嫦娥五号探测器GNC系统设计

为实现我国首次月球样品无人采样返回任务,设计了嫦娥五号(Chang’E 5)探测器制导、导航与控制(GNC)系统.根据任务要求和探测器特点,GNC系统设计分为轨道器GNC子系统、返回器GNC子系统和着上组合体GNC子系统.给出了嫦娥五号探测器GNC系统的架构设计、工作模式以及在轨飞行结果.结果表明,GNC系统设计正确,成功完成了动力下降、起飞上升、交会对接、返回再入等关键动作,实现了月球表面起飞上升、月球轨道交会对接以及携带月壤以近第二宇宙速度二次再入返回的三项首次任务,各项功能性能满足任务要求.     

一种可实现的离散时间最优末制导律

提出了一种可实现的离散时间最优末制导律,该制导律在导弹导引头获取的目标加速度信息的基础上,以时间最优为设计指标,可动态调整最优控制量,能够适应目标末端机动,并采用变周期算法以提高收敛速度。仿真结果表明,该制导律能够满足给定脱靶量要求,成功拦截目标。     

空中乘务专业建设与发展的思考

空中乘务是国家教育部学科编制目录中增加的新兴专业。空乘专业人才培养的定位,专业课程的设置,专业教材的编写等均没有可参照和借鉴的样本。本文就如何运用科学发展的理念和手段,解决空乘专业建设过程中存在的问题和困难,谈一些思考和建议。     

Chang'E-1 Lunar Mission:An Overview and Primary Science Results

Chang'E-1 is the first lunar mission in China, which was successfully launched on Oct. 24th, 2007. It was guided to crash on the Moon on March 1, 2009, at 52.36oE, 1.50oS, in the north of Mare Fecunditatis. The total mission lasted 495 days, exceeding the designed life-span about four months. 1.37 Terabytes raw data was received from Chang'E-1. It was then processed into 4 Terabytes science data at different levels. A series of science results have been achieved by analyzing and applicating these data, especially "global image of the Moon of China's first lunar exploration mission'. Four scientific goals of Chang'E-1 have been achieved. It provides abundant materials for the research of lunar sciences and cosmochemistry. Meanwhile these results will serve for China's future lunar missions.      

Study of seasonal variation of winds in upper stratosphere over Hyderabad

A predictability of the stratospheric zonal winds above 38 km during the turnaround is an essential parameter for planning of the high-altitude scientific balloon flights. This information is more relevant in the case of Hyderabad balloon facility which is closer to equator and has much more unstable wind reversal patterns which appears to have changed enormously during the last decade probably in correlation with the global warming. With a majority of our flights reaching the altitudes of 38–42 km and the requirement of long float durations, a prior knowledge of wind pattern during the summer and winter turnaround seasons is highly desirable. Furthermore, the flight operation corridor for balloon flights from Hyderabad is limited to 400 km and though in the west direction there are flat lands, in all other three directions, the landscape is dotted by water bodies, reserve forests and hilly terrain, and therefore need of such a data is essential. In order to establish the climatology of the stratospheric winds and study their inter-annual variability over Hyderabad for the turnaround periods, we have made a detailed analysis of the United Kingdom Meteorological office data between 2000 and 2007, to derive average wind parameters (magnitude, direction) at different ceiling altitudes above 38 km. These results can be used only as general trend of stratospheric wind and should not be the limitation of the UKMO Data.     

便携式多功能校准仪在专用测试设备现场校准中的应用CSCD

航天工程专用测试设备具有系统复杂、参数多、不易移动的特点,常用校准方法复杂度高、效率低、成本高。为保证航天工程科研生产的顺利进行,专用测试设备的准确可靠及可溯源性越来越受到研制、生产和使用方的重视,并介绍了五种常用的专用测试设备校准方法。并针对目前常用校准方法的不足,提出将便携式多功能校准仪应用在专用测试设备现场校准的新方法,给出了不确定度分析。     

星载主动遥感气溶胶-云参数技术需求与进展

面对越来越迫切的气象和气候预测及大气环境监测需求,利用主动星载仪器在全球范围内探测云和气溶胶参数成为快速发展的研究领域。相比被动遥感仪器,主动仪器可以获取云和气溶胶参数的垂直分布信息,这将在天气气候模式的改进方面发挥重要作用。通过云和气溶胶遥感需求分析,从雷达数据应用角度,首先介绍了数值模式对云和气溶胶的科学参数需求和定量需求,进一步分析了云和气溶胶联合观测的需求,以及星载微波激光雷达的探测特点;然后对国内外正在规划的星载云和气溶胶微波激光雷达探测任务进行了综述,包括仪器指标和数据产品设计;最后展望这一领域的应用前景。     

LES of film cooling for different jet fluids

The present paper investigates the impact of the velocity and density ratio on the turbulent mixing process in gas turbine blade film cooling.A cooling fluid is injected from an inclined pipe at α=30° into a turbulent boundary layer profile at a freestream Reynolds number of Re∞=400000.This jet-in-a-crossflow(JICF) problem is investigated using large-eddy simulations(LES).The governing equations comprise the Navier-Stokes equations plus additional transport equations for several species to simulate a non-reacting gas mixture.A variation of the density ratio is simulated by the heat-mass transfer analogy,i.e.,gases of different density are effused into an an air crossflow at a constant temperature.An efficient large-eddy simulation method for low subsonic flows based on an implicit dual time-stepping scheme combined with low Mach number preconditioning is applied.The numerical results and experimental velocity data measured using two-component particle-image velocimetry (PIV) are in excellent agreement.The results show the dynamics of the flow field in the vicinity of the jet hole,i.e.,the recirculation region and the inclination of the shear layers,to be mainly determined by the velocity ratio.However,evaluating the cooling efficiency downstream of the jet hole the mass flux ratio proves to be the dominant similarity parameter,i.e.,the density ratio between the fluids and the velocity ratio have to be considered.      

Non-destructive Evaluation of Composite Pressure Vessel by Using FBG Sensors

In recent years, advanced composite structures are used extensively in many industries such as aerospace, aircraft, automobile, pipeline and civil engineering. Reliability and safety are crucial requirements posed by them to the advanced composite structures be- cause of their harsh working conditions. Therefore, as a very important measure, structural health monitoring (SHM) in-service is defi- nitely demanded for ensuring their safe working in-situ. In this paper, fiber Bragg grating (FBG) sensors are surface-mounted on the hoop and in the axial directions of a FRP pressure vessel to monitor the strain status during its pressurization. The experimental results show that the FBG sensors could be used to monitor the strain development and determine the ultimate failure strain of the composite pressure vessel.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.