices)的第一步。ASTROD Ⅰ空间计划概念是使用在太阳轨道上的一个无拖曳航天器和地面站以双向...单航天器激光天文动力学空间计划(ASTROD Ⅰ)是激光天文动力学空间计划(ASTROD:Astrodynamical Space Test of Relativity using Optical Devices)的第一步。ASTROD Ⅰ空间计划概念是使用在太阳轨道上的一个无拖曳航天器和地面站以双向激光干涉跟踪和脉冲计时测距的方法,精确地探讨天文动力学,检测相对论与时空基本定律,改进探测引力波的灵敏度以及更准确地测定太阳、行星和小行星的参数。ASTROD Ⅰ在天文动力学方面,和检测相对论与时空基本定律方面,精确度将比现在提高3个数量级;在测定太阳、行星和小行星参数方面,精确度将比现在提高1-3个数量级。ASTROD Ⅰ对引力波的探测灵敏度,可以比现在的射电波追踪航天器的引力波探测灵敏度稍作提高。航天器可由长征四号乙(CZ-4B)运载火箭发射,从低绕地转移轨道直接进入绕日轨道,经由金星引力助推两次,于发射后三百多天抵达太阳对面从事相对论Shapiro效应测量。乐观的发射日期可在2012年、2013年或2015年。单航天器激光天文动力学空间计划的推动,可以对重要关键技术如无拖曳航天、弱光锁相、空间光通讯等的发展起到带头作用。本计划的第一阶段预研究,主要由中国和欧洲的德国、英国和法国科学家合作进行。本文综述ASTROD Ⅰ的科学目标和基本方案,作为第一阶段预研究分项讨论的基础。展开更多
This paper presents the setup and performance of a drop tower experiment which investigates the behavior of liquid during self-driven capillary transport between two parallel perforated plates under microgravity. With...This paper presents the setup and performance of a drop tower experiment which investigates the behavior of liquid during self-driven capillary transport between two parallel perforated plates under microgravity. With the onset ofmicrogravity the liquid rises between the two parallel plates as a result of capillary pressure. Eight different sets of plates are tested in this study and the free surface height and the volume of transported liquid is subsequently analyzed. The plate sets differ in geometric properties of their perforations, distance, and width. In each set the perforations of both plates are identical and have a diameter of a few millimeters. The capillary rise velocity is influenced by the perforation diameter and the area porosity of the plates. As could be expected, the capillary transport capability increases with decreasing plate porosity.展开更多
In this paper the theoretical model is built for ZEpHyR(ZARM Experimental Hybrid Rocket) main engine which is being developed at ZARM institute,Bremen,Germany.The theoretical model is used to estimate the temperature ...In this paper the theoretical model is built for ZEpHyR(ZARM Experimental Hybrid Rocket) main engine which is being developed at ZARM institute,Bremen,Germany.The theoretical model is used to estimate the temperature of exhaust gas.The Conjugate Gradient Method(CGM) with Adjoint Problem for Function Estimation iterative technique is used to solve the Inverse Heat Conduction Problem(IHCP) to estimate the heat flux and internal wall temperature at the throat section of the nozzle.Bartz equation is used to calculate the convective heat transfer coefficient.The exhaust gas temperature is determined using the estimated heat flux,the wall temperature at internal surface of nozzle and the heat transfer coefficient.The accuracy of CGM iterative scheme to solve the IHCP is also investigated and its results are presented.展开更多
It is difficult and high-cost to detect flame fronts by laser-sheet diagnostics under microgravity （μg）, thus image processing is critical to obtain valuable information from the raw data. In the present study, pre...It is difficult and high-cost to detect flame fronts by laser-sheet diagnostics under microgravity （μg）, thus image processing is critical to obtain valuable information from the raw data. In the present study, premixed V-flames were detected under μg by OH planar laser-induced fluorescence （PLIF） and an effective method based on active contour model （ACM） is presented for automatic detecting and tracking flame fronts in the PLIF images. ACM can effectively detect the flame front in the images with low contrast and noises. Compared with other methods of flame front detection, the advantage of this method is that the image smoothing and image enhancement are not necessary for the correct detection of flame fronts in raw PLIF images.展开更多
