Hardware for biological microgravity experiments in Soyuz missions

CCM produces hardware for biological microgravity experiments since 1982. For three Soyuz missions, CCM provided the experiment hardware in different configurations: TMA-1 “ODISSEA”: Battery powered, autonomous system with experiment units for three biological experiments, each in their own experiment container. TMA-4 “DELTA”: Experiment units and control electronics for four biological experiments in KUBIK. Different hardware configurations and control systems, adapted to the specific requirements for each experiment. TMA-8 mission: Reflight of the TUBUL experiment of the DELTA mission The CCM plungerbox unit is a modular experiment equipment, that can be adapted to the specific requirements of the scientists. Also the mission requirements, such as size and weight limitations, available power and the number of levels of containment are different for each flight. It is the challenge for CCM to provide the optimal hardware configuration, for each space mission, aiming at a maximum scientific result.     

Experiments and simulations of liquid imbibition in aqueous foams under microgravity

We describe the capillary motion of liquid into aqueous foams under microgravity. Experiments in which a constant input of liquid is added to a foam under a variety of controlled experimental conditions (bubble size, cell geometry, bubble interfacial properties) have been performed in parabolic flights and in the MAXUS 6 sounding rocket. For comparison, we also performed numerical simulations, based on the foam drainage equations in which the gravitational contributions are removed. The agreement between these simulations and the experimental data is good, and the quantitative adjustment between them enables us to estimate foam permeabilities and surface shear viscosities.     

Analysis on hopping mechanism of planetary robotic vehicle by microgravity experiments

For future exploration missions to small planetary bodies, in-situ surface observation by robots would be a promising method to investigate the target body whose surface gravity is very small. The authors have researched the mobility system under the microgravity environment and proposed a new mobile system which drives a robot by hopping. Due to the uncertainty of the escape velocity from the target small body, the hop velocity of the robot has to be controlled on-board. This paper proposes a velocity control method of the hopping mechanism, which was evaluated by microgravity experiments and compared with numerical simulation analyses.     

Synthesis of composite emulsions and complex foams with the use of microfluidic flow-focusing devices

A method is described for the formation of stable, composite aqueous emulsions of 1) combinations of distinct families of bubbles of nitrogen, 2) combinations of distinct families of droplets of an organic fluid (either perfluoro(methyl)decalin or hexadecane), and 3) combinations of bubbles and droplets. A system of two or three microfluidic flow-focusing units is coupled to a single outlet channel. The composite emulsions can be precisely tuned, both in their composition and in the number fraction of components--either bubbles or droplets--of different types. The use of microfluidic technology, with closely coupled flow-focusing units, guarantees that the emulsions are mixed locally at a controlled local stoichiometry. The emulsions self-assemble in a nonequilibrium process to form a wide variety of highly organized periodic lattices.     

Systematic investigation of the sorption properties of polyurethane foams for organic vapors

Polyurethane foams (PUFs) have long been used for the sampling of airborne organic pollutants. However, a comprehensive investigation of their sorption properties for various organic compounds is still lacking. Here we present a systematic sorption study for a diverse set of up to 100 compounds at temperatures between 15 and 95 degrees C, at various humidities, and for various types of PUFs. The results can be summarized as follows: The performance of PU-ethers is not susceptible to the humidity of the sampled air. Variability between different types of PU-ethers is small, and the compound variability in the sorption constants as well as the enthalpies of sorption can accurately be described with linear free energy relationships (LFERs) presented in the text. PU-esters revealed an inferior sorbent behavior as compared to PU-ethers: sorption was kinetically hindered and was affected by humidity. Sorption varied between different types of esters and prediction with LFERs was less accurate than for the ethers.     

Impact deformation of rigid polymeric foams: experiments and FEA modelling

The ABAQUS Finite Element package was used to model the impact response of low-density polystyrene foam. Uniaxial compression impact data was used for the material model, rather than the required hydrostatic compression data. The response of the *FOAM material model differed significantly from the polystyrene foam response, especially in simple shear and tension. Predictions were made of the impact response of a pyramidal foam block, and rectangular blocks indented by various shapes, under plane strain conditions. The predicted deformation fields were the same as those in high-speed videos, when crack growth was absent. The predicted indentation forces close to experimental values, except for the small diameter indenter. Major crack growth, in some indentation impacts, caused the force to be significantly lower than that predicted.     

ISS experiments for the clarification of boiling and two-phase flow in microgravity and for the development of high-performance space cold plates

Inflow boiling, gravity effects on the distribution of both phases are observed in a heated tube and heat transfer coefficients due to two-phase forced convection is deteriorated in microgravity. In narrow channels between heated and unheated plates, the increase in subcooling enlarges a size of flattened bubble and reduces the frequency of detachment under microgravity conditions resulting the emphasis of heat transfer deterioration. To clarify reasons for the unknown behaviors of interfacial distribution and corresponding characteristics in heat transfer not easily be clarified through the experiments on ground, the opportunity on the experiments utilizing long-term microgravity duration realized in ISS is required. The experiments on microgravity boiling and two-phase flow are proposed by the collaboration of researchers in five countries. A common test loop is designed to conduct multiple experiments by the interchangeable structures of test sections; a transparent heated tube for the visualized flow boiling, a stainless tube for the measurement of CHF data, a copper surface for the heat transfer data of nucleate boiling with superimposed liquid flows in a duct, a glass heated plate with multiple array of small temperature sensors and transparent heaters for the clarification of mechanisms in nucleate boiling heat transfer, and one or two models of cold plates for practical applications. A direction of researches in the present discipline is proposed based on the existing experimental results and on the idea developed by the present authors.     

