2016 Vol. 36, No. 4

Display Method:
Space Growth of Bismuth Telluride Based Thermoelectric Semiconductive Crystals
CHEN Yan, BAO Yefeng, LI Xiaoya, ZHOU Yanfei, CHEN Lidong
2016, 36(4): 413-419. doi: 10.11728/cjss2016.04.413
Bismuth telluride based thermoelectric semiconductors are high performance thermoelectric materials in the low temperature range (about 300℃), which have important applications in thermoelectric cooling and precise temperature control of electronic devices, and have broad application prospects in thermoelectric generation through industrial waste heat recovery. Bismuth tellurides are mainly produced with zone melting method, and their ZT value is around 0.8. The ZT value needs to be further improved as bismuth telluride is applied to commercial domain. Although alloying and doping are effective methods to improve the ZT value, they will make the chemical composition of bismuth tellurides become more complicated. The inherent problems of zone melting method, buoyancy force convection and wall effect, are revealed under gravity, and will make the fluctuation of chemical composition and thermoelectric properties become larger. Microgravity in space may eliminate the buoyancy force convection and wall effect, and can improve the chemical homogeneity and thermoelectric properties of bismuth tellurides. In this paper the development of zone melting of bismuth tellurides under microgravity is reviewed, and the following researched on the zone melting of bismuth telluride that will be carried on the Shijian-10 satellite and the Tiangong-2 space station is prospected.
Bandgap Tuning of InSb by Chemical Doping
ZHANG Xingwang, WU Jinliang, YIN Zhigang
2016, 36(4): 420-423. doi: 10.11728/cjss2016.04.420
Abstract(1159) PDF 601KB(803)
The growth of InAsSb crystal by using the Bridgeman method is reported, and the structural, optical and electric characterizations of the crystal are depicted. It is found that the (111) X-ray diffraction peak exhibits a shift towards the higher-angle side, accompanied by a notable broadening of the peak width. According to the Vegard law, the As doping concentration of the sample can be calculated, which agrees well with the result obtained by energy-dispersive X-ray spectroscopy. Moreover, the substitution of Sb by As results in an observable increase of the background carrier concentration of the material system. The As doping can also severely influence the optical properties of InSb, leading to a distinct reduction of the bandgap as revealed by the measurements of Fourier transform infrared transmission spectra. The bandgap derived by fitting the (αd)2- plot is in agreement with the value obtained by the Woolley-Warner relationship. Our results show that As doping is a feasible way for the realization of long-wavelength infrared InSb-based detectors.
Properties of Bulk Antimonide-based Magnetic Semiconductors
YIN Zhigang, WU Jinliang, ZHANG Xingwang
2016, 36(4): 424-427. doi: 10.11728/cjss2016.04.424
By using the Bridgeman method, the growth of GaMnSb bulk materials and their structural, magnetic and electric characterizations are reported. Room-temperature ferromagnetic signals were observed at the Mn-rich regions, whereas the Mn-deficient areas exhibit diamagnetism. The saturated magnetization in the Mn-rich areas is merely 0.013μB per Mn atom, which is far lower than the theoretical value. Electric measurements show that these two regions almost have identical hole concentrations, which indicates that the difference in the magnetic behaviors is not correlated with the carrier concentration. The characterizations by energy-dispersive X-ray spectroscopy demonstrate that the distribution of Mn atoms is more uniform in the Mn-poor regions than that in the Mn-rich regions. Moreover, the X-ray diffraction measurements reveal the appearance of MnSb impurity phase in the Mn-rich regions. All these results show that the ferromagnetism observed here is extrinsic.
Ground Experiment of CsI(Eu) Single Crystal Space Growth
LIU Jinfeng, XU Guisheng, ZHU Xiu, TIAN Yanfeng
2016, 36(4): 428-431. doi: 10.11728/cjss2016.04.428
Single crystals play quite an important role in material applications. In the process of single crystals growth, ingredients of crystals vary along its growth orientation because of the segregation. Consequently, uniformity of the crystal may be affected, which add to the disadvantage of its application. In order to study the influence of microgravity on the segregation of multicomponent crystal, the crystal growth through the platform of Tiangong-2 is planned. Considering the growth properties and the condition of Tiangong-2, Eu2+ doped CsI is chosen as the study object. The inner structure of quartz ampoule is designed, which passes the vibration experiment successfully. Moreover, the high quality single crystal is grown in the laboratory, and the concentration segregation is found obviously in the specimen.
