Experimental Assessment of Dynamic Surface Deformation Effects in Transition to Oscillatory Thermo capillary Flow in Liquid Bridge of High Prandtl Number Fluid (Dynamic Surf) - 01.31.17
The Dynamic Surf investigation is part of a series of JAXA experiments that Marangoni convection driven by the presence of surface tension gradient as produced by a temperature difference at a liquid/gas interface. Fluid convection observations of a silicone oil liquid bridge that is generated by heating the one disc higher than the other within the Fluid Physics Experiment Facility (FPEF). By observing and understanding how such fluids move researchers can learn about how heat is transferred in microgravity, and ultimately drive the design and development of more efficient fluid flow based systems and devices. Science Results for Everyone
Whole lotta shaking going on. This investigation created bridges between liquids to observe how fluids move in microgravity, where the absence of gravity allows formation of larger, longer bridges. Scientists observed large lateral motions of the liquid bridge and found two instances of shaking, each about a minute long. The liquid bridge did not move until several seconds after the second shaking instance, a longer time than expected. Installing a damper could prevent future shaking, helping preserve liquid bridges, and in turn allowing development of high-quality crystals. These crystals are used in various products such as semiconductors. Experiment Details
OpNom: Dynamic Surf
Yasuhiro Kamotani, Case Western Reserve University, Cleveland, OH, United States
Satoshi Matsumoto, Osaka City University, Osaka, Japan
Koichi Nishino, Yokohama National University, Yokohama, Japan
Atsuki Komiya, Tohoku University, Katahira, Japan
Masahiro Kawaji, University of Toronto, Toronto, Ontario, Canada
Nobuyuki Imaishi, Kyushu University, Katahira, Japan
Ichiro Ueno, Tokyo University of Science, Yamazaki, Japan
Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
IHI Aerospace Company, Ltd., Tomioka, Japan
Sponsoring Space Agency
Japan Aerospace Exploration Agency (JAXA)
Japan Aerospace Exploration Agency
Earth Benefits, Scientific Discovery
ISS Expedition Duration
March 2013 - March 2016; March 2016 - February 2017; March 2017 - September 2017
As for Marangoni experiment with liquid bridge configuration, the first and second series of Marangoni Experiments (MEIS-1, 2, 3, 4 & 5) were conducted in Increment 17, 20, 29, 25 and 32-34, respectively. And Marangoni UVPs (UVP-1&2) were performed in Increment 22-24 and 26-27, respectively. The liquid bridge size for MEIS-1, 2 & 3 was 30 mm in diameter and for UVP-1&2 was 50 mm. Marangoni Experiment -4&5 (MEIS-4&5) were used 50mm diameter liquid bridge. The same experiment cell as UVP-1&2 were employed for MEIS-4&5 but different experiment samples. The first series of Marangoni Experiment (MEIS-1) was the inaugural experiment for JAXA, which means it was the first scientific experiment in Kibo, and brought a lot of knowledge and experience.
The objective of scientific research on Marangoni convection utilizing microgravity is to make clear the flow transition phenomena from steady to oscillatory, chaotic, and finally turbulent flows. Therefore, it is important to understand an underlying principal of Marangoni convection. The findings and knowledge obtained through the space experiment is applied to industrial processes, as well as fluid physics.
JAXA has been carrying out four Marangoni experiments to fully understand Marangoni convection in microgravity on board the ISS. Fundamental questions regarding Marangoni Convection are as follows; (1) when and how are the onset of unsteady (or oscillatory) convection determined, (2) what are the characteristics of unsteady and three-dimensional flow, and temperature fields? (3) what are the mechanisms that are responsible for the formation of particle accumulation structures (PASs)? Answering these questions through the space experiments should contribute to the better understanding of Marangoni convection. The investigation is to be completed in 2016.
On the ground, only several millimeters of the liquid bridge can be seen, because the surface tension cannot support its own weight due to gravity. On the other hand, microgravity conditions provide some advantages: (1) Large and long liquid bridges can be formed, and (2) Pure and ideal Marangoni convection can be observed. As result, space experiments are expected to solve the whole picture of Marangoni convection. This directly contributes to the advancement of knowledge in the basic science of fluid physics. Moreover, the knowledge of Marangoni convection is useful in improving industrial processes such as the production of semiconductors, optical materials, bio materials, welding and micro/nano technologies, and in increasing the efficiency of thermal devices (i.e. heat pipe, evaporators/condensers).
Such a phenomenon is often observed in everyday life. For example, oil in a pan heated from center moves to peripheral side. Oil floating on water immediately moves when a surfactant (e.g. detergent) drops onto a part of the oil because of the imbalance in the surface tension. The detergent caused the center to have a lower surface tension. On the other hand, the outside has a higher surface tension, so the center and the oil were pulled out in all directions to equalize the surface tension. These phenomena are resulting from Marangoni effect.
Moreover, Marangoni convection affects the quality of grown crystal such as semiconductors, optical materials or bio materials. Therefore, it is important to understand an underlying principal and nature of Marangoni convection. The finding and knowledge obtained through space experiment is applied to industrial progression as well as advance of fluid dynamics. A liquid bridge configuration is often employed to investigate Marangoni convection because it is simulated a floating-zone method which is one of the crystal growth technique.