Fabrication and experimental investigation of metal grid structure-reinforced aluminum foams

This paper put forward an innovative approach for fabricating reinforced aluminum foams through melt foaming method, where the metal grid structure (MGS) was used as a structural skeleton. Samples with a density ranging from 0.31 to 0.56?g/cm³ were fabricated and presented uniform bubbles. The major surface of MGS was covered with a layer of alloy matrix. Compression tests revealed that the compressive plateau phase was transformed into three small phases, where two slight peaks as well as three valleys were detected. In addition, the maximum compressive stress and energy absorption capacity were improved dramatically especially in low-density samples.     

Dynamic investigation of hard viscoelastic materials by ball bouncing experiments

An experimental device is described for studying the behaviour of a material subjected to the impact of a rigid spherical indentor, in the temperature range ?25 to +90° C. For each experimental run performed on a quasi-semi-infinitely hard viscoelastic PVC material, the coefficient of restitution, the duration of impact and maximum penetration were measured. From a series of runs performed with different impact velocities, the effective damping was computed as well as the dynamic hardness. Comparison with a periodic test method proved to be fairly good. In particular the same results on specific losses were obtained by both methods, as long as the impact kinetic energy did not exceed 170 mJ. Furthermore an estimate of the storageE modulus can be made from the contact time. As this paper deals with linear viscoelasticity, the specific deformation energies involved are not too high.     

The development and investigation of superconducting magnetic systems for physical experiments

Superconducting solenoids designed for different physical experiments are described. The solenoids are made of multifilament niobium titanium wires and are connected in series. The magnetic induction achieved at 4.2 K is 9.5 T and with the use of an iron yoke with magnetic flux concentrators an additional 1.5–2 T could be added to the operating volume of about 50 cm³. Various modified cryostats which allow operation for several days without liquid helium refilling and which permit a wide range of physical experiments are described.     

An investigation on the dynamic response of polymeric,metallic, and biomaterial foams

Mechanical characterization of foams at varying strain rates is indispensable for the selection of foam as core material for the proficient sandwich structure design at dynamic loading application. Both servo-hydraulically controlled Material Testing System (MTS) and Instron machines are generally considered for quasi-static testing at strain rates on the order of 10⁻³ s⁻¹. Split Hopkinson pressure bar (SHPB) with steel bars is typically utilized for characterizing metallic foams at high strain rates, however modified SHPB with polycarbonate or soft martial bars are used for characterizing polymeric and biomaterial foams at high strain rates on the order of 10³ s⁻¹ for impedance match between the foam specimens and bars. This paper reviews the effect of strain rate of loading, density, environmental temperature, and microstructure on compressive strength and energy absorption capacity of various closed-cell polymeric, metallic, and biomaterial foams. Compressive strength and energy absorption capacity increase with the increase in both strain rate of loading and density of foams, but decrease with the increase in surrounding temperature. Foams of same density can have different strength and can absorb unequal amount of energy at the same strain rate of loading due to the variation of microstructure.     

微重力环境低温流体无排气加注过程数值研究

针对加注系统受注贮箱,采用CFD方法就液氮贮箱无排气加注过程开展数值仿真,对比了不同重力水平下的无排气加注性能,分析了加注口结构、壁面初始温度、加注流体温度和加注流量等因素对微重力无排气加注性能的影响规律。所构建的二维轴对称模型将流体区与固壁区一起作为求解区域并划分网格,并通过植入用户自定义程序(UDF)计算加注口液体闪蒸过程及气液之间的热质交换。经过实验数据验证,该模型能够合理展示箱内温度场分布和相分布情况,并获得贮箱压力等参数变化信息。数值计算结果表明:(1)加注条件相同时,微重力工况较常重力工况体现出更好的无排气加注性能。(2)微重力条件下,无排气加注性能几乎不受加注口结构的影响,壁面初始温度和加注流体温度越高,贮箱压力越高,加注流量仅对加注时间有显著影响。     

Numerical investigation of the effect of surfactants on the stability and rheology of emulsions and foam

The simple shear flow of ordered and random, non-dilute and concentrated emulsions resembling foam is considered in the presence of an insoluble surfactant. Numerical investigations conducted by the method of interfacial dynamics for Stokes flow combined with an implicit finite-volume method for computing the evolution of the surfactant concentration illustrate the effect of the surfactant on the rheological properties of the emulsion and on the dynamics and stability of the evolving microstructure. Studies of ordered two-dimensional systems, where the suspended phase is distributed on an evolving doubly-periodic lattice, show that, depending on the capillary number, a surfactant may either destabilize or stabilize a concentrated emulsion by promoting or preventing the rupture of thin films developing between the interfaces of adjacent drops. The capillary number, viscosity ratio, and surfactant diffusivity are found to play an important role in determining the rheological properties of the emulsion and the geometrical properties of the evolving microstructure. Large-scale numerical simulations of random two-dimensional systems with 25 drops suspended in a doubly-periodic flow suggest that the qualitative effect of a surfactant is not altered by strong hydrodynamic interactions associated with intercepting or clustering drops.     