Ground-based Experiments of Low Temperature Solution Crystal Growth in Space
SONG Youting, CHEN Wanchun
2016, 36(4): 432-437. doi: 10.11728/cjss2016.04.432
To investigate the microgravity effect of low temperature solution crystal growth in space, an apparatus used for crystal growth of low temperature solution has been developed. In the apparatus the hydrophobic polytetrafluoroethylene membrane is first used to seal a growth container by employing the water-repellent and ventilate characteristics of the membrane. When a solvent (water) leaves the growth container by evaporation, and then is absorbed by an adsorbent at the outer of the container, the crystal growth can be continuously carried out. A series of growth experiments on the ground have been performed utilizing this apparatus, and a number of α-LiIO3 crystals with large size and good quality have been obtained. It has been confirmed that the tightness of the membrane to seal a crystallizer and the evaporation capacity of a solvent through it can meet the requirement of low temperature solution crystal growth. A good foundation has been built for future crystal growth experiment in space.
Recent Advances on Preparation and Non-linear Optical Response of High-performance Nanocomposite Films
HUA Zile, GU Jinlou, CUI Fangming, SHI Jianlin
2016, 36(4): 438-444. doi: 10.11728/cjss2016.04.438
Researches on mesoporous materials have got great progress in the past decade. Recent advances of our group on the study of preparation and non-linear optical response of high-performance mesoporous-based nanocomposite films are summarized. Special attentions are focused on new methodology design for the highly efficient and homogeneous incorporation of the metal or semiconductor nanoparticles in the pore channels of mesoporous thin films. These new methodologies include like-dissolves-like, ion-exchange, electroless deposition, electric deposition, deposition-precipitation and surface-modification protocols with mesoporous silica or titania matrix. Afterwards, the non-linear optical responses of the resultant nanocomposite films and the thermally post-treated ones in the presence or absence of magnetic field are analyzed. Finally, some perspectives for the further development of mesoporous nanocomposites films are also discussed.
Solidification of AlCuMgZn Single Crystal in Space
LUO Xinghong, FENG Shaobo, LI Yang
2016, 36(4): 445-449. doi: 10.11728/cjss2016.04.445
Gravity plays an important role in alloy solidification process and defect formation. However, it is difficult to reveal the effects of gravity and study the mechanisms through traditional ground-based solidification experiments. Under microgravity conditions, the effects of gravity on molten melt and solidification process will be significantly diminished. Therefore, in order to explore the role of gravity in dendrite growth process and solute segregation as well as solidification defect formation, by using the microgravity environment in space, and combining with ground-based comparison experiments, the dendritic morphologies, characteristics sizes as well as solute segregation and defect formation under normal gravity and microgravity of AlCuMgZn single crystal alloy are planning to be comparatively investigated during Tiangong-2 mission. In this paper, the progress of the project, such as the research contents, sample and ampoule design, space experimental scheme and main ground-based tests and results are introduced.
Microstructure Evolution of Directionally Solidified Al-3.4%Bi Alloy
JIANG Hongxiang, SUN Qian, ZHAO Jiuzhou, YANG Zhizeng
2016, 36(4): 450-454. doi: 10.11728/cjss2016.04.450
Directional solidification experiments are carried out with Al-3.4%Bi alloy and the microstructure evolution mechanism is investigated. The results demonstrate that a solute-rich layer forms in front of the solidification interface and the liquid-liquid decomposition occurs at the same region. When the alloy is solidified at a relatively low velocity, the size distribution of the minority phase particles shows two peaks. When the alloy is solidified at a high velocity so that the minority phase droplets of all sizes in front of the solidification interface migrate to the solidification interface, the size distribution of the minority phase particles shows only one peak.
