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ABSTRACT: The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to
predict the onset of oscillatory thermocapillary convection. The experimental studies in the microgravity conditions on floating
half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing
aspect ratio, and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones
of several millimeters in diameter. In the present work, terrestrial experimental studies were conducted on the floating half
zones of 5 Centistokes (cSt) silicon oil and 10 cSt silicon oil. The experimental results show that the critical Marangoni
number generally increases with the increasing aspect ratio of the floating half zone and then decreases. Moreover, a further
increase of the critical Marangoni number with the increasing aspect ratio occurs for the slender floating half zones.
Keywordsthermocapillary convection–flow instability–aspect ratio
Science China: Physics, Mechanics and Astronomy 04/2012; 54(2):338-341. · 0.78 Impact Factor
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ABSTRACT: In the present paper, a liquid (or melt) film of relatively high temperature ejected from a vessel and painted on the moving
solid film is analyzed by using the second-order fluid model of the non-Newtonian fluid. The thermocapillary flow driven by
the temperature gradient on the free surface of a Newtonian liquid film was discussed before. The effect of rheological fluid
on thermocapillary flow is considered in the present paper. The analysis is based on the approximations of lubrication theory
and perturbation theory. The equation of liquid height and the process of thermal hydrodynamics of the non-Newtonian liquid
film are obtained, and the case of weak effect of the rheological fluid is solved in detail.
Science in China Series A Mathematics 04/2012; 45(9):1171-1182. · 0.70 Impact Factor
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ABSTRACT: Experimental studies have been performed for horizontal two-phase air-water flows at normal and reduced gravity conditions
in a square cross-section channel. The experiments at reduced gravity are conducted on board the Russian IL-76 reduced gravity
airplane. Four flow patterns, namely bubble, slug, slug-annular transition and annular flows, are observed depending on the
liquid and gas superficial velocities at both conditions. Semi-theoretical Weber number model is developed to include the
shape influence on the slug-annular transition. It is shown that its prediction is in reasonable agreement with the experimental
slug-annular transition under both conditions. For the case of two-phase gas-liquid flow with large value of the Froude number,
the drift-flux model, can predict well the observed boundary between bubble and slug flows.
Science in China Series E Technological Sciences 04/2012; 44(5):553-560. · 1.02 Impact Factor
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ABSTRACT: In 1999, the space experiments on the Marangoni convection and thermocapillary convection in a system of two immiscible liquid
layers in microgravity environment were conducted on board the Chinese scientific satellite SJ-5. A new system of two-layer
liquids such as FC-70 liquid and paraffin was used successfully, with the paraffin melted in the space. Two different test-cells
are subjected to a temperature gradient perpendicular or parallel to the interface to study the Marangoni convection and thermocapillary
convection, respectively. The experimental data obtained in the first Chinese space experiment of fluid are presented. Two-dimensional
numerical simulations of thermocapillary convections are carried out using SIMPLEC method. A reasonable agreement between
the experimental investigation and the numerical results is obtained.
Science in China Series E Technological Sciences 04/2012; 45(5):552-560. · 1.02 Impact Factor
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ABSTRACT: Results from a space experiment on bubble thermocapillary migration conducted on board the Chinese 22nd recoverable satellite
were presented. Considering the temperature field in the cell was disturbed by the accumulated bubbles, the temperature gradient
was corrected firstly with the help of the temperature measurement data at six points and numerical simulation. Marangoni
number (Ma) of single bubble migrating in the space experiment ranged from 98.04 to 9288, exceeding that in the previous experiment
data. The experiment data including the track and the velocity of two bubble thermocapillary migration showed that a smaller
bubble would move slower as it was passed by a larger one, and the smaller one would even rest in a short time when the size
ratio was large enough.
Science in China Series G Physics Mechanics and Astronomy 04/2012; 51(7):894-904. · 1.41 Impact Factor
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ABSTRACT: Microgravity fluid physics is an important part of microgravity sciences, which consists of simple fluids of many new systems,
gas-liquid two-phase flow and heat transfer, and complex fluid mechanics. In addition to the importance of itself in sciences
and applications, microgravity fluid physics closely relates to microgravity combustion, space biotechnology and space materials
science, and promotes the developments of interdisciplinary fields. Many space microgravity experiments have been performed
on board the recoverable satellites and space ships of China and pushed the rapid development of microgravity sciences in
China. In the present paper, space experimental studies and the main results of the microgravity fluid science in China in
the last 10 years or so are introduced briefly.
Chinese Science Bulletin 04/2012; 54(22):4035-4048. · 1.32 Impact Factor
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ABSTRACT: For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal
radiation (e.g. for atmosphere of O2−N2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere.
As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel
surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit
and absorb the thermal radiation (e.g. for atmosphere of O2−CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere
at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame
spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the
chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than
a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient
atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread
rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.
Science in China Series E Technological Sciences 04/2012; 46(4):381-390. · 1.02 Impact Factor
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ABSTRACT: A device of mercury liquid bridge of floating half-zone is designed to experimentally explore thermocapillary convection and
its instability of a low Prandtl number liquid. Noncontacted diagnostic techniques were developed to monitor surface flow
and surface deformation. The surface flow and the influence of a growing surface film (or skin) on the flow were observed.
It is shown that the film is a key factor in changing the behavior associated with the thermocapillary convection. The experiment
indicates that the critical Marangoni number should be much higher than that expected by the numerical simulation. The condition
and process of surface film growth are discussed. The surface oscillation of the mercury bridge wrapped with “dirt-film” was
observed, and the characteristics and the frequency associated with this oscillation are given.
Science in China Series E Technological Sciences 04/1997; 40(1):97-104. · 1.02 Impact Factor
