P21
ISS 用 CO2 吸脱着装置の CO2 吸着特性に与える水分の影響○吉田拓，鈴木進補（早大），桜井誠人，大西充（JAXA）

Effect of Moisture Concentration on CO2 Adsorption Characteristics of
CO2 Adsorption/Desorption Device for ISS○Taku YOSHIDA, Shinsuke SUZUKI (Waseda Univ.), Masato SAKURAI, Mitsuru OHNISHI (JAXA)For long stays on board the ISS, it is necessary toreuse/recycle essential materials. Our research group developeda smaller/simpler CO2 adsorption/desorption device in which
zeolite 5A is an adsorbent. The relationship between moistureconcentration and KFav was evaluated quantitatively. KFav is anindicator of the effect of moisture on the amount of adsorbable
CO2. We will discuss the acceptable moisture concentrationfrom these results.

is therefore concluded that moisture concentrations in the rangeof 0.5~1.2 g/m3 have no significant impact on adsorption
capacity. The performance of the device will remain stable.

1.0

C/C0

1. Introduction

0.5

experimentfitting

2. Experimental Proceduret0

0.0

Experimental apparatus and procedures were based on
previous research1). An adsorption bed with height Z of 0.443 m
was used. CO2 breakthrough experiments were performed withchanging moisture concentrations generated by a simple dryer.
Concentrations were ranging from 0.5 to 1.2 g/m3, which covers
values typically found at the ISS (0.73~1.16 g/m3)2) 3). The inlet
gas velocity u was set at 9.86 m/min. The breakthrough curve
was obtained by measuring the time dependence of the ratio of
the CO2 concentrations C (exit) to C0 (entrance). Experiments
were halted as soon as the ratio reached 0.99. The desorption
phase was taken for 200 min.

0

100
200
Time θ (min)300

Fig.1 Breakthrough curve and fitting curve(moisture concentration A=1.10g/m3)
4

KFav (1/min)

3
2
1

3. Results and discussions
Fig.1 shows an example of a measured breakthrough curveand fitting curve obtained using a least-square method on
experimental data. Data was fitted to equation (1)4).

0
0.4

0.6
0.8
1.0
Moisture concentration A (g/m3)

1.2

Fig.2 Relationship between KFav and moisture concentration(1)

4. Conclusion
Fig.1 shows that difference between experimental data andfitting is small around θ = t0, and large around C/C0 = 0~0.2, and0.8~1.0. Also, KFav is lower at θ < t0, than at θ > t0. It isconceivable that this phenomenon was caused by temperaturedeviations during the preparatory desorption phase1).
Fig.2 shows that KFav did not significantly vary withchanging moisture concentration. This result shows that theshapes of the breakthrough curves are similar regardless of the
moisture concentration in this range.
The total amount of adsorbed CO2 can be calculated
according to equation (1). As KFav values differ only
insignificantly at the specified moisture concentrations, thesevalues are the adsorption capacity of the bed. From the results it

・・・

The parameter KFav does not change significantly withchanging moisture concentration.
The fitting results of equation (1) to experimental data
show that KFav is lower at C/C0 < 0.5, than at C/C0 > 0.5.
This might be caused by temperature deviations during the
preparatory desorption phase.
In the moisture concentration range of 0.5~1.2 g/m3, ourdata indicate that the amount of CO2 adsorption in practicaldevices will not change significantly.

References
1)
2)
3)
4)

－94－

A. Yokohama, S. Suzuki, M. Sakurai, A. Shima, Int. J.
Microgravity Sci. Appl., 30, 2, 2013, 94.
P. O. Wieland, NASA Technical Report, 1998-206956, 1998, 59.
I. Terada, J. Iwamoto, H. Miyake, Membrane, 21, 5, 1996, 306.
K. Kawazoe, Y. Takeuchi, J. Chem. Eng. Japan, 7, 1974, 431.

P22
放射光を用いた液体 Si の動的構造因子の測定○高橋真人，北村洸太，岡田純平（JAXA），水野章敏（学習院大学），正木匡彦（芝浦工業大学）

Measurement of Dynamical Structure Factor of Liquid Si by Using Synchrotron Radiation○Makoto TAKAHASHI, Kouta KITAMURA, Junpei OKADA (JAXA), Akitoshi MIZUNO (Gakushuin Univ.),
Tadahiko MASAKI (Shibaura Institute Tech.)

1. Introduction
Recently, the thermo-physical properties of moltenmaterials can be studied experimentally by using thelevitation techniques. Especially, the relaxation phenomena,such as viscosity, can be observed with high precision by
oscillation droplet method. In addition to that, the levitation
techniques make available to study the undercooled liquidstate or unstable state of matters. In near future, drop
levitation method allows us the observation of material
properties with much more high with the application of
microgravity environment in space where is the lessdisturbances caused by gravity on ground.
Form the microscopic points of views, the relaxation
phenomena are closely related to the atomic dynamics inliquids. It is well known that the static structure of
non-crystalline materials such as liquid metals can beanalyzed by X-ray diffraction. Recently, joint using thesuper photon ring-8GeV(SPring-8), provides us the chanceof the observation of the atomic dynamics of matters withthe use of the inelastic x-ray scattering (IXS). Then, we canobserve the atomic dynamics in undercooled liquids by the
combination of IXS and levitation methods.
As the first step for the understanding of atomic
dynamics in the undercooled liquid metals, we observed theatomic dynamics of liquid Si by the combination ofelectrostatic levitation method and the high resolution
inelastic X-ray scattering facility in SPring-8.

application of high voltage (~20kV) to electrodes. The
sample was heated to by two laser diodes. The levitation ofsamples can be kept for around an hour. Dynamical
structure factor S(Q, ) was measured during the levitationof sample. The sample temperature was measured by apyrometer.

Fig.1 Electrostatic levitation furnace
3. Results and Discussion
The graph in Fig. 2 shows the dynamical structure factor
S(Q, ) of liquid Si at a temperature close to the melting
points, in which momentum transfer, Q, was 4.92nm-1,and
ranges of energy transfer, , was -30meV~30meV. The
elastic peak was observed at the center of spectrum and theinelastic peak was observed at 0±10meV. The atomic
dynamics of liquid Si will be discussed in the poster
session.

2. Experimental Method
The spherical sample of Si whose diameter was 2mm
was made in glovebox filled with Ar gas. The synchrotron
radiation experiment was carried out by the high resolution
inelastic X-ray scattering facility at the BL35XU in the
Spring-8. The energy of incident X-ray was 21.75keV, andthe energy resolution was 1.6meV. Levitation of sample
was carried out by an electrostatic levitation furnace which
was developed to be able to install in the beamline. The
chamber was evacuated to 10-5Pa with a vacuum pumps. As
shown in Fig.1, the charged sample between two electrodes
was levitated by the electrostatic force due to the－95－

Fig.2 Dynamical structure factor of liquid Si

P23
機能性界面制御剤で調製した W/O エマルションの安定性に対する重力場の影響○山﨑貴広（千葉科学大），飯島聡，遠藤健司，酒井健一，酒井秀樹，阿部正彦（東京理科大），
夏井坂誠（宇宙航空研究開発機構），山下裕司，坂本一民（千葉科学大・東京理科大）

Effect of Gravity on the Stability of W/O Emulsion Prepared by AIM○T. YAMAZAKI (Chiba Inst. of Sci.), S. IIJIMA, T. ENDO, K. SAKAI, H. SAKAI, M. ABE (Tokyo Univ. ofSci.), M. NATSUISAKA (JAXA), Y. YAMASHITA, K. SAKAMOTO (Chiba Inst. of Sci./Tokyo Univ. of Sci.)
1.

Introduction

Emulsion disruption can occur through four processes;
creaming, flocculation, coalescence, and Ostwald ripening(Fig.1). Every emulsion goes toward phase separation atequilibrium via one of or multiple routes shown in Fig.1 toachieve minimum interfacial area between water and oil. In spiteof wide range of industrial applications, the theoreticalunderstanding on the long-term stability of emulsion has notbeen well established. Active interfacial modifier (AIM) has
unique properties at the water/oil interface due to its extremely
lower solubility either in water or in most of organic solvents, incontrast to the common surfactants. Our previous studies
revealed that a hybrid amphiphilic polymer (AIM-FN)
consisting of a silicone backbone modified with hydrocarbon
chains and hydrolyzed silk peptide creates long term stablewater-in-oil (W/O) emulsion in the wide composition range of
AIM-FN/water/silicone oil (D5) system. For the W/O emulsion
using AIM-FN, coalescence hardly takes place even hypercentrifugal force is applied, although creaming and flocculation
are observed. Therefore, the objective of our present study is toinvestigate the emulsion stability in the AIM-FN/water/D5
system under quasi-microgravity set by 3D clinostat.

Fig.2 3D Clinostat
The stability of emulsion was evaluated under hypercentrifugal force and quasi-microgravity in the clinostat. The
emulsion droplet size and phase separation degree were
measured as the stability factors by visual and microscopic
observations, respectively.
2.2 Materials and Emulsion Preparation
Hydrolyzed silk PG-propyl methylsilanediol crosspolymer(AIM-FN) was used as AIM. A commercial silicone emulsifier(KF-6038; lauryl PEG-9 polydimethylsiloxyethyl dimethicone,
Shin-Etsu Chem. Co., Ltd) was used as a reference. Decamethyl
cyclopentasiloxane (D5, Dow Corning Toray Co., Ltd) was usedas oil and ultrapure water (>18MΩcm) was used.
AIM-FN or KF-6038 was dispersed in D5 at 70 ℃, thenwater was added under voltexmixer agitation or by thin-film
spin mixer (Filmix®, PRIMIX Co.) to obtain an emulsion.

