Directional Solidification Using a Baffle in Microgravity

Numerical simulations were performed to optimize the conditions and parameters for directional solidification of Te-doped GaSb in reduced gravity ranging from 10⁻³ to 10⁻⁵g₀. Our key goal was to quantify the velocity and concentration fields with and without a baffle present in the melt. The effect of the distance of the baffle from the solid–liquid interface was investigated. When the baffle is placed 0.5 cm from the solid–liquid interface, acceleration of 10⁻³g₀ does not cause significant interference with segregation. Furthermore, the flow between the baffle and the interface (low Reynolds number “creeping” flow) does not depend on fluid properties (viscosity).     

热控涂层表面电阻率原位测量方法研究

表面电阻率是航天器热控涂层的重要参数之一。由于航天器所在环境的特殊性,需要对其热控涂层的表面电阻率进行原位测量。文章提出了一种表面电阻率的原位测量方法,即使用导电银胶粘结铜箔电极和样片,并通过弹性钢丝压线把两电极接入测量电路。通过以ITO/Kapton/Al和S781白漆为试验对象的测量,验证了该测量方法的可行性,并对测量结果的影响因素进行了分析。     

水下航行体减阻技术综述

空/水跨介质飞行器经空中飞抵目标水域后高速入水，对目标实施快速打击，具有隐蔽性好、突防能力强等特点。但在水下航行中，固/液界面阻力及绕流流场变化等问题严重影响了航行速度与稳定性。减小航行体表面阻力干扰、流场优化是保障水下高速稳定航行的关键。旨在探讨适用于水下高速航行体的表面减阻与流场优化方法，对表面微结构减阻、超疏水表面减阻、超空泡减阻和微气泡减阻４种最具代表性的固/液界面减阻技术进行论述，分析各种减阻技术的机理与应用可行性，探讨适用于水下高速航行体的减阻技术发展方向。     

High-acceleration mass drivers

After testing an early, simplified mass-driver (35 gravity acceleration) a second, designated MD2, was designed and is now operating. MD2 is of axial geometry, with individually powered drive coils of 13.1 cm diameter. Timing is derived through the interruption of light beams by the moving armature (bucket). Electric power is provided by the resonant discharge of sector capacitor banks through silicon-controlled rectifiers in a two-phase, quadrature circuit. The bucket flies in vacuum, guided by passive dynamic eddy-current magnetic forces, those currents flowing in strip conductors lining the inside of a nonconducting vacuum pipe. The initial length of MD2 is 2.5 m, divided equally into acceleration and deceleration. Nominal acceleration is 5000 m/sec². For routine testing an ohmic bucket is used. Quantitative measurements are obtained with a solid bucket carrying two superconducting coils with a current density of 25 kA/cm². A cryogenic station for cooling the bucket to liquid helium temperature is connected to the vacuum pipe. The test program, now begun, will concentrate on guidance and acceleration forces, measurement of drive shielding losses, and possible couplings of drive forces into modes of oscillation.     

固体火箭发动机质量评判系统研究开发中的非精确推理

介绍了固体火箭发动机质量评判的特点，以带有两种典型伤情缺陷的固体火箭发动机为例，对主观Bayes非精确推理方法在固体火箭发动机质量评判中的应用进行了分析研究，给出了非精确推理框图，并简要介绍了研究推理规划中的充分性度量LS、必要性度量LN和前提的可信度C（E，S），以及计算多种伤情缺陷作用下发动机禁用的后验概率的方法。     

基于透射原理的液面变形测量方法综述

带液体燃料的航天器的液体晃动与运动控制离不开液面变形的精确测量。然而液体的弱反射性、易变形性、强透射性等特点增大了液面变形的测量难度,而传统的固体形貌光测技术并不适用。文章综述了目前应用较广的基于透射的液面变形测量方法,重点对相位偏折法、畸变分析法和光线追踪法的测量原理、灵敏度、适用范围和各自的优缺点进行讨论;并展望液面测量方法的发展方向和趋势。     