Influence of Microgravity and Electromagnetic Field on the Solidification of Metallic Alloys
WANG Xiaodong
2016, 36(4): 455-458. doi: 10.11728/cjss2016.04.455
Solidification or crystal growth of metallic alloys is crucially determined by flow, heat and mass transfer, whilst the external imposed fields like electromagnetic field or gravitational environment can significantly influence these transfer processes. In this paper, two experiments are briefly presented to exhibit above influence on the microstructure evolution of metallic alloys, particularly on the Columnar-Equiaxed Transition (CET). Firstly, a sound rocket-based experiment demonstrates the effect of microgravity by comparison with that of ground-based experiment, and the quite different microstructure reveals that the natural convection plays an essential role in the solidification. Secondly, a quasi-two-dimensional solidifying experimental benchmark is presented to exhibit the natural and forced convection on the micro/macro segregation of the metallic alloys. The natural convection has been observed through the evolution of temperature field measured in real time, and this experiment exhibit the solute segregation naturally formed in the liquid and mushy zones. The forced convection driven by a traveling electromagnetic field interferes with solute segregation directly. Lastly, their influence mechanisms are analyzed and perspective of China's research strategy for material science in space is addressed.
Ground Experimental Study of the Colloidal Material Box aboard SJ-10 Satellite
LI Weibin, LAN Ding, WANG Yuren
2016, 36(4): 459-463. doi: 10.11728/cjss2016.04.459
The colloidal material box is one of the important subsystems of SJ-10 satellite, which is used for studying the self-assembly of the colloidal spheres in space. The ground experiment is an important way for exploring space experimental conditions. This paper introduces the ground experiments around the colloidal material box. First of all, a hydrophobic/hydrophilic confined substrate is prepared, and rule of the apparent contact angle under evaporation is analyzed. The particle deposition behavior of the confined colloidal droplet in evaporation process is investigated by using an in-situ optical observation system, and it is found that the pattern formation process is controlled by three dynamics behaviors. The self-excited oscillation mechanism of droplets pinned on a confined substrate is also studied by drop tower and high-speed photography technology, which shows that the two stages of the oscillation process have different characteristics. The ground experimental results offer important assurance for in-orbit experiment conditions and contrast of space and ground experiments, and are meaningful for engineering parameters setting and experiment conditions matching.
Simulation and Ground Experiment Investigation of Material Experimental Furnace in Space
TAO Ye, YANG Liping, ZHONG Qiu, LUO Caiyun, XU Zijun
2016, 36(4): 464-468. doi: 10.11728/cjss2016.04.464
The temperature distribution of material experimental furnace is critical to materials preparation and the safety operation of furnace in space. For example, it directly affect the growth process of crystals. On the basis of reasonable simplification of the physical model of material experimental furnace that will be carried by Tiangong-2, a 3D heat transfer numerical model is established, and thermophysical parameters of the furnace material are measured. Using the heat transfer model, the thermophysical parameters is simulated. The simulation results coincide well with the ground experimental results. The influence of specimen thermophysical parameters on the furnace and specimen temperature distribution is analyzed by simulation. Moreover, an optimal design is carried out for heat insulation parts of the furnace, and surface temperature distribution of the furnace is predicted. The inadequacy of temperature measuring point can be compensated by the simulating calculation. The simulation can help to obtain the specimen temperature distribution, and can provide foundation for optimal design of the furnace heat insulation and its safe operation.
Current Status and Future Prospects on Microgravity Coal Combustion
ZHANG Hai, CHEN Jialun, ZHANG Pei, LIU Bing, ZUO Cheng, QIAO Yu
2016, 36(4): 469-475. doi: 10.11728/cjss2016.04.469
Microgravity environment minimizes the buoyancy effect that the coal particles suffer during the combustion under normal gravity, and thus provides an ideal environment to discover new phenomena and obtain more accurate data. The results are useful to explore the basic combustion principles and the strength of the buoyancy effect on coal combustion, and to validate and develop coal combustion models for the ground coal utilization. The characteristics of coal ignition and combustion are the theoretical foundation for highly efficient and clean utilization of coal resources. This paper reviews the latest status and comments on the future prospects of the researches on microgravity coal combustion. The experimental system carried on SJ-10 satellite is also briefly introduced.
Linear Stability Analysis of Thermocapillary Convection in Annular Pools
CHEN Qisheng, HE Meng, HU Kaixin
2016, 36(4): 476-480. doi: 10.11728/cjss2016.04.476
Abstract(926) PDF 946KB(41645)
The linear stability of thermocapillary convection in annular pools is studied through the Chebyshev-collocation method. As Pr=6.8, the ratio of outer radius and inner radius is 0.5, and the range of aspect ratio A is from 0.25 to 1.4, numerical results show that the critical mode of the flow are oscillating. The critical Marangoni number, critical wave number and oscillating frequency decreases as A increases. Energy analysis shows that surface tension in the radial and azimuthal directions plays a leading role in the variation of perturbation energy. And the interaction between perturbation flow and the basic flow is small compared to the two former terms. We find out that the work done by the surface tension in the radial direction reaches minimum were analyzed, while the work done by the surface tension in the azimuthal direction and the interaction between the perturbation flow and the basic flow reach maximum, as A=0.8.