3. Results and Discussions
The emulsion creaming stability is accelerated by hypercentrifugal force according to the Stokes law expressed as afunction of the density difference of water-oil () and theviscosity of the continuous phase (), and the size of thedispersed phase (d). The phase separation (W/O+O) was
observed under hyper-centrifugal force regardless of  and 

Fig.1 Emulsion disruption processes; creaming,
flocculation, coalescence, and Ostwald ripening. (WithAIM under microgravity, destabilization factor becomes
only Ostwald ripping)

2. Experiment
2.1 Equipment and Stability Evaluation
A 3D clinostat (Mitsubishi Heavy Industries) was used tocreate time-averaged microgravity. The rotational twin bodies
equipped in the 3D clinostat individually turn around in all
directions, providing quasi-microgravity environment artificiallyon ground. The recent study reported that the device can attain amicrogravity environment of 1×10-3G [1].

modulated for different oils. Although creaming followed Stokes
law, there are no coalescence observed for three oils and sizes
and distributions of particle are kept un-effected by hypercentrifugal force. Hence, for the emulsion with AIM
destabilization factor becomes only Ostwald ripping under
microgravity. In our presentation, we will show further resultson the emulsion stability under quasi-microgravity in the 3D
clinostat and discuss the gravitational effect on the deterioration
kinetics of emulsion.
[1] N. Komatsu et. al, Mitsubishi Heavy Ind. Tech. Review, Vol..35,
No.5 (1998)

－96－

P24
微小重力環境下における液柱マランゴニ対流の不安定性に与える
表面からの熱授受の影響○田崎倫之（筑波大院），松本聡（JAXA），鴨谷康弘（ケースウェスタン大），西野耕一（横浜国立大）上野一郎（東京理科大），小宮敦樹（東北大），今石宣之（九州大），矢野大志（横浜国立大院）
金川哲也（筑波大），金子暁子（筑波大），阿部豊（筑波大）

Influence of Heat Transfer at Free Surface on Instability of Marangoni Convection in Liquid
Bridge under Microgravity Condition○Michiyuki Tasaki (University of Tsukuba), Satoshi Matsumoto (JAXA),
Yasuhiro Kamotani (Case Western Researve University), Koichi Nishino (Yokohama National University),
Ichiro Ueno (Tokyo University of Science), Atsuki Komiya (Tohoku University),
Nobuyuki Imaishi (Kyushu University), Taishi Yano (Yokohama National University),
Tetsuya Kanagawa (University of Tsukuba), Akiko Kaneko (University of Tsukuba),
Yutaka Abe (University of Tsukuba)
1.

Introduction

As is well known, the Marangoni convection, it is classified
as natural convection same buoyancy convection due to density
difference. There is a driving force only on the surface toMarangoni convection. Surface tension is the power to reduce
the surface area. In general, surface tension, when thetemperature difference exists along the surface becomes stronger
with decreasing temperature, and the convection is generated
surface is pulled in the low temperature region. Flow is steadywhen the temperature difference is small, but the flow istransition to the oscillatory flow to be above a certain
temperature difference1). Although this transition point isintensively affected by the heat transfer2), the reason is unclear.
The purpose of this study is elucidation of the influence of heattransfer on the oscillating flow generation mechanism.

2.

heat loss from the surface of the liquid bridge. We discussed theinfluence of heat loss from the results of this experiment.

Fig. 1

Experimental apparatus

Experiment

Figure 1 depicts the schematic diagram of the experimental
apparatus. We visualized from the side and upward. The
constant temperature cold disk to see the effect of heat loss hason the oscillatory flow transition and allowed to transition theflow raises the temperature of the heating disk in this study.
Transition point was determined from the temperatureoscillation by a short period of time FFT analysis. Figure 2
shows described the dependency of cold disk temperature on thecritical Marangoni number, Mac. Furthermore, Cold disk has
decreased around 24 degrees, and that the critical Marangoni
number is different to three times. However, the critical
Marangoni number is hardly changed for the case that cold disk
temperature exceeds 24 degrees. The increase of cold disk
temperature represents an increase of heat loss from the liquid
bridge. Thus the critical Marangoni number is influenced by

Fig. 2

Critical Marangoni number

References
1)

Preisser, F., Schwabe, D. & Scharmann, , J. Fluid Mech. 126, 545567, 1983.

2)

Kamotani, Y., Wang, L., Hatta, S., Selver, R., & Yoda, S., J. Jpn.

－97－

Soc.

Microgravity Appl. 18, 283-288, 2005.

P25
自己組織化微細構造形成時の対流の構造に与える影響○井内健豊，平井悠司，下村政嗣（千歳科技大），夏井坂誠（JAXA），今石宣之（九大），
辻井薫（中央大）

Effects of Convections for the Formation of Self-Organized Microstructures○Kento IUCHI, Yuji HIRAI , Masatsugu SHIMOMURA (CIST), Makoto NATSUISAKA (JAXA),
Nobuyuki IMAISHI (Kyushu Univ.), Kaoru TSUJII (Chuo Univ.)

1. Introduction
We have reported microporous polymer films can be preparedby casting a solution of hydrophobic polymer and amphiphilicpolymer on a solid substrate by using condensed water droplet
arrays as templates1). In this preparation method, evaporation
cooling induces the condensation of water droplets, which act as
templates of micropores, on the solution surface. However,some defects of pore arrangement are generated by thermal
convection arising from a temperature difference between thesurface and the bottom of the solution 2). By preventing thethermal convection, better films where the micropores are wellordered like single crystalline can be obtained. Herewith, weinvestigate the origin of thermal convections by the
shadowgraph method.

Fig. 2. Shadowgraphs obtained during solvent evaporation

2. Experiment
A photograph of experimental
setup is shown in Fig. 1. Five mlof a chloroform solvent (control)
and a chloroform polymer
solution containing polystyrene
and amphiphilic copolymer1) were
casted on petri dishes, respectively.
After casting the solutions, humid
airflow was blown to the solution
surfaces through a funnel. By
Fig. 1. A photograph ofilluminating the solution with aexperimental setup
point light source, gradation of
shadow reflecting differences in refractive indexes at local
positions is projected on the screen. The solution weights werealso measured in the same condition to calculate the thicknessesof the solutions.

3. Results and Discussion
Fig. 2 shows a series of the shadowgraphs for the cases withor without polymers. The convectional patterns induced bythermal differences were clearly visualized. The convectional
pattern sizes were almost the same at the same timing, andgradually reduced with time passing. In order to check if theconvection is really caused by the evaporation, it was stopped
by covering with a lid and it was confirmed that convectional
patterns were disappeared.

Fig. 3. A graph of solution thickness

Fig. 3 shows the solution thicknesses calculated from thesolution weights. The decreasing rates were almost the same forthe both cases, but in the case of “with polymer”, the rate wasgetting slower after 600s. This is because the surface of thesolution was covered with the condensed water droplets and thesolvent evaporation became difficult. (In case of only
chloroform solvent, water condensation was not occurred).

4. Summary
We successfully obtained shadowgraphs indicating
convectional flow patterns during a microporous polymer film
formation as shown above. We plan to investigate the effect ofaddition of polymers and/or water droplets on the convectional
patterns as further investigations to find a condition that caneliminate a natural convection and provide better films.

References
1)

H. Yabu, Y. Hirai, M. Shimomura: Langmuir, 22, (2006) 9760

2)

H. Yabu, Y. Hirai, M. Shimomura, M. Natsuisaka, and K. Tsujii:
Jpn. J. Appl. Phys., 49, (2010) 110210

－98－

P26
空気圧パワーアシストを用いた宇宙活動での関節機能向上○谷嶋

信貴，グバレビッチ

アンナ，和田裕之，小田原修（東工大）

Improvement of Joint Function in Space Exploration Activities by Pneumatic Power Assist○Nobutaka TANISHIMA, Anna GUBAREVICH, Hiroyuki WADA, Osamu ODAWARA(Tokyo Institute of Technology)
1. Objectives

2. Actuator design (rubbertuator)

Pressure conditions of spacesuits applied to ISS activities
have been designed to decrease to around 0.3 atm as innerpressure, which should require at least 150 minutes for
denitrogenation to prevent decompression sickness of astronauts.
This means that astronauts cannot start their extra vehicular
activity quickly after attaching spacesuits. If emergent
maintenance is needed, the inner pressure of 0.58 atm would besuitable for prompt activity. Therefore, designs of next
generation spacesuit should be higher than 0.58 atm would
make extra vehicular activity more efficient. However, larger
gap of air pressure between inside and outside of the spacesuit
causes cloth expansion as balloon, resulting in extra torque forjoint bending.
In this study, application of pneumatic power is proposed to
improve flexibility of joint. The ideas shown in this presentation
have been selected by considering space environment, elasticity
and flexibility as human muscle.

The present actuator contracts and expands with compressing
air. Structure and mechanism of the rubbertuator is shown in

Fig.1 shows the torque calculated for the arm joint angle with
0.6atm inner air pressure using following formula (1).
N=Lπr2ΔPsinθ···(1)N: Torque (N·m),
L: Arm length (m),Fig.2. Rubbertuator is made from rubber tube covered with fiber
cord. Metal fittings at each end permits the entry and exit ofcompressed air.
Pneumatic power source is the most typical character of therubbertuator. This enables rubbertuator to contain contractelement, spring element and dumper element as human muscle.

Fig.2. Structure and mechanism of rubbertuator
3. Experimental
Experimental procedures are carried out with the following
steps: to pressurize the air tank (0~5 atm), to open the gate valve
to activate the rubbertuator (5mm, 10mm, 20mm in innerdiameter), to close the gate valve and decompress the air tank.
Pressure gauger: Joint radius (m), θ: Arm joint angle (º)ΔP: Inner pressure (Pa).
Compressor Air tank

From Fig.1, maximum torque of 13.3N･m is required when
the arm joint angle is 90°. Therefore, the present achievement of
torque is focused at least more than

13.3N･m. Judging fromthe design with human muscle-like motions, response speed
should be also less than 0.1 second.

Gate valve

Rubbertuator

Fig.3. Experimental equipmentr

4. Results
Figs.4 and 5 show rubbertuator’s performances. From thepresent results, the rubbertuator has started the elastic
deformation from 1 atm in pressure difference. Its spring
constant increases as the inner pressure increase.

Fig.4. Strain increasing rate

Fig.1. Torque for the arm joint angle(r = 0.075m)
Fig.5. Spring constant

－99－

P27
静電浮遊液滴の回転分裂時における界面変形と内部流動挙動◯綿引壮真（筑波大院），松本聡（JAXA），金川哲也，金子暁子，阿部豊（筑波大学）

Interfacial Deformation and Internal Flow Behaviors during Rotational Breakup of
Electrostatic Levitated Droplet◯Soma WATAHIKI (University of Tsukuba), Satoshi MATSUMOTO (JAXA), Tetsuya KANAGAWA,
Akiko KANEKO, Yutaka ABE (University of Tsukuba)

1. Introduction
By using the electrostatic levitation method, it has become
possible to measure thermophysical property of a high melting
point sample without container1). However, there was no
method to measure viscosity in range from 0.1 to 100 [Pa･s].
Our group has proposed a new method to measure the viscosityof the sample within this range2). Our method utilizes rotational
breakup behavior of the droplet, and the measurement error isabout 30% until now. In this study, internal flow during therotational breakup was investigated, and the effect of nonaxisymmerty and mean curvature of the droplet on themeasurement result was evaluated.