多目标多光谱高温仪的研制

根据固体火箭发动机羽焰特征研制了多目标多光谱高温仪。文中介绍了多光谱测温技术及测温仪系统构成。该系统可同时测量羽焰6个目标点的温度,每个目标点均有8个工作波长,可实现对发动机试验时羽焰流场轴向和环向多目标的温度动态测量。     

PHYSIOLAB: a new laboratory for the study of the cardio-vascular system

On the basis of the experience gained during the previous french-russian missions on board MIR about the adaptation processes of the cardio-vascular system, a new laboratory has been designed. The objective of this “PHYSIOLAB” is to have a better understanding of the mechanisms underlying the changes in the cardio-vascular system, with a special emphasis on the phenomenon of cardio-vascular deconditioning after landing.

Beyond these scientific objectives, it is also intended to use PHYSIOLAB to help in the medical monitoring on-board MIR, during functional tests such as LBNP.

PHYSIOLAB will be set up in MIR by the French cosmonaut during the next french-russian CASSIOPEE mission in 1996. Its architecture is based on a central unit, which controls the experimental protocols, records the results and provides an interface for transmission to the ground via telemetry. Different specific modules are used for the acquisition of various physiological parameters.

This PHYSIOLAB under development for the CASSIOPEE mission should evolve towards a more ambitious laboratory, whose definition would take into account the results obtained with the first version of PHYSIOLAB. This “second generation” laboratory should be developed in the frame of wide international cooperation.     

遥感系列卫星在轨微振动测量与分析

在遥感系列卫星上装载了微振动环境测量系统并进行了在轨微振动环境测量。文章介绍了4颗遥感卫星的在轨微振动环境参数获取与分析。结果表明:星上各活动部件中主要的扰振源为反作用轮和辐射计/散射计转动机构;卫星稳定运行时的最大微振动量级约为57 mg,传递到光学敏感设备衰减度约为15%。     

Determination of characteristic frequencies of elastic oscillations of the <Emphasis Type="Italic">International Space Station</Emphasis> construction

The results of investigating free oscillations of the International Space Station construction appearing during spacecraft docking and undocking are described. The study is carried out using the measurement data of the low-frequency MAMS accelerometer. Several intervals of measurements performed in 2005 and 2006 were chosen to be studied. For chosen intervals, only the data intervals corresponding to the process of free attenuation of the oscillations construction elements were analyzed. Characteristic frequencies of elastic oscillations of the station construction and attenuation coefficients corresponding to them are found. The comparative analysis of the results obtained for various docking ports (nodes) is carried out. The described study is performed as a part of the technical experiment “The ISS Environment” carried out onboard the station in accordance with the Russian program of scientific and engineering experiments.     

Mass transfer interaction of moving particles in a reactive dispersive system

Mass transfer from a system of particles moving linearly in a viscous fluid is considered. A chemical reaction on the particle surfaces is taken into account. The analysis is based on the investigation of concentration and velocity fields in a particle wake and of the distortion of these fields due to particles interaction. The values of both local and average Sherwood numbers are calculated.The results obtained are applied to the system of drops and solid spherical particles moving in line along the axis of uniform Stokes flow. It is shown, that if the distance 1 between the particles satisfies the condition (a is the sphere radius and P is the Peclet number) then the total diffusion flux to the surface of kth sphere is as follows

Full-size image (1K)

. Here k is the particle number along the stream (for the leading particle k = 1), I₁ is the diffusion flux to the leading particle: n = 1 for drops, n = 2 for solid particles.     