Ground Experiment Study of Evaporation Phase Change for Space Experiment Device of TZ-1 Cargo Spaceship
LIU Wenjun, ZHU Zhiqiang, LIU Qiusheng
2016, 36(4): 481-486. doi: 10.11728/cjss2016.04.481
In order to develop space scientific experimental study of heat transfer law of the evaporation phase change and explore the influence of gravity on the evaporation and heat transfer process on the TZ-1 cargo spaceship, a set of experimental platform of ground evaporation is designed to study the evaporation phase change of FC-72 liquid. By using of infrared thermal imager, heat flux meter and differential thermocouple, the interface changes, evaporation surface characteristics, fluid properties, and Marangoni convection cell changes etc. are observed. of FC-72 liquid layer under different temperature and volume of liquid injection. Then the liquid layer temperature difference, surface temperature field, heat flux value, evaporation rate and convection cell structure of the two phase fluid are obtained. The experiment results show that the evaporation rate is proportional to the temperature difference between the FC-72 layer and the evaporation platform surface. And the evaporation rate is also proportional to the volume of liquid injection. In addition, buoyancy convection cells and Marangoni convection cells emerge in the evaporation process. These results are of important guiding significance for space scientific experiments. The experimental medium and material of space experiment can be decided according to the results of ground evaporation experiments. Consequently, the operating conditions, parameters, and procedure of space experiment can be optimized. Part of the ground experiment results will directly act as the scientific achievements of the ground and space comparison experiments.
Theoretical Analysis for the Elastic Instability of Thermocapillary Liquid Layers for Upper Convected Maxwell (UCM) Fluid
HU Kaixin, HE Meng, CHEN Qisheng
2016, 36(4): 487-491. doi: 10.11728/cjss2016.04.487
The linear stability of thermocapillary liquid layers for Upper Convected Maxwell (UCM) fluid is investigated. Elastic instability is found. The rate of perturbation growth increases with the wave number. For UCM fluid, the critical Marangoni number does not exist, which is different from Newtonian fluid. Instead, a critical wave number is found above which unstable elastic waves appear. The critical wave number decreases with elastic number and Marangoni number. When elastic number approaches zero, the fluid becomes Newtonian fluid with the critical wave number tending to infinity. The wave speed of elastic wave stays constant for different wave numbers and propagating directions. However, the growth rate reaches its maximum in a specific direction. Energy analysis shows the work done by perturbation stress contributes most to the perturbation energy of elastic wave.
Experimental Facility for Ignition and Burning of Solid Materials aboard SJ-10 Satellite
YIN Yongli, WANG Shuangfeng, LIU Renhao, YANG Jingsong, ZHU Feng, TIAN Liu
2016, 36(4): 492-496. doi: 10.11728/cjss2016.04.492
Ignition of solid fuels and subsequent transition to flame spread is of fundamental interest and practical importance for fire safety. Motivated primarily by fire safety of spacecraft, a renewed interest in microgravity flame spread over solid materials has arisen. With few exceptions, however, research on microgravity flame spread has been focused on thermally thin fuels due to the constraint on available test time. Till now still little is known about flame spread over thick fuels in microgravity. A facility is described, which has been designed to examine the ignition and burning behaviors of thick solids onboard SJ-10 satellite of China. The combustion experiments will be conducted with varying low velocity flow and varying ambient oxygen concentration. Other variables to be tested are the effects of fuel type and geometry. The important observations from space experiments include flame behavior and appearance as a function of oxygen concentration and flow velocity, temperature variation in gas and solid phases, and flame spread rate. The research will focus on:(i) finding a limiting oxygen concentration or flow velocity where a flame will propagate in microgravity, and comparing the limits with those on Earth, (ii) evaluating effects of flow velocity, oxygen percentage and material shape on flame spread modes, and (iii) improving the prediction model of solid material combustion.