Fig. 1 Schematic diagram of electrostatic levitator

3. Results and discussion

2. Experimental method
The experimental apparatus is illustrated in Fig. 1. Two
cylindrical electrodes were placed vertically opposite.
Conductive glass window was fixed on the bottom of the upper
electrode. The acrylic needle jig was filled inside the bottom
electrode. The injection needle is inserted through the hole in
the acrylic fixing. The droplet was formed at the tip of theneedle. The droplet was charged electrically since the needle
was connected to a power supply. When a negative high voltage
was applied to the upper electrode, the droplet was levitated in
the air by electrostatic force. The vertical position of the droplet
was detected by using the He-Ne laser and the position detector,
and controlled by adjusting the voltage of the upper electrodethrough the PID algorithm. The electrodes were placed in theacrylic chamber. The droplet was rotated by acoustic torquegenerated by a pair of orthogonal positioned loudspeakers
attached on the side wall of the chamber 3). The rotational
breakup behavior of the levitated droplet was observed by using
two high-speed video cameras and two metal halide lamp. The
images were taken from both upper and side of the droplet. To
observe the internal flow, the fluorescent particles were mixed
in the test fluid in advance. The particles on the horizontal planeof the droplet were fluorescent by sheeted laser beam generated
by Nd:YAG laser and cylindrical lens. The experiments were
performed in normal pressure at room temperature. The test
fluid was Glycerol (density 1260 [kg/m3], surface tension 63

3.1 Rotational breakup behavior
Figure 2 shows the observation results of rotational breakupof the levitated droplet. Time of 0 [ms] indicates the moment ofbreakup. The droplet was elongated and the midpoint diameter
became smaller as the output power of the loudspeakers
increased. Finally, the midpoint of the droplet was pinched off.
In the side view images (a) ~ (c), we found that the midpoint of
the droplet was a non-axisymmetric shape slightly. In the image(d), the droplet was an axisymmetric shape. In the image (e), themidpoint of the droplet was significantly distorted upward. In
the image (f), the droplet was broken up and a satellite droplet
was generated.
3.2 Internal flow
The trajectories of the tracer particle in the droplet just before
rotational breakup for 11.33 [ms] were shown in Fig. 2; whiteallows show the direction of each particle. Figure 3 shows timeseries of the velocities of each particle in the axial and radial
directions. Each color corresponds to the color of the particles
in Fig. 2. As a result, flow velocity in the radial direction aroundthe midpoint of the droplet was constant, on the other hand,flow velocity in the axial direction increased with axial distancefrom the midpoint (Fig. 4).
3.3 Viscosity calculation
The stress balance at the midpoint of the droplet during
rotational breakup2) was modified in the viewpoint of mean
curvature. The modified stress balance is expressed by,[mN/m], and viscosity 1.0 [Pa･s]).

,

－100－

(1)

where ηs, Dmid, m, r, ω, σ, and Hmid are the viscosity, midpoint
diameter, mass of the droplet, length between center and centerof gravity in one side of the lob, angular velocity, surface
tension, and mean curvature, respectively. In the each term of
the eq. (1), the left-hand side, the first and second terms of theright-hand side indicate the viscous stress, centrifugal stress,
and surface tension stress, respectively. The corrective
coefficient by mean curvature Hmid4) is given by,
where R(z) is the distance from long axis of the droplet tointerface. The edge pixel of the droplet interface is obtained via
Canny edge detector algorithm. The edge pixel is approximatedby a hyperbolic cosine function to obtain R(z). Furthermore, left
term except viscosity η are moved to right side, eq. (2) tocalculate viscosity is derived.
,

6.45 mm5.63 mmFig. 2 Top and side views of the levitated droplet during
rotational breakup(2)

Figure 5 shows the value of each term of the eq. (1) andcalculated viscosity by eq. (2). The centrifugal stress term
surpasses the viscous and surface tension stress terms justbefore the breakup, and in this regime, the surface tension stressterm is much smaller than others. By correcting the surface
tension term by mean curvature, the value of surface tension
term increased slightly. The effect of mean curvature of thedroplet became smaller as the droplet approached breakup. In
axisymmetric regime, the result of the viscosity calculation wascloser to the appropriate value with actual viscosity.

Fig. 3 The trajectories of the typical tracer particles
Axial direction

4. Conclusion(1) Flow velocity in the radial direction around the midpoint of
the droplet was constant, in the axial direction increased withthe axial distance from the midpoint during rotational breakupof the droplet.
(2) When the droplet was an axisymmetric shape, the result ofviscosity measurement showed appropriate value as actual
viscosity.
(3) The effect of mean curvature of the droplet became smaller
as the droplet approached breakup.

Radial direction

Fig. 4 Time series of the velocity of each particle in axial andradial direction

References
1)

T. Ishikawa, J. T. Okada, P.-F. Paradis, Y. Watanabe: International
Journal of Thermophysics, 31 (2010) 388.

2)

R. Tanaka, S. Matsumoto, A. Kaneko, Y. Abe: Interfacial
Phenomena and Heat Transfer, 1 (2013) 181.

3)

F. Busse, T. G. Wang: The Journal of the Acoustical Society ofAmerica, 69 (1981) 1634.

4)P. Szabo: Rheologica Acta, 36 (1997) 277.

Fig. 5 Time series of each stress acting on the levitated droplet
central part and estimated viscosity

－101－

P28
ISS を利用したソーレ係数測定方法の改善○長田拓真，橋本栄尭，鈴木進補（早大），稲富裕光（JAXA/ISAS）
伊藤裕一（JAXA），島岡太郎（JSF）

Improvement of measuring method for Soret coefficient on the ISS○Takuma OSADA, Yoshitaka HASHIMOTO, Shinsuke SUZUKI (Waseda Univ.)
Yuko INATOMI (JAXA/ISAS), Yuichi ITO (JAXA), Taro SHIMAOKA (JSF)
1. Introduction
Recently, we performed experiments of “Soret-Facet” on theInternational Space Station (ISS) to measure accurate Soretcoefficients ST1). An effective correction method for thermal
expansion of a quartz glass cell has already been established bysubtraction of the moving distance of interference fringes in thewall side from those in solution side2). Therefore, themeasurement results of “Soret-Facet” on the ISS should becorrected by this method. The validity of the correction method
was confirmed with interference fringes with aligned in theparallel direction to a temperature gradient (vertical fringes, //).
However, the quartz glass cell on the ISS “FACET-cell” hasso thin wall for observation to set enough amount of fringes fora high resolution for accurate ST. Therefore, interference fringes
with aligned in vertical direction to a temperature gradient(lateral fringes, ) were used in the “Soret-Facet”. The lateralfringes have advantages that a proper amount of fringes can be
set with a high resolution even in the thin wall. On the other
hand, the lateral fringes require an additional correction forvariation of distance between fringes during change oftemperature and concentration.
We checked the validity of the correction method for thelateral fringes in the ground experiments by comparing with theresult of vertical fringes. And we discussed the difference of ST
values between with and without the correction of thermal
expansion of FACET-cell.

2. Experimental Procedure
2.1 Ground Experiments
We measured ST of salol – 9 mol% tert-butyl alcohol solution
by a two-wavelength Mach-Zehnder interferometer with

Fig.1 Schematic illustration of the two-wavelength MachZehnder interferometer2)
The center of the observation window was set 2 mm upperfrom the bottom side. Setting temperature program is shown in
Fig.2. At first, both top and bottom sides of the cell were heated
up and kept at 50 °C with Peltier devices for over 24 h(homogenization time th). The mirrors were adjusted so that theinterval of dark lines were about 30 pixels (532 nm) and about
48 pixels (780 nm) in the solution side during homogenization
time for both vertical and lateral fringes. The movies of theinterference fringes were recorded for 21 h (Soret effect time
tsoret) just before the temperature of the bottom side was loweredfrom 50 to 40 °C.
Number of crossing dark lines on the observation point wasmeasured to obtain the moving distance of interference frignes.
We subtracted the moving distance of interference fringes in thewall side from those in solution side to correct thermal
expansion of a quartz glass cell2). The variation of distance
between fringes was corrected in the experiment using lateralfringes.

wavelengths of 532 nm and 780 nm. Fig.1 shows a schematic
illustration of the two-wavelength Mach-Zehnder interferometer.
Then, thermal expansion of the quartz glass cell was corrected
to measure accurate ST. In the ground experiment, ST were
measured by using both vertical and lateral fringes.

Fig.2 Setting temperature program of Peltier devices－102－

2.2 ISS Experiment
We measured ST of salol - tert-butyl alcohol solution by
Solution Crystallization Observation Facility (SCOF) equippedwith the two-wavelength Mach-Zehnder interferometer. The
concentration of tert-butyl alcohol was about 3 mol%. Setting
temperature program was equal to Fig.2. Homogenization time
th was 7 h and Soret effect time tsoret was 10 h. The mirrors were
adjusted for lateral fringes during homogenization time. The
center of the observation window was set 1 mm under from thecenter of FACET-cell.
3. Results and Discussion
Fig.3 shows the pictures of lateral and vertical fringes in 1g
and g. The areas surrounded with the red frames are the cell
walls. The measured values of ST obtained in 1g are 4.4 ± 0.46 ×
10-2 K-1 (//) and 3.8 ± 0.44 × 10-2 K-1 (), which agreed eachother. A proper amount of lateral fringes can be set with a highresolution even in the thin wall of FACET-cell under g byusing lateral fringes.
Wavelength

1g

g

532 nm

Fig.4 Number of crossing dark lines against time under gof 532 nm (a) and 780 nm (b)780 nm

//4. Conclusions



We compared the result of lateral fringes with vertical fringes.
The validity of the correction method for the lateral fringes was
confirmed in the ground experiments. The lateral fringes wereused in the “Soret-Facet” and thermal expansion of FACET-cellcan be corrected without reducing resolution. And the maximum
difference of the obtained ST values between with and without
correction was 70 % of the ST value with correction. Therefore,
the correction is necessary for accurate measurements of ST toeliminate the error of thermal expansion under g.