Primary investigation on sound absorption performance of highly porous titanium foams

A novel sort of cellular titanium foam, whose total porosity was achieved as high as 86%–90% and main pores were spherically millimeter-scaled, was recently prepared successfully by an improved foaming method of melting the metallic powder. This titanium foam showed a good performance of sound absorption, and its sound absorption coefficient could be more than 0.6 in the sound-wave frequency range of 3150–6300 Hz and even exceed 0.9 at the resonance frequency. The main mechanism of sound absorption for this foam should be of interference silencing due to the surface reflection when the sound wave frequency is lower than about 4250 Hz, and the viscous dissipation when the frequency is higher than about 4250 Hz. A reticular product with millimeter-scaled pore size and about 90% porosity was also made by means of slurry-immersed sintering, and the resultant titanium foam might display an effect for sound absorption, but on the whole, its absorption was evidently inferior to that of the cellular product. The corresponding sound absorption coefficient could not be above 0.2 until sound-wave frequency is higher than 3150 Hz, keeping a relatively low value except for resonance occasion only, on which it could reach up to around 0.9 at about 4000 Hz.     

Solid fuel combustion experiments in microgravity using a continuous fuel dispenser and related numerical simulations

The conventional way of determining the flammability characteristics of a material involves a number of tedious single-sample tests to distinguish flammable from non-flammable conditions. A novel test device and fuel configuration has been developed that permits multiple successive tests for indefinite lengths of thin solid materials. In this device, a spreading flame can be established and held at a fixed location in front of optimized diagnostics while continuous variations of test parameters are made. This device is especially well-suited to conducting experiments in space (e.g. aboard the International Space Station) where the limited resources of stowage, volume, and crew time pose major constraints. A prototype version of this device was tested successfully in both a normal gravity laboratory and during low-gravity aircraft trials. As part of this ongoing study of material flammability behavior, a numerical model of concurrent-flow flame spread is used to simulate the flame. Two and three-dimensional steady-state forms of the compressible Navier-Stokes equations with chemical reactions and gas and solid radiation are solved. The model is used to assist in the design of the test apparatus and to interpret the results of microgravity experiments. This paper describes details of the fuel testing device and planned experiment diagnostics. A special fuel, developed to optimize use of the special testing device, is described. Some results of the numerical flame spread model are presented to explain the three-dimensional nature of flames spreading in concurrent flow and to show how the model is used as an experiment design tool.     

Convection and heat transfer experiments in supercritical fluid under microgravity: From MIR to ISS

The results of two series of space experiments carried out onboard the MIR in 1999–2000 are presented. The experiments were undertaken to study the effect of microgravity environment as well as specially excited vibration on heat spread from a point source inside a cell filled with SF₆ near its critical point. New space experiments are proposed to continue the series interrupted by the deorbiting of the MIR. These proposals are the central point of the CRIT project planned for the realization onboard the Russian Segment of the ISS.     

Numerical and experimental investigation of solid particle motion in a fluid cell under microgravity

This research aims at understanding the mechanisms and parameters that affect particle motion induced by g-jitter. Simultaneous experimental (parabolic flights) and numerical work was conducted to study the motion of a spherical particle in a microgravity environment subjected to vibrations in either horizontal or vertical direction. The data from both vertically and horizontally vibrated experiments clearly show that the investigated particle properties, size and density, affect the amplitude of the particle motion. In all experiments the amplitude of the particle motion increased with the density and diameter of the particle in the cell frame of reference. It was also observed that the particles moved at the frequency equal to that of applied vibration. These results are consistent with the preliminary numerical simulation predictions. Numerical simulations also showed that increasing the viscosity of the surrounding fluid would reduce the amplitude of the particle motion.     

Improvement of the foaming process for 4045 and 6061 aluminium foams by using the Taguchi methodology

Taguchi methodology has been applied to the production process of aluminium foams to investigate the variability detected in several properties (including bulk density, outward appearance and density homogeneity along foaming direction), for foaming tests carried out under identical conditions. The analysis of the process has been performed separately for two different alloys, the 4045 and 6061. The results have allowed finding the main factors that influence those properties. In addition, it has been possible to establish those foaming conditions able to minimize the variability in density, to improve the outward appearance and to obtain a higher homogeneity in density, all at the same time. Different final factors have been found for the two alloys; such differences have been explained in terms of the different viscosity of the aluminium melts as well as the different content of foaming agent.