Effect of Thermocapillary on the Absolute and Convective Stabilities of a Thin Flim Flowing down a Fibre
LIU Rong, LIU Qiusheng
2016, 36(4): 497-500. doi: 10.11728/cjss2016.04.497
The dynamics of a viscous film flowing down a vertical fibre under the action of gravity and the thermocapillary is analyzed theoretically. This exterior coating flow is driven by a Rayleigh-Plateau mechanism modified by the presence of gravity as well as the variation of surface tension induced by temperature gradient along the interface. A temporal-spacial stability analysis is performed to investigate the influence of the thermocapillarity on the convective/absolute instability (CI/AI) of axisymmetric disturbances. The results show that the thermocapillary plays an important role in determining the CI/AI characteristics in different flow regimes.
Fire Initiation Characteristics of Wire Insulation in Representative Weakly Buoyancy Environment
WANG Kai, XIA Wei, WANG Baorui, KONG Wenjun
2016, 36(4): 501-507. doi: 10.11728/cjss2016.04.501
This paper introduce the ground-based low pressure simulation tests of the Wire Insulation characteristic box that will aboard on SJ-10 scientific satellite (SJ-10). An experimental system with reduced pressure is established to simulate the microgravity environment. The effects of insulation type, insulation thickness and amplitude of the overloaded current on fire initiation characteristics of wire insulation have been investigated at the representative 3kPa environmental pressure. The temperature rise trend and the smoke emission characteristics of wire insulation during fire initiation are obtained. Compared with the results obtained at the normal pressure (1atm), the fire initiation features of wire insulation as the satellite fly in orbit, namely it is at 3kPa pressure, is predicted. The results provide important references for the choice of space experimental conditions in SJ-10 satellite.
Analyses on Ground-based Results of Evaporation-convection Box Experiment Prepared for SJ-10 Satellite
XU Guofeng, ZHU Zhiqiang, LIU Qiusheng, CHEN Xue, LIN Hai, XIE Jingchang
2016, 36(4): 508-512. doi: 10.11728/cjss2016.04.508
SJ-10 evaporation-convection experiment is designed to investigate the coupling mechanism and instability of the droplet evaporation and the convection driven by surface tension, during the process of evaporation phase changing when the droplet is deposited on a heated substrate. The heat transfer of evaporation and the evaporation surface non-equilibrium effect are mutually affected by heat conduction, buoyancy convection and the convection driven by surface tension. On the ground, heat conduction and buoyancy convection both play a leading role, but in the space, buoyancy convection will disappear and the thermal capillary convection rules. To make a contrast with space experiment, the scientific matching test under on-orbit working condition was completed with evaporation-convection box and the scientific data, engineering parameters and experiment images were obtained. At the same time, the ground research results were analyzed, and knowledge of the changing pattern of droplet morphology as well as those of temperature, heat flux, evaporation rate and evaporation flux, was acquired. Finally, according to the results of the experiment, the heat and mass transfer regularity of fluid phase-changing interface on which the mass exchange is happening, is analyzed.
Numerical Simulation of Phase Change and Heat Transfer in Cryogenic Tank under the Ground Microgravity Condition
LI Jiachao, LIANG Guozhu
2016, 36(4): 513-519. doi: 10.11728/cjss2016.04.513
In order to predict the state of spacecraft cryogenic propellant heated on-orbit, a 2D axial Volume-of-Fluid (VOF) computational fluid dynamic model including liquid and gas is established, and the model of phase change is based on the theory which put forward by Lee. As simulation experiments used the liquid nitrogen tank, this article used the liquid nitrogen tank as the object of numerical simulation. The results show that, comparing with the ground condition, the rising rate of the ullage pressure and the pressure value are smaller under the microgravity condition, and the lower the level of gravity, the smaller the rising rate of the ullage pressure and the pressure value. The position and shape of the ullage changes dynamically with surface tension which varies with liquid temperature and the temperature differences in liquid nitrogen zone increase with the gravity reducing.
Experiment for Drop-wise Condensation Heat Transfer by Infrared Thermal Imager
WANG Xuwen, YAN Shuo, LIU Qiusheng, ZHU Zhiqiang
2016, 36(4): 520-524. doi: 10.11728/cjss2016.04.520
T-type thermocouples and an IR (Infrared) thermal imager are used to observe the generation, growth, coalescence and roll off from the cooling surface of the droplets. Results have been found that the surface temperature varies sharply during the drop-wise condensation, which is not the same to the literature assumption of keeping constant at saturate temperature. The temperature of droplets surface increases sharply and decreases gradually during condensation, though the condensation surface keeps at constant temperature. Through analysis, studies have been presented that the small diameter droplets are critical to the whole condensation heat transfer. The diameter of the droplet has been obtained during drop-wise condensation. The surface temperature after the droplets coalescence is different from that at the beginning without condensation and it is found that the surface is covered by precursor film after coalescence.