Acknowledgments

The authors are deeply grateful to Japan Manned Space
Systems Corporation (JAMSS) for the operation of the payloadsof the ISS experiments.
Fig.3 Vertical and lateral fringes in 1g and g

References

Fig.4 shows number of crossing dark lines in the solution sideand the wall side against time under g ((a)532 nm, (b)780 nm).
As shown in Fig.4, the fringes in the wall side move by thermal
expansion of FACET-cell. Therefore, it is necessary to subtract
the moving distances of interference fringes in the cell wall sidefrom those in the solution side. The maximum difference of theobtained ST values between with and without correction was
70 % of the ST value with correction. Therefore, the correction isnecessary for accurate measurements of ST to eliminate the error

1)

S. Suzuki, Y. Mori, Y. Hashimoto, Y. Inatomi, T. Masaki, M.
Watanabe, A. Mizuno, I. Ueno, T. Yamane, T. Itami, M. Katsuta: J.
Jpn. Soc. Microgravity Appl., JASMAC27 (2013) B08.

2)

Y. Mori, Y. Hashimoto, S. Suzuki, Y. Inatomi: Transactions of
JSASS, in press.

of thermal expansion under g.

－103－

P29
ソーレ効果に及ぼす各因子の影響~ISS と地上における 2 波長干渉計を用いた測定~○橋本栄尭，長田拓真，鈴木進補（早大），稲富裕光（JAXA/ISAS），勝田真登（JAXA），
島岡太郎(JSF)

Influence of Parameter on the Soret Effect~Measurements using Two-wave Length Interferometer on the ISS and the Ground~
Yoshitaka HASHIMOTO, Takuma OSADA, Shinsuke SUZUKI (Waseda Univ.), Yuko INATOMI (JAXA/ISAS),
Masato KATSUTA (JAXA), Taro SHIMAOKA (JSF)
1. Introduction

under the g conditions, although it increased under 1g.

The Soret effect plays an important role in solidification andcrystal growth processing operations, and so on. This parameter,
which is called the Soret coefficient ST is described by thefollowing equation.
(1)
1
C

Following reasons are considered for the difference between the

ST  

C0 (1 - C0 ) T

results obtained in 1g and g.
The neutral point of flow of tert-butyl alcohol should exist in
the middle between the top and the bottom. However, theneutral point might have shifted to the higher temperature sidein the g experiments after setting a temperature gradient. In

Here, C0 and C/T are the average concentration and the ratio

this case, the flow direction of tert-butyl alcohol agrees eachbetween the concentration and the temperature gradients at thesteady state, respectively. However, accurate measurement of thetemperature and the concentration is difficult, so the amount of
reliable data of ST is too small to discuss the temperaturedependence of ST.

other between 1g and g experiment.

In this study, we investigated ST under the 1g and the gconditions. The convection-free g conditions were realized in

On the other hand, there is a possibility that the flow
direction of tert-butyl alcohol is different between 1g and gexperiments. Since the ST value itself is an intrinsic property ofa solution system, it is independent from the gravity condition.
Therefore, additional mass transport can be considered in 1g
experiment, such as buoyancy flow.

Kibo/ International Space Station (ISS).

2. Experimental procedure
In the 1g and the g experiments, the samples were preparedby adding 6 and 3 mol% tert-butyl alcohol to the molten puresalol and packed in a quartz cell, respectively. Then, weinvestigated ST by using a Mach-Zehnder interferometer with
two lasers of wavelengths of 532 nm and 780 nm2) on the two
experiments. And we investigated ST by using Solution
Crystallization Observation Facility (SCOF)/Kibo under gconditions, also.
Both top and bottom sides of the cell were heated at the same
temperature by Peltier devices. After the temperature of thesample achieved steady state, the bottom side was set 10 K
lower than the upper side which was kept at the constanttemperature. Then the interference fringes shifted because ofrefractive index change. The variations of ∆T and ∆C were
calculated from shift of interference fringes measured from theinitial homogenization states2).

3. Results and discussion
The measured C showed that the concentration decreased in

Fig.1 Schematic illustration of the Mach-Zehnder interferometer

Acknowledgments
The authors are deeply grateful to Japan Manned Space
Systems Corporation (JAMSS) for the operation of the payloadsof the ISS experiments.

References
1) Y. Inatomi, I. Yoshizaki, K. Sakata, T. Shimaoka, T. Sone, T. Tomobe,
S. Adachi, S. Yoda and Y. Yoshimura: Defect and Diffusion Forum,
323-325 (2012), 533-537.
2) Y. Mori, Y. Hashimoto, S. Suzuki, and Y. Inatomi, Transactions of the
JSASS, in press.

the lower temperature side after setting a temperature gradient

－104－

P30
斜面を用いた低重力装置の開発：斜面摩擦力への対策○伴野貴哉，中村祐二（豊橋技科大），関本孝三（関本技術事務所），野田進（豊橋技科大）Development of Low-gravity Generator vis Slope-sliding Method: Strategy to Minimize Wall
Frictional Force○Takaya BANNO, Yuji NAKAMURA(Toyohashi Univ. Tech.), Kozo SEKIMOTO (Sekimoto PE),
Susumu NODA (Toyohashi Univ. Tech.)
1. Introduction

2. Target of Revision

Living in low gravity environment is a keyword for futuremanned mission to outer space environment. Although anumber of series of microgravity research projects have been
made and fundamentals on microgravity effect on various
science fields have been known, we only come to know the
microgravity effect and the partial gravity effect is still open
question. For instance, it is difficult to answer immediately
following questions; what happens if the human being is
exposed on to the partial gravity field in long term; what is thecritical gravity to be eligible for our body to adopt (adjust)naturally? In order to study such issue, development on afacility to generate the low gravity environment on the earth ishighly demanded.
Previously, we have proposed the concept of “low-gravity
generator” by using the sliding over the frictionless (ideal)slope; named SSMe (Slope Sliding Method) (See Fig.1)1).
According to the demonstration, the concept seems to work,
however, there must be special treatment on the sliding surface
to eliminate the frictional loss. Since it is obvious that thesurface treatment can relax the friction but fail to eliminate it,
there must be another way to introduce external force tocompensate it. Here, we study the possibility to eliminate thefrictional force effectively with high-controllability by using
pulley-drag mechanism.
Although demonstration test isunderway and not ready at present, the design concept shall be
introduced.

2.1 Brief Introduction of SSMe
Although the detail description of the concept of SSMe has
been available in elsewhere1), a brief introduction will be madehere for reader’s convenience. SSMe is handy, less-cost, lowgravity generator by using slope-sliding concept. Consider the
candle flame is formed in the box. When the box with candle
is sliding over the frictionless slope (whose angle of ), theflame does not feel any acceleration in the direction of sliding,however, the normal component of gravity (G*cos; G isgravity acceleration, m/s2) on the slope surface is only
acceleration for the flame to be experienced. Thus any partial
gravity environment can be created in the box once we control
the angle of the slope.
Although the concept and structure are simple enough,technical difficulty is how to treat the residual acceleration
along the sliding direction caused by the frictional force
between the box and the slope, as discussed in our previous
work1).
If it is possible to eliminate the acceleration
component along the sliding direction (namely, in the direction
the box is freely drops), only the normal direction of gravity
component against the slope surface is remained.
2.1 Actual Frictional Force to be CompensatedAs shown in Fig.2, ’MGcos (M: mass of the box, kg) is
the force to be compensated.

According to the previous

demonstration1), by using plastic board spread with chalkpowder, estimated coefficient of kinetic friction (’) is 0.176.
Importantly, this force to be compensated is constant value
during the sliding event once the slope angle is fixed.
Namely, some external force to compensate this much shallbe introduced to fulfill the demand.

Fig. 1. Schematic illustration of the concept of slope-sliding method(SSMe)1)

Fig. 2. Actual force balance subjected to the rack the sliding operation1)－105－

2.2 Candidate Concept: Introducing the Constant Drag
Force toward the Sliding Direction

Since the target is “constant” force (or constantacceleration) in the direction of sliding, one simplest
candidate is to add corresponding (constant) drag force.
Simplest way to achieve this purpose, the following concept
might work as shown in Fig.3, namely, the constant force is
induced by the falling counter weight.

As shown in this figure, motor is installed to roll-up the wire,
just likely belt-conveyer system. The motor has sensor tocontrol the torque to maintain the constant drag force. In thisway, the constant drag force is easily obtained to compensate theprescribed frictional force in the system assisted by torquecontrol circuit.
Let us briefly estimate how it works. First consider thefollowing conditions to estimate the necessary torque-controlled
performance under specific design of the system (coefficient of friction) < 0.1m (mass of the sliding rack) > 0.5 kg
R (radius of pulley) > 0.01 m (angle of slope) = /6 (arbitrary determined)

For given slope angle, it is estimated the necessary torque to becontrolled and the brief results are given in Fig.5.

Fig. 3. Schematic illustration the system to introduce the constant dragforce via falling “adjustable” weight

By adjusting the (counter) falling weight, the frictional force
between the slope and the rack shall be compensated.
However another difficulty (ambiguity) should arise by thisconcept, namely, the additional frictional force between thepulleys and the flexible wire must be considered. To avoid thisproblem, introducing the active control on drag force (notpassive control as shown in Fig.3) sounds reasonable.

Fig. 5. Estimation of necessary torque performance to compensate thegiven frictional force

2.3 Active Control of Drag Force by Introducing Torqueadjustable Motor

The schematic illustration of suggested active control
system is depicted in Fig.4.

Commercially available torque controllable motor can fit inthis range (actually wide range of torque motor is available) sothat this design is ensured to work. Currently we are working
on constructing the system and be ready to perform the test withgravity sensor.

Remarks
The possibility to eliminate the frictional force is studied andthe potential system by generating the constant drag force is
proposed. With such devices, introducing the controllable
low-gravity device in high accuracy is expected. We will now
work to construct the demonstration system to show thisconcept works properly.

References
Fig. 4. Schematics of active control system to compensate the frictional
force

1)

－106－

Nakamura, Y. and Sekimoto, K., Transaction of JSASS (special
issue for 29th ISTS), in print.

