Recent Progress in the Studies of Gas-Liquid Two-Phase Flows at Microgravity Conditions

2003 ◽  
Author(s):  
Tomoji Takamasa ◽  
Takashi Hibiki
Keyword(s):  
Recent Progress ◽  
Interfacial Area ◽  
Phase System ◽  
Two Phase Flows ◽  
Two Phase ◽  
Interfacial Area Transport ◽  
Drift Flux ◽  
Wide Range ◽  
Microgravity Conditions ◽  
Heat Loads

In a thermal system of spacecraft, two-phase flow system now is an excellent alternative to the conventional single-phase system in transporting large amount of thermal energy at a uniform temperature regardless of variations in the heat loads. In addition, two-phase flows exist in a wide range of applications and enabling technologies in space. This report outlines recent progress in the studies of gas-liquid two-phase flows at microgravity conditions, especially for which regarding to interfacial area transport and drift flux.

Study on Drag Coefficients for Two Groups of Bubbles

2004 ◽  
Author(s):  
Xiaodong Sun ◽  
Yang Liu ◽  
Basar Ozar ◽  
Mamoru Ishii ◽  
Joseph M. Kelly
Keyword(s):  
Gas Phase ◽  
Fluid Model ◽  
Interfacial Area ◽  
Current Approach ◽  
Two Phase ◽  
Drag Coefficients ◽  
Interfacial Area Transport ◽  
Wide Range ◽  
Two Fluid Model ◽  
Two Fluid

To apply the two-fluid model to a wide range of flow regimes in gas-liquid two-phase flows, the gas phase is categorized into two groups: small spherical/distorted bubbles as Group 1 and large cap/slug/churn-turbulent bubbles as Group 2 in the modeling of interfacial area transport. The interfacial transfer terms of momentum and energy for the gas phase are then divided into two groups accordingly in the implementation of the two-group interfacial area transport equation to the two-fluid model. Thus, the drag coefficients and the interfacial heat transfer for each group bubbles need to be developed. An approach has been sought for evaluating the drag coefficients of each bubble group based on a comprehensive experimental data base obtained in air-water upward flows in various size round pipes. Comparisons have been made with the theory of the drag coefficients and it was found that the agreement is not very satisfactory although the general trends can be predicted by the current approach.

One-Dimensional Drift-Flux Model and Constitutive Equations for Relative Motion Between Phases in Various Two-Phase Flow Regimes at Microgravity Conditions

2004 ◽  
Author(s):  
Takashi Hibiki ◽  
Tomoji Takamasa ◽  
Mamoru Ishii
Keyword(s):  
Constitutive Equations ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Wide Range ◽  
Microgravity Conditions ◽  
Flux Model

In view of the practical importance of the drift-flux model for two-phase flow analyses at microgravity conditions, the constitutive equations for distribution parameter and drift velocity have been developed for various two-phase flow regimes at microgravity conditions. A comparison of the model with various experimental data over various flow regimes and a wide range of flow parameters taken at microgravity conditions shows a satisfactory agreement. The newly developed drift-flux model has been applied to reduced gravity conditions such as 1.62 and 3.71 cm/s2, which correspond to the Lunar and Martian surface gravities, respectively, and the effect of the gravity on the void fraction in two-phase flow systems has been discussed.

Activity coefficients, densities, dipole moments, and surface tensions of the system triethylamine–methylethylketone–water

1981 ◽  
Vol 59 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Alan N. Campbell
Keyword(s):  
Surface Layer ◽  
Dipole Moments ◽  
Phase System ◽  
Constant Composition ◽  
Two Phase ◽  
Three Phase ◽  
Wide Range ◽  
Isothermal System ◽  
Total Composition ◽  
Two Phases

The properties named in the title have been determined by standard methods. Viscosity, molar volume, and orientation polarisation all indicate abnormalities of the nature of association between the components.The most interesting result is that of surface tension which indicates that, in the case of the binary system triethylamine–water, a surface layer of constant composition is formed over a wide range of total composition. When, by a rise in temperature of two or three degrees, this layer becomes unstable, it splits into two phases of different composition. The surface layer may then be instantaneously reformed and so on. A mechanism for the generation of a two-phase system is thus established. The data for the three-phase, isothermal, system are not so convincing, for reasons that are suggested.

The characterization of crystalline particle growth in TiNi thin films

2004 ◽  
Vol 37 (6) ◽  
pp. 1007-1009 ◽  
Author(s):  
Yonghua Li ◽  
Fanling Meng ◽  
Jinkuan Wang ◽  
Yuming Wang
Keyword(s):  
Interfacial Area ◽  
Particle Growth ◽  
Radius Of Gyration ◽  
Phase System ◽  
Crystalline Particle ◽  
Two Phase ◽  
X Ray ◽  
Specific Interfacial Area ◽  
Subsequent Decrease ◽  
Sputter Deposited

Small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) have been used to investigate sputter-deposited TiNi films annealed at 773 K for 3, 8, 13, 15, 25 and 60 min. The specific interfacial area of the crystalline–amorphous two-phase system increases at the beginning of annealing, achieves a maximum after about 13 min and decreases on further annealing, whereas the radius of gyration of the crystalline particle increases during the annealing process. The prominent increase of the specific interfacial area and the slight increase of the radius of gyration of the crystalline particle at the beginning of annealing are correlated with the nucleation of the crystalline particle. The subsequent decrease of the specific interfacial area is correlated with the growth of the crystalline particles.

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