Effect of Gravity during Condensation of R134a in a Rectangular Minichannel
LI Panpan, CHEN Zhenqian
2016, 36(4): 525-530. doi: 10.11728/cjss2016.04.525
In order to study the effect of gravity on the condensation of R134a in a horizontal single square minichannel with 1mm side length, a Volume of Fluid (VOF) method is adopted to simulate the condensation process. The influence of gravity, surface tension and gas-liquid interfacial shear stress are taken into account. The Continuum Surface Force model is chosen for surface tension. Results denote that the lowest velocity and temperature appears at the corner of channel, where condensation occurs first. The distribution shape of the steam in the cross section of the channel is approximately circular and the condensation increases along the flow direction. In square minichannel, the effect of gravity on condensation can be neglected and the condensation is dominated by surface tension and gas-liquid interfacial shear stress at low and high inlet mass velocity respectively. The influence of gravity in condensation film is unobvious when the minichannel is short. In long minichannel, the condensation accumulates in the bottom of channel because of gravity which is not benefit for condensation heat transfer.
Ground-based Experimental Results of TZ-1 Matching Scientific Condensation Experiment
YAN Shuo, WANG Xuwen, LIU Qiusheng, ZHU Zhiqiang
2016, 36(4): 531-535. doi: 10.11728/cjss2016.04.531
TZ-1 ground matching experiment is important to optimize the space science experiment parameters and technical parameters of two-phase test system. The correctional data for space experiment can be provided through scientific matching condensation experiments on the ground by observation of the influence of condensation experiment condition change on the unsteady condensing. The experiment mainly includes:changing condensing units and steam temperature, to obtain the rule of temporal change so as to guide the space experiment data acquisition and liquid pool heating; validating the influence of steam pressure on the liquid film heat transfer coefficient. Through a series of experiments, it can be seen that the condensation temperature, vapor temperature, extraction pressure also have great impact on the heat exchange coefficient, and at the same time, TZ-1 ground matching experiment has high guiding significance to improve the experiment device, optimize the condition and experimental parameters and improve the reliability.
Study on the Flow Condensation of Mixed Gases of FC72 and Nitrogen
LIAO Xubin, WU Wan, ZHANG Xingbin, HE Zhenhui
2016, 36(4): 536-541. doi: 10.11728/cjss2016.04.536
The flow condensation of mixed gases, compared with pure condensable vapors, is far more complicated. Its condensation rate is influenced by the concentration of the non-condensable gas and the condensing temperature. To deal with the FC72 vapor emitted from the evaporation and condensation experiments of the cargo spaceship, a gas-vapor separator and collector is designed, and an experiment system is set up to investigate its performance. The experiment results show that, on condition that the condenser temperature is constant, the condensation rate is increasing as the concentration of FC72 increasing. As the condenser temperature is approximate -10℃, -13℃, and -15℃, and the concentration of FC72 vapor is higher than 70%, 30%, and 20%, the condensation rate can reach 80%, 70%, and 60%, respectively.
Drop Tower Experiment Study of Fluid Transport with Free Surface in Spacecraft
CHEN XiaoLiang, GAO Yuan, LIU Qiusheng
2016, 36(4): 542-546. doi: 10.11728/cjss2016.04.542
With the development of the space industry, space liquid management become one of the important techniques in realizing in-orbit refueling of the spacecrafts, and free surface flow stability is the critical problem in this field. The experiment set-up is designed for microgravity fluid transport study with two channels. In the experiments, symmetrical channel and asymmetrical channel with identical open length for comparison are used, and 10 experiments in the drop tower of Chinese Academy of Sciences are performed. By analyzing the free surface characters, it is found that there exist three typical flow patterns:subcritical, supercritical and critical. Meanwhile, the critical flow rate is obtained. Finally, the free surface flow characteritics of two different channels are compared.