P31
濡れ性が異なる円管を用いた沸騰熱伝達特性に対する重力影響○大久保 正基，河南 治（兵庫県大），Peter STEPHAN，Martin FREYSTEIN，
Felix CRÖßMANN（ダルムシュタット工大）

Influence of Gravity on Heat Transfer of Flow Boiling in Tubes with Different Wettability○Masaki OKUBO, Osamu KAWANAMI (Univ. Hyogo), Peter STEPHAN, Martin FREYSTEIN,
Felix CRÖßMANN (Tech. Univ. Darmstadt)

1. Introduction
In recent year，exhaust heat, transporting distance of heatand heat generation density of space applications are increasing.
In order to solve those problems, flow boiling is a prospective
candidate for the cooling system. This system is efficientcooling method because latent heat transfer is caused by phasechange under boiling condition. However, heat transfer about
flow boiling on g has many unclear points such as CHF until
now. Because of flow boiling is not affected by body force(gravity) in g, it is expected that boiling bubbles become hardto detach from heating surface and critical heat flux should bedecreased. Besides, influences on heat transfer of flow boilingby wettability of heating surface, Phan et al reported that heattransfer coefficient at hydrophobic heating surface inrectangular channel (5 mm wide, 0.5 mm height, 180 mm
length) increase under the conditions of quality x = 0.0050.0151). Here we report that the flow boiling experimental
results conducted ESA parabolic flight campaign. Aim of thisstudy is clarify influences of gravity and wettability on flow
boiling heat transfer.

2. Experimental Apparatus and Conditions
This boiling flow experiment was conducted under thedifferent gravity levels; g, g and g. The test loop is mainly
consisted of test section, condenser, tank, pump, flow meter andpreheater. The detailed of the test section shown in Fig. 1 isincluded three transparent heated tubes (THT) having different
wettability of heated surface in series. THT is coated by gold
thin film with the thickness of 10-50 nm, it enable to measure

Fig. 1

Test section of parabolic flight experiment

inner wall temperature of the tube, to heat fluid, to observe flow
through the wall. The different wettability on the heated wall
given by building self-assembled monolayers (SAMs) on thegold film. Tube given SAMs having 1-Dodecanethiol end groupas segment1 (wetting angle74º), normal tube as segment2(48º) and tube given SAMs having 11-Mercapto-1undecanol end group as segment3 (43º) are located. Flow
direction in vertical upward, water is used as a working fluid.
Experimental conditions are mass velocity G = 75-400 kg/m2s,
subcooling Tsub = 0.2-11.6 K, loop pressure P = 0.61-1.16 bar,heat flux qin = 0-550 kW/m2.

3. Results and Discussions
Boiling curve under the conditions of G = 165 kg/m2s, qin = 0550 kW/m2 is shown in Fig. 2. Inner wall temperature of the
THT at onset nucleate boiling, TONB, of the segment1 (74º)
is lower than that of segment3 (43º). In the case of segment1(74º), hysteresis of ONB is a little under all of gravity level.
On the other hand, segment3 (43º) has an inference ofgravity compared segment1 (74º). After boiling, influencesof gravity did not clear in both tubes under low quality region.
The wettability of the heated wall has a small impact in thisregion; heat transfer of segment3 (43º) is slightly higher
than that of segment1 (74º).

References
1)

H. T. Phan, N. Caney, P. Marty, S. Colasson, J. Gavillet: J. Heat
Transfer, 134 (2012) 020901-1-6.

Fig. 2－107－

Boiling curves about segment1 and segment3

P32
沸騰・二相流体ループの加熱円管壁面における気液挙動と熱伝達○今井智敬，大久保正基，河南治（兵庫県立大），大田治彦，新本康久（九州大），浅野等（神戸大），
今井良二（室蘭工業大），松本聡，栗本卓，高岡秀充，坂本道人（JAXA）

Gas-liquid Behavior and Heat Transfer at the Heated Tube Wall in the Boilingand Two-phase Flow Loop○Tomotaka IMAI, Masaki OKUBO, Osamu KAWANAMI (Univ. of Hyogo), Haruhiko OHTA, Yasuhisa
SHINMOTO (Kyushu Univ.), Hitoshi ASANO (Kobe Univ.), Ryoji IMAI (Muroran Institute of Technology),
Satoshi MATSUMOTO, Takashi KURIMOTO, Hidemitsu TAKAOKA, Michito SAKAMOTO (JAXA)

References
1)

M. Kureta, K. Mishima, H. Nishihara, JSME Ser. B, 61 (1995),
4109-4116 (in Japanese).

Target area

Brightness analysis
Target area

Fig. 1

152

Inner wall temperature
dT/ds

Fig. 2

－108－

10

151

0

150
60

-10

Gas-liquid interface ratio [%]2. Results and Discussions
A short transparent heated tube that has 5 mm heated length,
4 mm inner diameter and 6 mm outer diameter as shown in Fig.
1 is used. Fig. 1 is also illustrated the image of flow behavior
and its brightness analysis. In this experiment, the focus ofcamera is tightly focused on the inner-wall of the tube. Fig. 2 isshown an example of the experimental results. The Top figure
shows inner-wall temperature of the tube and temporal
differentiation of the temperature. Bottom figure shows the ratioof gas-liquid interfacial area to target area. Here, the gas-liquidinterface is defined the brightness value below a suitable
threshold, 60 which is corresponding green color region in Fig.1.
Though the view of camera is only from one direction, it could
be found that the transitional tendency of dT/ds and was roughly
coincided with the gas-liquid interface ratio. Increasing of theratio of the gas-liquid interface area caused the decreasing of
dT/ds.

An enlarged view of short transparent heated tube
section (left), an example of flow behavior and its
image analysis (right).

dT/ds [℃/s]

Flow boiling is one of an efficient way to remove large
amount of heat. However, there are large amount of research
work of pool boiling and flow boiling heat transfer, its physicalmechanisms are not yet fully understood. For flow boiling in a
tube, Kureta et al. reported some “time-averaged” heat transfer
data and flow behavior by using short metal heated tube undermany experimental conditions1). However, we could hardly findreports that the relation between transitional heat transfer data
and the local gas-liquid behavior on the heated wall of the tube.
In this report, we presents that heat transfer characteristics
and flow behavior on the heated wall of the tube by using theshort transparent heated tube. A short transparent heated tube
which is coated gold thin film on the inner-wall by electrolessplating method, it is allowable to measure the averaged innerwall temperature and to observe flow behavior through the wallat the same time. The tube is installed to understand themechanism of local heat transfer on flow boiling as anevaporation section, and the relation between transitional gasliquid behavior and inner-wall temperature will be considered.

Inner wall temperature [℃]

1. Introduction

50
40
30
20

7.6

7.8

8
Time [s]8.2

8.4

Histories of inner wall temperature, time changing
ratio of temperature (top), the ratio of gas-liquidinterface area to target area (bottom) (G = 47 kg/m2s,
q = 395 kW/m2).

P33
ガスジェット浮遊法とＸ線散乱を用いた液体 Bi-Ga 合金の構造解析○北村光汰，正木匡彦（芝浦工業大学），水野章敏（学習院大学），小原真司（SPring-8）

Structural Analysis of Liquid Bi-Ga Alloy by using X-ray Scattering with Aerodynamic
Levitation System○Kota KITAMURA, Tadahiko MASAKI (Shibaura Institute of Tec), Akitoshi MIZUNO (Gakushuin Univ)
and Shinji KOHARA (Spring-8)

1. Introduction
In the gravitational field on the earth, phase separation
phenomena in fluids are affected by gravity. Particularly, for theobservation of critical phase separation, such as the liquid-liquid
or liquid-vapor phase separation, the disturbance by the gravity
induces serious problem because the large fluctuation ofconcentration or density is disturbed by the convective flow.
Microgravity environment is regarded as an ideal environment
for the research of these kinds. In the previous research, by using
sounding rocket, S520, the electrical resistivity of Bi-Ga alloys
shows abnormal behavior near the critical point of liquid-liquid
phase separation. The behavior might be related to the growth ofcritical fluctuation, however, the microscopic view of thisphenomena is still open question. In addition, it is known that thelarge concentration fluctuation cause the abnormal behavior ofheat capacity, electrical resistivity, and attenuation of sound near
the critical point in the homogeneous phase.
In order to grasp an atomic scale phase separation from theliquid phase, neutron or x-ray diffraction experiments is one ofthe powerful tools. In this study, we tried to observe the structureof liquid Bi-Ga alloy by using the x-ray diffraction combinedwith the gas levitation and Laser heating.

mm was on the conical nozzle and heated by the focused
CO2 laser which is installed in the experiment hatch. The
temperature of sample was measured by using the single
color pyrometer. The temperature range of our experiments
was 505K~673K. The schematic view of experimental
apparatus is shown in Fig. 1.

Fig.1 Schematic figure of the gas-jet levitation for
the X-ray diffraction experiments
3. Result and Discussion
The structure factor is calculated from scattering
intensities obtained from the experiment. The graph in
Fig.2 shows structure factor at 535K of Bi-Ga liquid alloys
together with that of pure Bi and Ga.
8Bi100% (300℃),(4)Bi40%Ga60% (280℃)

2. ExperimentLiquid Bi-Ga alloy shows a phase separation with acritical point whose composition is Bi-70atmic%Ga andcritical temperature is 535K. The liquid Bi-Ga alloys shows
the homogeneous phase at the temperature higher than thecritical temperature. The homogeneous liquid alloy isseparated into two liquid phases, high density phase andlow density phase, at the temperature below the criticaltemperature.
In this study, the combination of X-ray analysis and jet
levitation method was tested to carry out the liquid
structure analysis of liquid-liquid phase separation system.
We used the two-axis diffractometer of BL04B2 in the
SPring-8. The high-energy X-ray (113.4 keV) was used forthe incident x-ray and the angular distribution of scattering
intensity was measured due to the Ge detector. The small
gas-jet levitation chamber was placed on the diffractometerand the levitated liquid sample was prepared for thediffraction experiments. The sample whose diameter was 2

S(Q)

6

Bi35%Ga65% (280℃)
Bi30%Ga70% (280℃)

4

Bi30%Ga70% (262℃)
Bi25%Ga75% (280℃)

2

Ga100% (550℃)
Ga100% ((200℃),(5)

0

2

4

6

8

10

Q(1/Å)

Fig.2 Structure factor of Bi-Ga liquid alloy
A small shoulder was observed in the high wave number
side of the first peak of S (Q). The small shoulder is also
observed in the structure factor of pure Bi and pure Ga. The
features of liquid structure of Bi and Ga were remainedeven in the liquid mixtures. Positions of first peak of S(Q)shifted to the low Q side when the concentration of Bi wasincreased.
In the near critical composition, the increase of scattering
intensity was observed at the low Q region (Q<0.5 Å -1),
which can be regarded as the increase of concentration
fluctuation. The relation between the liquid structure andcritical phase separation will be discussed in the poster
presentation.