文摘单航天器激光天文动力学空间计划(ASTROD Ⅰ)是激光天文动力学空间计划(ASTROD:Astrodynamical Space Test of Relativity using Optical Devices)的第一步。ASTROD Ⅰ空间计划概念是使用在太阳轨道上的一个无拖曳航天器和地面站以双向激光干涉跟踪和脉冲计时测距的方法,精确地探讨天文动力学,检测相对论与时空基本定律,改进探测引力波的灵敏度以及更准确地测定太阳、行星和小行星的参数。ASTROD Ⅰ在天文动力学方面,和检测相对论与时空基本定律方面,精确度将比现在提高3个数量级;在测定太阳、行星和小行星参数方面,精确度将比现在提高1-3个数量级。ASTROD Ⅰ对引力波的探测灵敏度,可以比现在的射电波追踪航天器的引力波探测灵敏度稍作提高。航天器可由长征四号乙(CZ-4B)运载火箭发射,从低绕地转移轨道直接进入绕日轨道,经由金星引力助推两次,于发射后三百多天抵达太阳对面从事相对论Shapiro效应测量。乐观的发射日期可在2012年、2013年或2015年。单航天器激光天文动力学空间计划的推动,可以对重要关键技术如无拖曳航天、弱光锁相、空间光通讯等的发展起到带头作用。本计划的第一阶段预研究,主要由中国和欧洲的德国、英国和法国科学家合作进行。本文综述ASTROD Ⅰ的科学目标和基本方案,作为第一阶段预研究分项讨论的基础。
文摘This paper presents the setup and performance of a drop tower experiment which investigates the behavior of liquid during self-driven capillary transport between two parallel perforated plates under microgravity. With the onset ofmicrogravity the liquid rises between the two parallel plates as a result of capillary pressure. Eight different sets of plates are tested in this study and the free surface height and the volume of transported liquid is subsequently analyzed. The plate sets differ in geometric properties of their perforations, distance, and width. In each set the perforations of both plates are identical and have a diameter of a few millimeters. The capillary rise velocity is influenced by the perforation diameter and the area porosity of the plates. As could be expected, the capillary transport capability increases with decreasing plate porosity.
文摘In this paper the theoretical model is built for ZEpHyR(ZARM Experimental Hybrid Rocket) main engine which is being developed at ZARM institute,Bremen,Germany.The theoretical model is used to estimate the temperature of exhaust gas.The Conjugate Gradient Method(CGM) with Adjoint Problem for Function Estimation iterative technique is used to solve the Inverse Heat Conduction Problem(IHCP) to estimate the heat flux and internal wall temperature at the throat section of the nozzle.Bartz equation is used to calculate the convective heat transfer coefficient.The exhaust gas temperature is determined using the estimated heat flux,the wall temperature at internal surface of nozzle and the heat transfer coefficient.The accuracy of CGM iterative scheme to solve the IHCP is also investigated and its results are presented.
基金This work was partially supported by Natural Science Foundation of China under Grant No. 50276061.
文摘It is difficult and high-cost to detect flame fronts by laser-sheet diagnostics under microgravity （μg）, thus image processing is critical to obtain valuable information from the raw data. In the present study, premixed V-flames were detected under μg by OH planar laser-induced fluorescence （PLIF） and an effective method based on active contour model （ACM） is presented for automatic detecting and tracking flame fronts in the PLIF images. ACM can effectively detect the flame front in the images with low contrast and noises. Compared with other methods of flame front detection, the advantage of this method is that the image smoothing and image enhancement are not necessary for the correct detection of flame fronts in raw PLIF images.