Visualization Study of Condensation on Copper Surface
ZHANG Leigang, CHEN Zhenqian
2016, 36(4): 547-551. doi: 10.11728/cjss2016.04.547
In this paper, the visualization experiment device for vapor condensation is established, and vapor condensation on the copper surface is studied by use of the device. Firstly, vapor condensation on the copper surface is observed by using high-speed camera. The condensations of H2O, R141b and FC-72 are analyzed. The observation results show that a rebound phenomenon emerge after small droplets are merged by the nearby large droplets, thus the small droplets around large droplets are cleaned out. As the condensation has progressed, small droplets are regenerated in the region where they are merged. The rebound phenomenon is equivalent to prolong the dropwise condensation time, and accordingly enhance the effect of condensation heat transfer. Dropwise condensation does not occur as R141b and FC-72 condenses on the smooth surface of copper. After increasing the degree of subcooling, the residual air in the condenser condenses into small droplets on the condensation film, and coexistence phenomenon of droplet and liquid film emerge. In the process of water vapor condensing on the copper surface, heat flux decreases about 20% when dropwise condensation turns into film condensation. Therefore, the copper surface should be modified to reduce its surface energy, so as to enhance the condensation heat transfer.
Effect of gravity on growth of plant cells
CAI Weiming, JIN Jing, CHEN Haiying
2016, 36(4): 552-556. doi: 10.11728/cjss2016.04.552
Abstract(1389) PDF 872KB(814)
In this review, the biological effects of gravity change on plant cells based on the data obtained from both ground-based research and space experiment on board the Chinese spaceship Shenzhou-8 are discussed. These data demonstrate the impact of direction and intensity changes of gravity on cell wall metabolism during plant gravitropism and cells in the state of weightlessness. The maintaining of cell shape requires the balance between cell wall rigid and cell turgor pressure is assumed. When the turgor pressure is greater than the rigid, the balance is broken which may lead to increased cell volume. Therefore the change of gravity may affect the growth of cells through the influence of the balance between cell wall rigidity and cell turgor pressure.
Facility for Higher Plant Culture on Orbit
TONG Guanghui, YUAN Yongchun, ZHENG Weibo, ZHANG Tao
2016, 36(4): 557-561. doi: 10.11728/cjss2016.04.557
The facility for higher plant culture on orbit is used to investigate the growth phenomenon of higher plant in microgravity environment. It is carried on Chinese Tiangong-2 spacelab, and its objective is to establish controlled ecological life support system on space station or space base. The facility selects arabidopsis (long-day plant) and rice (short-day plant) as experimental samples. It is composed of the module of higher plant cultivation, the module of life guarantee, the module of real-time online detection, and the retrieved unit. The facility has functions such as higher plant cultivation for long period, starting biological experiment on orbit, real-time online observation and fluorescence detection, cyclic utilization of water, nutrition supply, the control and detection of simulating long-day and short-day periodic of sunlight, the control and measure of ambient temperature, adjusting of CO2 concentration, removal of harmful gas, and specimen retrieved by astronaut etc.
Method and Technology of Monitoring the Expression of Flowering Gene Marked with Green Fluorescent Protein in Space Culture Chamber
WANG Lihua, XIE Junyan, ZHANG Yue, ZHENG Huiqiong
2016, 36(4): 562-565. doi: 10.11728/cjss2016.04.562
Green fluorescent Protein (GFP) has been widely used as a powerful bio-luminescence reporter molecule for monitoring gene expression on ground. However, it is still difficult to use GFP as a tool in the space culture chamber for life studies. In this study, we present a technical method, which use the LED as excitation light source, for monitoring and analysis of GFP gene expression of the flowering locus T gene in Arabidopsis thaliana that is controlled by the promoter. The method in this study provides a new technical reference for the gene expression studies in space.
Design of Plant Incubator under Microgravity Environment
XU Zengchuang, ZHANG Tao, ZHENG Weibo, XU Dazhao, GUO Yisong, YUAN Yongchun
2016, 36(4): 566-570. doi: 10.11728/cjss2016.04.566
For the research of the plant's biological effect under microgravity condition and the requirement of microgravity signal transduction, the seeding of Arabidopsis thaliana were cultured under microgravity condition. The plant incubator is mainly composed of cultivate unit, light unit, fixed unit and observational unit. The cultivate unit contains Unit1 and Unit2; the fixed unit contains infusion pump, check value and fluid reservoir; and the observation unit is mainly composed of a visible light camera and multispectral camera. Digital images of plant samples were collected, stored and transmitted in real time during the process of space experiments, and the biological samples were fixed and stored during the culture process. The biological effects of plants under microgravity condition will be studied after the retrieved capsule returning to the ground.