－109－

P34
微小重力場低圧雰囲気における不等間隔燃料液滴列の燃え広がり特性の実験的調査○佐野成太，瀬尾健彦，三上真人（山口大）

Experimental Study on Flame-spread Characteristics of Fuel Droplet Arrays with Uneven
Droplet Spacing at Low Pressure in Microgravity○Narita SANO, Takehiko SEO , Masato MIKAMI (Yamaguchi Univ.)
1. Introduction
Spray combustion is widely used in gas turbine engines anddiesel engines. In order to elucidate basic flame spreadmechanisms, many researchers have investigated flame spreadof droplet arrays at normal pressure1)-3) and high pressures4) inmicrogravity. The droplet diameter is several μm order in spraycombustion, which is not affected by the natural convection. In
the experiment, it is necessary to use the droplet diameter of 1
mm order for observation with high resolution. In this case,however, the effect of the natural convection cannot be ignored
in normal gravity. Therefore, experiments have been carried out
in micro-gravity to ignore the effects of natural convection.
The fuel droplets distribute randomly in spray combustion.
Droplet spacing affects the characteristics of flame-spread.
Mikami et al2) experimentally investigated the flame-spread
limit distance between droplets at normal pressure in
microgravity. Oyagi et al.3) conducted flame-spread experimentin microgravity using droplet arrays with uneven droplet
spacing and reported that the flame-spread limit distanceincreases by two-droplet interactive combustion. The flamespread experiments of an n-decane droplet array were conductedin microgravity at pressures up to 5.0 MPa by Kobayashi et al4).
The effects of ambient pressure on flame spread phenomena
were investigated. However, the flame spread phenomena at low

Droplets I and B was SIB/d0 = 18 so that heat from the igniterdoes not affect to other droplets than Droplet I and theinteraction between burning Droplets I and B is negligible. The
initial droplet diameter d0 was estimated as 0.48 mm at theignition timing. Flame-spread behavior was recorded by adigital video camera. The framing rate of the camera was 240
fps. The low pressure atmosphere field was formed by removing
air from inside of the vessel by a vacuum pump. All theexperiments were conducted at 25 kPa in microgravity.
Microgravity conditions were attained by dropping theapparatus with a drag shield in the drop facility at the
Yamaguchi University, which provides about 0.95 s
microgravity conditions.

pressures have not been reported．This research experimentallyinvestigated flame-spread limit distance and flame-spread rateof fuel-droplet array with uneven droplet spacing in
microgravity at low pressure.

Fig. 1 Experimental apparatus

2. Experimental apparatus and method
Figure 1 shows the experimental apparatus. It consists of thedroplet generation system, the two-dimensional traverse system,
the ignition system and the low pressure vessel. The droplets areplaced at SiC fiber intersections1). The diameter of SiC fiber is
14 μm. The liquid fuel, n-decane, is supplied to intersections of
SiC fibers through a glass needle. The glass needle is connected
to a motor-driven micro-syringe through Teflon tube to supply
the fuel. The generated droplet diameter was 0.5 mm. Figure 2
shows the definition of the droplet array with uneven droplet
spacing. Droplet I is the droplet for ignition. Droplets A and B
are interactive droplets. Droplet L is the droplet to investigate
the flame-spread characteristics. The Droplet I was ignited by a
hot-wire igniter made of Fe-Cr. The droplet spacing between

Fig. 2 Droplet-array model

3. Results and discussion
Figure 3 shows direct images of flame-spread behavior of
fuel-droplet array for SBA/d0 = 4.2 and SAL/d0 = 27.1 at 25 kPa.
Figure 4 shows direct images of flame-spread behavior for
SBA/d0 = 4 and SAL/d0 = 16 at 101 kPa. These values of SAL/d0 are
near the flame-spread limit distance for each pressure. In Fig. 3,
blue flame was always observed through combustion at 25 kPa.

－110－

This indicates the soot formation was suppressed. However, atand A. ○ symbol represents the droplet spacing SAL/d0 if the

101 kPa, yellow luminosity from emission of soot was observed.
Elapsed time t/d02 is from the ignition of Droplet A. The initial
flame around Droplet L was observed at t/d02 = 1.83 s/mm2 andflame-spread rate was calculated as Vfd0 = 25.0 mm2/s at 25 kPa.
On the other hand, the initial flame around Droplet L wasobserved at t/d02 = 0.88 s/mm2 and flame-spread rate wascalculated as Vfd0 = 21.6 mm2/s at 101 kPa. The flame-spreadrate at 25 kPa is faster than at 101 kPa although the flamespread limit distance at 25 kPa is larger than that at 101 kPa.

flame-spread occurred, △ symbol represents SAL/d0 if theprobability of flame-spread occurrence was from 25% to 75%,
and × symbol represents SAL/d0 if the flame spread did not occur
at 25 kPa.□ symbol represents the droplet spacing SAL/d0 if theflame-spread occurred, + symbol represents SAL/d0 if the flame
spread did not occur at 101 kPa reported by Oyagi et al3). The
flame-spread-limit distance (SAL/d0)limit exists between ○ and×. Those results show the flame-spread-limit distance at 25 kPa
is greater than that at 101 kPa.
Figure 6 shows the relationship between flame-spread
distance and flame-spread rate. ◇ symbol shows the flamespread rate without interactive effect calculated from flamespread time and droplet spacing between Droplet B and A. △symbol shows the flame-spread rate in interactive condition of
SBA/d0 = 4.2. Considering the fact that the flame-spread rate
decreases with increasing the flame-spread distance2), Fig. 6
suggests that the flame-spread rate increases with interactive
effect of two droplets at 25 kPa.

t/d02 = 0 s/ mm2
t/d02 = 1.83 s/ mm2Fig. 3 Flame-spread behavior at 25 kPa

t/d02 = 0 s/ mm2

Flame-spread rate Vfd0 [ mm2/s ]200

t/d02 = 0.88 s/ mm2Fig. 4 Flame-spread behavior at 101 kPa

34
30

SAL/d0▲S160/d0=4.2

BA

120
80
40
0

0

4

8

12

16
S/d0

20

24

28

32

Fig. 6 Relationship between flame-spread distance and flamespread rate

26
22

4. Conclusions

18

This research experimentally investigated flame-spread-limit
distance and flame-spread rate of fuel-droplet-array with unevendroplet spacing in microgravity at low pressure.

14
10◆without interactive effect

0

4

8

12
SBA/d016

20

24

Fig. 5 Dependences of local flame-spread limit distance on thedroplet spacing SBA/d0 for interactive two droplets. The
data in the lower half part are for 101 kPa3) and the datain the upper half part are for 25 kPa.
Figure 5 shows the local flame-spread-limit distance ofdroplet array with two-droplet interaction between Droplets B(1) The flame-spread-limit distance at 25 kPa is greater than thatat 101 kPa.
(2) The flame spread rate increases with interactive effect of two
droplets at 25 kPa.

Acknowledgments
This research was partly subsidized by Grant-in-Aid for
Scientific Research (B) (24360350). We wish to thank Mr. N.
Motomatsu for his valuable help in experiments.

－111－

3)

References1)

spread probability and local interactive effects in randomly

M. Mikami ， H. Oyagi ， N. Kojima ， M. Kikuchi ， Y.

arranged fuel-droplet arrays in microgravity”，Combustion andWakashima ， S. Yoda ， “Microgravity experiments on flame
spread along fuel-droplet arrays using a new droplet-generation
technique”，Combustion and Flame，141,(2005)，241-252.
2)

H. Oyagi ， H. Shigeno ， M. Mikami ， N. Kojima ， “Flame-

Flame，156,(2009),763-770.
4)

M. Mikami, H. Oyagi, N. Kojima, M. Kikuchi, Y. Wakashima, S.
Yoda, “Microgravity experiments on flame spread along fueldroplet arrays at high temperatures”, Combustion and Flame，
146,(2006),391-406.

－112－

H.Kobayashi, J Park, T Iwahashi, T Nioka, “Micorgravity
experiments on flame spread of n-decane droplet array in a highpressure environment”, Proceedings of the Combustion Institute,29, (2002), 2603–2610.

P35
雰囲気酸素分圧依存性を考慮した銅および銀融体の無容器表面張力測定○西村大，武井悠翔，工藤優，小澤俊平（千葉工大）

Containerless Measurement of Surface Tension of Molten Copper and Silverin Consideration of Oxygen Partial Pressure of Atmospheric Gas○Masaru NISHIMURA, Yuto TAKEI, Yu KUDO, Shumpei OZAWA (Chiba Inst. Tech.)
1. Introduction
Surface tension of high temperature molten metals is one of
the most important thermophysical properties to improve andoptimize various high temperature melt processes involving afree surface such as welding and blazing, because surface
tension difference is a driving force of the Marangoni
convection.
It is known that oxygen acts as strong surfactant for molten
metals. Because oxygen can exist as gas phase even at room
temperature, surface tension of molten metals is influenced byoxygen partial pressure of measurement atmosphere, Po2 1),2).
However little attention has been given to the influence of Po2
on surface tension of molten metals. A conventional container
technique of the surface tension measurement such as the sessile
drop method can only assure the measurement at acomparatively low temperature in order to prevent a chemical
reaction between the sample and the measurement device.
In this study, surface tension of molten copper and silver wasmeasured by oscillating droplet method using electromagnetic
levitation (EML) free from container. Po2 of the atmosphericgas was controlled by gas phase equilibrium using H2-H2O
mixtures. The purpose of this study was to measure an accurate
surface tension of molten copper in consideration of influenceof Po2.
2. Experimental procedure
High purity cubical copper was electromagnetically levitated
and then melted under flow condition of the Ar-He-H2-H2Omixed gas. The Po2 of the inlet gas was confirmed by zirconia
oxygen sensor operated at 1008 [K]. The sample temperature
was controlled by flow ratio of argon and helium gases. The
surface tension of the sample was calculated from the droplet
oscillations using the Rayleigh equation 3) calibrated by
Cummings and Blackburn 4). The details of the experimental
procedure is shown elsewhere 2).