A liquid bridge (cylindrical liquid column) of silicone oil is formed into a pair of supporting solid disks. The convection is induced by imposing the temperature difference between disks, one end heating and other end cooling. Due to the convective instability, flow transits from laminar to oscillatory, chaos, and turbulence flows one by ones as the driving force increases. Scientists will observe the flow and temperature fields in each stage and investigate the flow transition conditions and processes. Fundamental questions regarding to Marangoni Convection are as follows;
- What are the conditions that determine the onset of unsteady (or oscillatory) convection in liquid bridge?
- What are the characteristics of unsteady, three-dimensional flow and temperature fields?
- What are the mechanisms that are responsible for the formation of dynamic particle accumulation structures (PASs)?
Why is the Marangoni experiment conducted on board the International Space Station (ISS)? On the ground, we can see the only several millimeters liquid bridge because surface tension cannot support its tare weight due to gravity. On the other hand, microgravity conditions provide us strong advantages as follows;
- Large and long liquid bridges can be formed.
- Therefore, high Marangoni numbers can be realized.
- No density-driven convection exists.
- No gravity-induced deformation of liquid bridge exists.
- Very long period for experiment can be allotted utilizing the ISS.
- Quite precise data with a wide range of parameters can be obtained by utilizing these merits in space.
In Dynamic Surf, Marangoni convection occurred in a liquid bridge is observed to make clear the flow transition phenomena resulting from a fluid instability. A silicone oil with a viscosity of 5 cSt(5 mm2/s), which is about five times higher one of water, is employed as working fluid and is suspended between a pair of solid disks (10mm in diameter). Small amount of fine particles is mixed into liquid bridge for flow visualization. One of the disks is heated and another cooled to impose temperature difference on both end of the liquid bridge. The temperature difference is gradually enlarged in order to increase the driving force of a thermocapillary flow (Marangoni flow). The flow transits from steady to oscillatory flow at the certain critical temperature difference. With increasing the temperature difference, the convection becomes more complicated toward turbulent via chaotic flows . These transition processes are observed in detail.
The Fluid Physics Experiment Facility (FPEF) mounted in Ryutai Rack inside KIBO Pressurized Module is used. The experiment is conducted in combining FPEF and an experiment unique hardware which is exchangeable according to the purpose of investigation and is called "Experiment Cell". A white and black CCD camera is mounted on the experiment cell to observe the flow patterns. And, Dynamic surface deformation (DSD) is measured using a microscopic imaging displacement meter (MIDM), which is newly-developed by science team. The hardware for MIDM, consisting of a monochromatic CCD camera, a microscopic lens, and a back illumination light source, is installed in the custom-built EC. FPEF equips Infrared Imager for temperature visualizations. An infrared imager is used to observe dynamic temperature distribution on the liquid bridge surface. Marangoni experiment also uses Image Processing Unit (IPU) and Microgravity Measurement Apparatus (MMA) with accelerometer to measure microgravity environment near the FPEF.
The valuable knowledge from the Marangoni space experiment is also applicable to the high performance heat exchangers and heat pipes both in space and on Earth. For future space development, it should be necessary to more efficient and compact thermal management system, no doubt to help its development.
The obtained knowledge on the Marangoni convection is vital for the production of high-quality crystal growth such as semiconductors, optical crystal so on. Since the surface tension is dominant not only under microgravity conditions, but also in the micro-scale, the results obtained on the nature of the Marangoni convection can significantly contribute to various micro-fluid handling techniques in micro-TAS (Micro total analysis system), such as DNA examination and clinical diagnostics.
Operational Requirements and Protocols
Decadal Survey Recommendations
Information Pending^ back to top
During the JAXA Dynamic Surf experiment, scientists saw large liquid bridge oscillations, where the bridge moved side to side. Sensors on the experiment's hardware did not detect any singular shaking that could cause the liquid bridge to move as it did. The scientists found a very small shaking incident with almost the same frequency as the resonance one, which caused the liquid bridge oscillations. They also looked at what the sensors detected before the liquid bridge shook, and saw that there had been two instances of shaking. Each lasted for about 1 minute. A couple of seconds after the second instance of shaking, the liquid bridge began to shake. The scientists revealed that it took an unexpected long time for the liquid bridge to shake as it did. They advised the possibility of installing a damper to prevent this shaking from happening. These results are important because preserving liquid bridges can help develop high-quality crystals. Products such as semiconductors can use these crystals.^ back to top
Ground Based Results Publications
Ferrera C, Herrada MA, Montanero JM. Analysis of a resonance liquid bridge oscillation on board of the International Space Station. European Journal of Mechanics - B/Fluids. 2016 May-June; 57: 15-21. DOI: 10.1016/j.euromechflu.2016.02.003.
Largest liquid bridge of silicone oil formed in Kibo.
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Observation method of Marangoni convection (MIDM: Microscopic Imaging Displacement Meter).
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