Application of Additive Manufacturing Technology for Space
WANG Gong, LIU Yifei, CHENG Tianjin, LIU Ming
2016, 36(4): 571-576. doi: 10.11728/cjss2016.04.571
Abstract(1101) PDF 1815KB(1306)
Chinese Space Station has planned a large number of scientific experiments and applied research. On-orbit support is critical for the accomplishing of manned space mission during the full life cycle of space station. Nevertheless, resources supplied by cargo aircrafts are difficult to be sustainable. The space additive manufacturing technology is a revolutionary and strategic technique for future space exploration, which has the potential to realize manufacturing on the station demand, and will facilitate deeper space exploration by saving logistics from Earth. 3D printing is an important modeling technique to support space manufacturing with its efficiency and flexibility. The latest research of the on-orbit additive manufacturing is summarized, and its on-orbit application pattern is analyzed by taking account of the requirements of Chinese space station and its manned space missions. Moreover, the challenges and solutions of applying additive manufacturing on-orbit are analyzed.
Universal Testing System for Space Science Experimental Facilities
YU Qiang, WANG Xiaoqing, GENG Baoming, ZHOU Hailian, XU Ziheng, GOU Wenbo
2016, 36(4): 577-583. doi: 10.11728/cjss2016.04.577
To analyze the universal testing system plays an important role in the process of space experiment facilities being developed. A design method of universal testing system for a variety of microgravity science experiment facilities is proposed. By analysis of the characteristics of the payloads, the objects of control are classified, and different operations are used for different control object. The process of the experiments is decomposed as a series of operations on specific time. By configuring the static configuration form, action configuration form and dynamic configuration form, the control of the process of experiments is achieved. The testing system is composed of a computer, a power supply and an RS422 communication interface. For different payloads, the power cable and communication interfaces are uniform, to ensure the testing system is universal. The universal testing equipment serves the development of the experimental facilities. These experiments include:space experiment of evaporation and fluid interfacial effects; study on ignition, soot emission and smoke distribution of wire insulations by overload; investigation of the coal combustion and pollutant formation characteristics under microgravity; study on the colloidal assembling; solidification and crystal growth in space; roles of space radiation on genomic DNA and its genetic effects; potential and molecular mechanism of osteogenic differentiation from human bone mesenchymal stem cells. The universal testing equipment plays a very important role in determining the experimental parameters, the space experimental process, the facility specifications testing, the environmental test, the EMC test, and the facility acceptance check process, etc.
Requirement Analysis for Experiment Facilities of Microgravity Fluid Science on Chinese Space Station
JIA Yanmei, ZHONG Hongen, ZHANG Bochang
2016, 36(4): 584-589. doi: 10.11728/cjss2016.04.584
In this paper, the microgravity fluid experiments on International Space Station (ISS) and Chinese scientific experimental satellite/manned spacecraft are discussed and analyzed. The ISS microgravity fluid science experiment facilities are mainly analyzed, including the fluid physics experiment facility, the fluids integrated rack, the boiling experiment facility and the fluid science laboratory. By considering the space microgravity fluid physics science development demand in China, and drawing lessons from the ISS microgravity fluid science experiment demand for equipment, the future microgravity fluid experiment projects to be carried out on China's space station are put forward. Requirements for the experiment equipment to be addressed and problems to be considered are given. Proposals for design are put forward.
Double-channel Experimental Device Used under Microgravity for in-orbit Fluid Transport in Space
GAO Yuan, CHEN Xiaoliang, LIU Qiusheng
2016, 36(4): 590-594. doi: 10.11728/cjss2016.04.590
Double-channel experimental device used under microgravity for in-orbit fluid transport in space is designed. The device is used to observe the flow in open capillary channel under microgravity, and then the steady characteristic of flow transport is studied. The device with double-channel can observe the flow that has two kinds of sections and flow rate in single experiment. The double-channel device can improve the experimental efficiency and reduce uncertainty in contrast experiment. The key technology and difficulties of the design, such as sealing property and pressure compensation, are also discussed. The device system and experimental step are also presented. In microgravity conditions provided by drop tower, by using HFE7500 as fluid medium, the unsteady flow and steady flow are observed by the double-channel device.