3. Results
Figure 1 shows the surface tension of molten copper
measured by oscillating droplet method using EML. We
successfully measured surface tension of molten copper over a
very wide temperature of about 500K under well controlled Po2
conditions. When the Po2 is less than 10-8 Pa below 1840 K

under the Ar-He-10vol.%H2 gas atmosphere, the surface tension
is decreased with increasing temperature. When the Po2 isprecisely controlled at 10-8, 10-7 and 10-6 Pa under the gas
equilibrium using Ar-He-H2-H2O mixtures, the boomerang
shape temperature dependence of surface tension for molten
copper is observed: the surface tension increases once and thendecreases with rising the temperature as in the case of molten
iron and nickel2),5). This boomerang shape temperaturedependence of surface tension can be explained by thetemperature reliance of equilibrium constant for oxygen
adsorption reaction. Higher Po2 usually induces lower surface
tension due to oxygen adsorption at comparatively low
temperature. However oxygen is desorbed from the melt surface
with increasing temperature because the equilibrium constant ofoxygen adsorption reaction decreases as the sample temperaturerises. In this case, the surface tension approaches to the purestate value. Consequently, the surface tension becomes almost
the same as the surface tension of pure state at high temperature.

M.P.1356K

Fig. 1 Surface tension of molten copper

References
1)

K. Mukai, Z. Yuan, K. Nogi, T. Hibiya: ISIJ Inter., 40, (2000)148.

2)

S. Ozawa, S. Suzuki, T. Hibiya, and H. Fukuyama: J. Appl. Phys.,109,(2010), 014902.

3)

Load Rayleigh: Proceeding of The Royal Society of London
29,(1879)71

4)

D. L. Cummings, D. A. Blackburn: J. Fluid Mech. 224, (1991)395.

5)

S. Ozawa, S. Takahashi, and Y. Takei: IJST2013 abstract.

－113－

P36
微小重力場における二液滴の冷炎・熱炎発生位置の観測○米康太，岩本武尊，橋本英樹，森上修，村瀬英一（九州大）
野村浩司（日本大），菊池政雄（宇宙航空研究開発機構）

Observation of Locations of Cool-Flame and Hot-Flame Appearances
around a Fuel Droplet Pair in Microgravity○Kota YONE, Takeru IWAMOTO, Hideki HASHIMOTO, Osamu MORIUE,
Eiichi MURASE (Kyushu Univ.), Hiroshi NOMURA (Nihon Univ.), Masao KIKUCHI (JAXA)
1. Introduction

g 2).

As seen in Fig. 1, the results showed that smaller

inter-droplet distance, l, led to longer cool-flame ignition delay,cf, and shorter second induction time, 2, the duration between
cool-flame appearance and hot-flame appearance. The results
implied that the mutual cooling effect was dominant before
cool-flame appearance, while the effect of duplicated fuelsources was dominant after cool-flame appearance. Suchtendency is caused by the development of non-spherical
distributions of temperature and fuel concentration, and is
supposed to be related with the locations of cool-flame and hotflame appearances. In order to observe those locations, twodimensional observation was attempted with Michelsoninterferometer, which enables the detection of cool flame 3), andone data was obtained in g.

In this study, the locations ofcool-flame and hot-flame appearances were further sought in g,and the effect of l and ambient temperature, Ta, was examined.

Hot flame
Cool flame
Second inducion time

1

Ignition delay [s]It is well known from the studies on homogeneous gas
mixtures that two-stage ignition occurs for most hydrocarbon
fuels. In two-stage ignition, cool flame, which is induced by
the low-temperature oxidation reactions and has almost no lightemission, appears first, and then hot flame, which is induced by
the high-temperature oxidation reactions, appears. The twostage ignition has been experimentally observed even for
spontaneous ignition of n-alkane droplets 1), which indicatedthat spontaneous ignition of a fuel spray must be analyzed withattention to two-stage ignition behavior. Spontaneous ignitionof a fuel droplet in hot air has been studied by many researchers
as a fundamental study for fuel-spray ignition. An isolated
droplet is physically the simplest model of a fuel spray. If theeffect of buoyancy is negligible, the phenomenon is sphericallysymmetric, which simplifies the comparison between
experiments and theoretical or numerical analysis. However,there exists interaction between droplets in a fuel spray, and its
effect cannot be taken into account by an isolated droplet.
Droplet interaction is supposed to have two counteracting
effects. One is mutual cooling effect between droplets throughmultiplied heat sinks, and the other is enhanced fuel supply
through multiplied fuel sources. In order to investigate theeffect of the droplet interaction, spontaneous ignition of a fueldroplet pair was experimentally studied by the authors' group in

0.5

0
0

2

4

6

8

∞
10

Inter-droplet distance [mm]Fig. 1

Effects of inter-droplet distance on cool-flame and hotflame ignition delays and second induction time (ndecane, 1 mm droplet, 0.3 MPa, 650 K, g) 2)

2. Experimental Apparatus and Procedure
The experimental apparatus is composed of a high-pressurechamber，optical recording system and controlling system.
The high-pressure chamber contains an electric furnace, adroplet-pair suspender, a suspender driving device and a fuelsupplying device. The inner volume of the furnace is 41 mm
in diameter and 40 mm in height. The temperature inside thefurnace was controlled to be a desired value. The fuel droplets
were generated on the intersections of 14 m SiC fibers at room
temperature. The distance between the two droplet centers was
defined as l, and was 2 mm or 4 mm. Fuel was n-decane, andits normal boiling point is 447 K. Initial droplet diameter, d0,
was 10.05 mm.

The droplet pair was inserted into the furnace,

which was located over the pair, and thus exposed from room
temperature to high temperature rapidly. The transition timefrom room temperature to high temperature was about 50 ms.
He-Ne laser (wave length: 633 nm, power: 0.84 mW) was used
as a light source of Michelson interferometer. The laser beam
was expanded to 20 mm in diameter and led into the furnace
through the windows. The direction of the laser beam was－114－

(a) 50 ms(b) 588 ms

1

1

-1
-2

-1
-2

(b) hot flame(a) cool flame
Fig. 3 Locations of cool-flame and hot-flame appearances(P=0.3 MPa, Ta=620 K, l=4 mm, fuel: n-decane,d0=1 mm, g)

650K

3

3

700K

700K

1

1

-1
(c) 598 ms

-3

-1

650K
620K

(a) cool flame

620K

-3
(b) hot flame

Fig. 4 Locations of cool-flame and hot-flame appearances
for different Ta (P=0.3 MPa, l=2 mm, fuel: ndecane, d0=1 mm, g) Temperatures in the figuresindicate Ta.
(d) 615 ms

perpendicular to the plane containing two droplets. Thus,
density distribution in the furnace was able to be qualitatively
observed as fringes. The images were recorded by a highspeed camera with a frequency of 1000 fps. Ambient pressure,P, was 0.3 MPa, and Ta was between 620 and 700 K. The drop
tower “COSMOTORRE” (g duration: 2.5 s) of HASTIC(e) 780 ms(Hokkaido Aerospace Science and Technology Incubation
Center) was used as microgravity facility.

3. Results and Discussion(f) 784 ms(g) 787 ms

Fig. 2 Images of spontaneously igniting droplet pairthrough interferometry (P=0.3 MPa, Ta=620 K,
l=4 mm, fuel: n-decane, d0=1 mm, g, 1000 fps)

Figure 2 shows the images abstracted from the movie for
Ta=620 K and l=4 mm. The droplet pair ended its travel into
the furnace at Fig. 2 (a) 50 ms. Then fuel vapor layer
developed around the droplet pair quasi-steadily until Fig. 2 (b)588 ms. Almost axial symmetric fringes show that temperature
distribution was also almost axial symmetric. There was achange in fringes at right down side of the right droplet in Fig. 2(c) 598 ms, which shows that there was a heat release by cool
flame. The fringes shifted towards two droplets (Fig. 2 (d) 615ms), which shows that cool flame was going to surround thedroplet pair. Then quasi-steady state lasted again until Fig. 2(e) 780 ms. In Fig. 2 (f) 784 ms and (g) 787 ms, sudden andnarrow change in fringes was observed in the middle point of
two droplets, which shows that there was a heat release by hot
flame. The locations of cool-flame and hot-flame appearances
obtained from Fig. 2 are shown in Fig. 3. Two circles filledwith gray color show two droplets, and unfilled ellipse or circle
shows the location of cool-flame or hot-flame appearance.
Scale of the coordinate is in mm. Location of cool-flame－115－

appearance is not as apparent as that of hot flame, and therefore
its location is wider. Such measurements were performed forseveral Ta at l=2mm, and the locations of cool-flame and hotflame appearances are shown in Fig. 4. Temperatures near
ellipses or circles show Ta. For all Ta, cool flame appeared on
the outer side of the droplet pair, and hot flame appeared on theplane located in the middle of two droplets. The previous
study 2) implied that temperature is dominant for cool-flame
appearance. The present results correspond with the previous
study, since the temperature on the outer side of the droplet pairis higher. The previous study 2) also implied that fuelconcentration is dominant for hot-flame appearance. The
present results also correspond with the previous study, since
the fuel concentration on the inner side of the droplet pair ishigher that on the outer side.

References
1)

Japan), 17, 57 (2008) 22. (in Japanese)2)

O. Moriue, Y. Nishiyama, Y. Yamaguchi, H. Hashimoto and E.
Murase: Proc. Combust. Inst., 34 (2013) 1585.

3)

4. Conclusions
In order to study the droplet interaction in spontaneous
ignition of a fuel spray, spontaneous ignition of a fuel droplet
pair was observed with interferometer in g.

O. Moriue and M. Tanabe: Atomization (Journal of the ILASS-

Cool flame

appeared on the outer side of the droplet pair, and hot flame
appeared on the inner side of the droplet pair. The resultscorrespond with the discussion in the previous study on thedevelopment of non-spherical distributions of temperature andfuel concentration.
Further examination for wider
experimental conditions are expected.

－116－

O. Moriue, R. Takagi, K. Yone, H. Hashimoto, E. Murase, K.
Kaneko, H. Nomura and M. Kikuchi: Trans. JSASS Aerospace
Tech. Japan, 12, ists29 (2014) pp. Ph_13.

P37
荷電コロイドの電荷誘起結晶化と結晶構造○柿原千穂，豊玉彰子，奥薗透，山中淳平（名古屋市立大学），
篠原忠臣，谷川正幸，曽我見郁夫（京都産業大学）

Charge-Induced Crystallization and Crystal Structures of Ionic Colloids○ Chiho KAKIHARA, Akiko TOYOTAMA, Tohru OKUZONO, Junpei YAMANAKA (Nagoya City Univ.),
Tadatomi SHINOHARA, Masayuki TANIGAWA, Ikuo SOGAMI (Kyoto Sangyo Univ.)