液氮贮箱自增压实验与数值仿真

为研究低温推进剂在常温下的自增压过程，设计了以液氮为模拟介质可视化低温玻璃贮箱自增压实验系统，研究了自增压过程压力和温度的变化规律及体积充填率对压力和温度变化的影响。实验结果表明：气枕区和液体区存在显著的轴向温度分层，液体区温度的上升速率低于压力引起饱和温度的上升速率。压力上升分为有典型意义的三段：初始段、过渡段和稳定段，稳定段的压力上升速率随体积充填率增加而增加。液体区的对流运动在自增压过程受到抑制，气液界面逐渐进入准静止状态。并以实验测得温度作为边界条件，采用流体体积（VOF）模型对整个自增压过程进行了175 s的数值仿真。仿真得到的压力曲线变化规律与实验结果基本一致，稳定段的压力上升速率是实验值的1.58倍。本文得到的自增压物理参数变化规律，为低温推进剂的贮存和贮箱的热防护设计提供参考。     

一种便携式高精度超声流量仪

研究一种超声波传播方向平行于液体流动方向的流量管和以此为基础的超声流量仪。针对流量系统的新型流量管结构推导两种流量算法并进行误差分析,其中一种算法可以减小由声速变化引起的误差,从而提高系统的测量稳定性,也为流量管的改进方向提供了思路。使用测显比曲线修正管道中流体流速分布不均匀的影响以提升测量准确性,试验证明,在测量范围内,系统测量的平均示值误差不超过0.2%。     

碳纤维复合材料贮箱内压和低温承载行为研究

碳纤维增强聚合物复合材料具有轻质高强的优异特性,是液氢液氧燃料贮箱的理想材料。然而液氢液氧燃料贮箱在服役时要承受极低温度载荷,复合材料贮箱箱体的低温结构可靠性尚未可知。开展了碳纤维/环氧复合材料缠绕贮箱结构在温度和内压载荷下的变形及损伤研究,分别进行了常温/低温抗渗漏测试,结合应变测量、声发射监测、氦质谱检漏等方法分别研究了内压以及低温工况对复合材料贮箱的应变分布及损伤泄漏状态影响机制。研究结果表明,封头与圆筒区域交界处易产生应变集中,低温载荷导致复合材料局部小幅度基体损伤及纤维/基体界面脱粘,但并未影响贮箱箱体承压性能和气密性。本研究可为未来大型航天器减质设计提供参考。     

Uncontrolled Attitude Motion of the Foton-12 Satellite and Quasi-Steady Microaccelerations onboard It

The results of determination of the uncontrolled attitude motion of the Foton-12 satellite (placed in orbit on September 9, 1999, terminated its flight on September 24, 1999) are presented. The determination was carried out by the onboard measurement data of the Earth's magnetic field strength vector. Intervals with a duration of several hours were selected from data covering almost the entire flight. On each such interval the data were processed simultaneously using the least squares method by integrating the satellite's equations of motion with respect to the center of mass. The initial conditions of motion and the parameters of the mathematical model employed were estimated in processing. The results obtained provided for a complete representation of the satellite's motion during the flight. This motion, beginning with a small angular velocity, gradually sped up. The growth of the component of the angular velocity with respect to the longitudinal axis of the satellite was particularly strong. During the first several days of the flight this component increased virtually after every passage through the orbit's perigee. As the satellite's angular velocity increased, its motion became more and more similar to the regular Euler precession of an axisymmetric rigid body. In the last several days of flight the satellite's angular velocity with respect to its longitudinal axis was about 1 deg/s and the projection of the angular velocity onto the plane perpendicular to this axis had a magnitude of approximately 0.15 deg/s. The deviation of the longitudinal axis from the normal to the orbit plane did not exceed 60°. The knowledge of the attitude motion of the satellite allowed us to determine the quasi-steady microacceleration component onboard it at the locations of the technological and scientific equipment.     

姿控发动机试验阀门电流信号采集系统设计

介绍了液体火箭姿控发动机阀门电流信号采集系统的设计要点、研制方法与主要开发过程。较详细阐述了高速数据采集系统应用软件开发及系统集成后的调试方法。该采集系统实现了多路液体火箭姿控发动机试车阀门电流信号的数字化测量。