1. Introduction
Submicron-sized charged colloidal particles dispersed inliquid medium self-assemble into ordered “crystal” structures,
where the particles are regularly arranged in the body-centeredcubic (bcc) or face-centered-cubic (fcc) lattices. We have been
studying the charge-induced crystallization of dilute charged
colloids (1-4) in the Space Experiment Project on Colloidal
Crystallization (Director: Professor Emeritus Ikuo Sogami,
Kyoto Sangyo University). In the present paper we report the
bcc/fcc structural phase transition of the charged colloids uponincreasing the particle concentration and varying the charge
number.

showed the bcc to fcc transition at the lower particle
concentrations. Comparisons between the Kossel diffraction
measurements and reflection spectrum will be presented.

2. Materials and Methods
Polystyrene (PS) spheres were prepared by using anemulsion-free radical polymerization method. The reaction
solution (water/methanol mixtures) containing styrene(monomer), sodium p-styrenesulfonate (charged monomer),divinylbenzene (cross-linker),and potassium persulfate(polymerization initiator) were stirred at 80 ℃ under anitrogen atmosphere. Three kinds of particles, KSS-5 (thediameter d = 118 nm; charge number Z = 1245), KSS-6 (d = 109
nm; Z = 1233), and KSS-8 (d = 117 nm; Z = 1911) weresynthesized.
Reflection spectrum of the crystals were measured by using
fiber optics spectrophotometers USB2000 and NIR-512, Ocean
Optics Co., Ltd. Laser diffraction measurements were performedby means of Kossel diffraction apparatus constructed in Kyoto
Sangyo University.

Fig.1 Variations of diffraction wavelengths from colloidal
crystals upon changing the particle concentration
determined by using reflection spectrum (a) KSS-5 and (b)KSS-6. Symbols, observed wavelengths; curves, calculated
values for bcc (dash-dotted) and fcc (solid) crystals.

3. Results and Discussion
Figure 1 (a) and 1(b) show the diffraction wavelength ofthe KSS-5 and 6 samples. The symbols are observed values(filled square, open square, and open circles show the first,
second, and third diffractions, respectively). The solid and dotdashed curves represent calculated values for fcc and bcc
lattices. It is clearly seen that the crystal exhibited the phasetransition from bcc to fcc lattice structure on increasing theparticle concentration for both the samples.
We observed that the colloid having higher surface Z

References
1)
2)
3)
4)

－117－

J.Yamanaka, T.Koga, N.Ise, and T. Hashimoto, Phys.Rev.
E 53(1996) R4317.
J.Yamanaka, H.Yoshida, T.Koga, N.Ise, and T.Hashimoto,Phys. Rev. Lett., 80(1998) 5806.
H.Yoshida, J.Yamanaka, Ta.Koga, Ts.Koga, N.Ise, andT.Hashimoto, Langmuir, 15(1999)2684.
A . To y o t a m a , T. S a w a d a , J . Ya m a n a k a , K. Ki t a m u r a ,Langmuir, 19(2003) 3236.

P38
燃焼限界統一理論の構築に向けた微小重力場における極低速予混合対向流実験○小林友哉，中村寿，高瀬光一，手塚卓也，長谷川進（東北大），丸田薫（東北大，極東連邦大），Roman FURSENKO，Sergey MINAEV（極東連邦大），勝田真登，菊池政雄（JAXA）

Low-speed Premixed Counterflow Experiments under Microgravity for a Comprehensive
Combustion Limit Theory○Tomoya KOBAYASHI, Hisashi NAKAMURA, Koichi TAKASE, Takuya TEZUKA, Susumu HASEGAWA(Tohoku Univ.), Kaoru MARUTA (Tohoku Univ., Far Eastern Federal Univ.), Roman FURSENKO,
Sergey MINAEV (Far Eastern Federal Univ.), Masato KATSUTA, Masao KIKUCHI (JAXA)
1. Introduction

3. Results

Due to recent demand for higher efficiency combustors, theoxy-fuel combustion is drawing attention. The oxy-fuelcombustion uses fuel, pure oxygen, and recirculated CO2 inburned gas. To develop such combustors, an accurate and acomprehensive understanding of combustion limits with highconcentrations of CO2 is needed. In past studies, combustion
limits of flames have been investigated based on the

Figure 1 shows the flame obtained in the microgravity
experiments for CO2 diluted mixtures at the mixture velocity of
4.8 cm/s (stretch rate = 3.2 s-1) at the burner outlet. Initially, theflames are twin planar flames. Then, as the equivalence ratio isdecreased, the flame forms a single planar flame. Finally, atransition to a ball-like flame was observed before extinction.
This indicates that, similarly to Xe diluted mixtures, transition
from planar propagating flames to ball-like flames and then toflame balls may occur. For CO2 diluted mixtures, ball-likeflames were observed from equivalence ratio 0.49 to 0.48,
whereas for Xe diluted mixtures, ball-like flames were observed
from equivalence ratio 0.37 to 0.35. It can be observed that theequivalence ratio range is both narrow and at a higher region forCO2 mixtures than Xe for diluted mixtures. This is a result of thedifference in Lewis number and the amount of radiative heatloss.

counterflow method under g to rule out the effect of naturalconvection 1). However, parallel studies to this have revealed theexistence of non-propagating spherical flames, flame balls,
beyond the limit of planar propagating flames2). Since both ofthese flames have been investigated separately, there are only
limited attempts to bridge the limits of these two flames. For
discussion on absolute combustion limits, a theory thatencompasses both of these flames is required.
A recent study utilizing the counterflow method under g forTimeextremely low stretch rates with CH4/O2/Xe mixtures havesucceeded in obtaining a transition from planar flames to balllike flames3). However, the effect of radiation on the transitionand on combustion limits has not been investigated. Therefore,
the goal of this research is to provide a benchmark data
connecting counterflow flames and flame balls, and to provide
an understanding on the effects of radiation on the combustion
limits for the development of oxy-fuel combustors.

f = 0.54

f = 0.50

f = 0.49

Fig. 1 Images of experimental counterflow flames at 4.8 cm/s.

4. References
2. Experimental Method
Counterflow experiments under microgravity were conductedon the airplane MU-300 provided by the Diamond Air Service
Inc. Two opposing burners with an inner diameter of 3.0 cm andseparation distance of 3.0 cm were used inside a chamber toobtain the counterflow field. To observe the flame, a high-speed
camera equipped with an image intensifier was used. The
employed mixture is CH4/O2/CO2 where the ratio of O2 to CO2mole fraction is 0.4. Previous studies with Xe diluted mixtures
for the same setup have been conducted to obtain low-Lewis
numbers, showing that if the stretch rate is low enough, atransition from planar flames to ball-like flames will occur3).
Here, a Lewis number is the ratio of the diffusion and the heatdiffusion coefficients.

1)

K. Maruta, M. Yoshida, Y. Ju and T. Niioka: Proc. Combust. Inst.,
26 (1996) 1283.

2)

P. D. Ronney, M. S. Wu, H. G. Pearlman, K. J. Weiland: AIAA
Journal, 36 (1998) 1361.

3)

K. Takase, X. Li, J. Nakamura, T. Tezuka, S. Hasegawa, M.
Katsuta, M. Kikuchi, K. Maruta: Combust. Flame, 160 (2013)1235.

5. Acknowledgements
A part of this study was supported by JAXA and JSF by thelatter half of the second utilization phase of the KIBO
pressurized module project. Also, a part of this study was
supported financially by the Ministry of education and scienceof Russian Federation (project 14.Y26.31.0003).

－118－

P39
溶融塩中での月土壌シミュラントからの金属採取○坂中佳秀，後藤琢也（同志社大），石川毅彦，高柳昌弘（JAXA），福中康博（JST）

Extraction of Metal in Molten Salt from Lunar Regolith Simulant○Yoshihide SAKANAKA, Takuya GOTO (Doshisha Univ.) , Takehiko ISHIKAWA,
Masahiro TAKAYANAGI (JAXA), Yasuhiro FUKUNAKA (JST-CREST)
1. Introduction

3. Results

Considering the construction of lunar base, the high cost oftransporting materials from Earth to the Moon is important
problem. Therefore, in situ resource utilization is a key
component of space exploration. Because of the high cost oftransporting material from Earth to the Moon, we need to use
lunar resource to make all components. If silicon and othermetals could be produced on the moon, it would provide someadvantages.
Lunar crust is known to be rich in mineral resources, forexample, lunar regolith contains metallic elements such as
silicon, titanium, aluminum and so on. For using the mineral
resources, development for extracting process of the minerals isessential. From the background, electrochemical extraction ofsilicon and other metal in molten salts dissolved silica or lunar
regolith simulant has been proposed and experimentallydemonstrated.
MOx→M2x++xO2In this presentation, the electrochemical behavior of SiO2 andlunar regolith simulant in molten salt and property of obtained
samples will be presented.

In order to investigate the electrochemical behavior of lunar
regolith simulant, cyclic voltammetry was conducted in a
molten LiF-KF-BaF2 at 873 K.
Fig. 1 shows the cyclic voltammograms for Ni electrode before
and after addition of lunar regolith simulant. The dotted curve
presents the before and the solid curve presents the after
addition of lunar regolith simulant.
After addition of lunar regolith simulant, on the cathodic
sweep, a cathodic current was observed at approximately 1.0 V.
This cathodic current is attributed to metal deposition as shownin reaction (1)Mn++ne-→M (1)Based on the results of cyclic voltammetry, Ni plate was usedas the cathode and potentiostatic electrolysis was carried out at
0.2 V for 1 h in LiF-KF-BaF2 containing lunar regolith simulant
at 873 K.
From the result of XRD analysis of the sample, the observed
peaks were identified as Ni, originating from the substrate, Si
and Ni31Si12. Further analysis was conducted to investigate theelements of the sample. From the EDS analysis, obtained
sample containing Si, Ti and Al.

2. Experimental
All experiments were performed in LiF-NaF-KF or LiF-KFBaF2 eutectic melts in dry argon atmosphere. The cell was
alumina crucible in a cylindrical vessel made of refractory steel
and closed by a stainless steel lid. The cell was heated using a
programmable furnace and temperature was measured using achromel-alumel thermocouple.
SiO2 or lunar regolith simulant were added directly to themelts as silicon or metal ion source respectively. For theinvestigation of electrochemical behavior, Ag and Ni wire wereused as working electrode. A potentiostat/galvanostat (Hokuto
Denko Co. Ltd. HZ-3000) was used for electrochemicalmeasurements.
The samples were prepared by potentiostatic electrolysis andrinsed with AlCl3 solution. The obtained samples werecharacterized by X-ray diffraction. Morphologies of samples
were observed by scanning electron microscope.

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