Entrance Effects in a Two-Phase Slug Flow

1962 ◽  
Vol 84 (1) ◽  
pp. 29-38 ◽  
Author(s):  
R. Moissis ◽  
P. Griffith
Keyword(s):  
Slug Flow ◽  
Present Theory ◽  
Separation Distance ◽  
Rise Velocity ◽  
Two Phase ◽  
Developing Flow ◽  
Two Phases ◽  
Kinetics Of ◽  
Theory And Experiments ◽  
Good Agreement

This paper describes quantitatively one stage of the flow development process in equipment working with two-phase mixtures. The kinetics of a Taylor bubble, as it rises behind a series of other bubbles in a gas-liquid slug flow, have been determined. The rise velocity of a bubble is expressed as a function of separation distance from the bubble ahead of it. Using this information, the pattern of development of bubbles which initially enter a tube at regular intervals is determined by means of finite difference calculations. The density and, to a first approximation the pressure drop, of the developing flow are then calculated from continuity considerations. The density distribution in the entrance region is found to be a function of flow rates of the two phases, of distance from the inlet, and of initial bubble size. Density calculated by the present theory is compared with experimental measurements by the present and other investigators. Theory and experiments are in good agreement.

Phase Field Simulation of Coarsening Kinetics in Al-Sc and Al-Sc-Zr Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
H. Zapolsky ◽  
J. Boisse ◽  
R. Patte ◽  
N. Lecoq
Keyword(s):  
Phase Field ◽  
Diffusion Coefficients ◽  
Three Dimensional ◽  
Ternary Alloys ◽  
Simulation Results ◽  
Coarsening Kinetics ◽  
Two Phases ◽  
Kinetics Of ◽  
Good Agreement ◽  
Zr Alloys

AbstractThe coarsening kinetics of γ’ precipitates in binary and ternary Al3Sc1-xZrx alloys is studied by using the two- and three-dimensional phase-field simulations. Our focus is on the influence of diffusion coefficients of Sc and Zr atoms on the transformation path kinetics from disordered f.c.c. matrix to two phases equilibrium state with γ’ precipitates and f.c.c. disordered matrix. Our simulation results demonstrate that in the case of binary alloys taking into account the concentration dependence of the mobility of atoms decreases the coarsening rate. In the case of ternary alloys we show that the Al3Sc particles precipitate first following by appearance of a Zr-rich shell. Our simulations results are in good agreement with experimental observations.

Steam Slip—Theoretical Prediction From Momentum Model

1960 ◽  
Vol 82 (2) ◽  
pp. 113-124 ◽  
Author(s):  
S. Levy
Keyword(s):  
Two Phase ◽  
Forced Circulation ◽  
Channel Geometry ◽  
Pressure Drops ◽  
Head Losses ◽  
Heat Addition ◽  
Slip Effects ◽  
Two Phases ◽  
Vertical Test ◽  
Good Agreement

Theoretical equations governing slip effects in forced circulation of boiling water are derived. The equations indicate that steam slip is dependent upon channel geometry, inlet water velocity, and rate of heat addition. A simplified momentum model is postulated which leads to equal friction and head losses of two phases. The model gives good agreement with available experimental results in horizontal and vertical test sections with and without heat addition at pressures from 12 to 2000 psia. Discussion of the model in terms of nonquasi steady-state unbalances of friction and head losses of the two phases explains experimental deviations from the predictions and the previously noted effects of water inlet velocity. It also gives trends for the effects of channel geometry and rate of heat addition. Application of the simplified model to calculating two-phase pressure drops is included.

A NOVEL MODEL OF DIELECTRIC CONSTANT OF TWO-PHASE COMPOSITES WITH INTERFACIAL SHELLS

2002 ◽  
Vol 16 (25) ◽  
pp. 3855-3863 ◽  
Author(s):  
QINGZHONG XUE
Keyword(s):  
Dielectric Constant ◽  
Effective Dielectric Constant ◽  
Maxwell Theory ◽  
Two Phase ◽  
Random Composites ◽  
Polarization Theory ◽  
Two Phases ◽  
Novel Model ◽  
Theoretical Results ◽  
Good Agreement

Considering the interface effect between two phases in composite, we present a novel model of dielectric constant of two-phase composites with interfacial shells. Starting from Maxwell theory and average polarization theory, the formula of calculating the effective dielectric constant of two-phase random composites with interfacial shells is presented. The theoretical results on effective dielectric constant of alkyd resin paint/Barium titanate random composites with interfacial shells are in good agreement with the experimental data.

Deformation Microstructures in a Two-Phase Stainless Steel during Large Strain Deformation

2006 ◽  
Vol 503-504 ◽  
pp. 305-310
Author(s):  
Kaneaki Tsuzaki ◽  
Andrey Belyakov ◽  
Yuuji Kimura
Keyword(s):  
Stainless Steel ◽  
Cold Working ◽  
Large Strain ◽  
Deformation Behaviour ◽  
Large Strains ◽  
Transverse Size ◽  
Plastic Working ◽  
Two Phase ◽  
Two Phases ◽  
Kinetics Of

Deformation microstructures were studied in a two-phase (about 60% ferrite and 40% austenite) Fe – 27%Cr – 9%Ni stainless steel. Severe plastic working was carried out by rolling from 21.3×21.3 mm2 to 7.8×7.8 mm2 square bar followed by swaging from Ø7.0 to 0.6 mm rod at an ambient temperature, providing a total strain of 6.9. After a rapid increase in the hardness at an early deformation, the rate of the strain hardening gradually decreased to almost zero at large strains above 4. In other words, the hardness approached a saturation level, leading to an apparent steadystate deformation behaviour during cold working. The severe deformation resulted in the evolution of highly elongated (sub)grains aligned along the rolling/swaging axis with the final transverse (sub)grain size of about 0.1 μm and the fraction of high-angle (sub)boundaries above 60%. However, the kinetics of microstructure evolution in the two phases was different. In the ferrite phase, the transverse size of deformation (sub)grains gradually decreased during the processing and approached 0.1 μm at strains of about 6.0, while the transverse size of the austenite (sub)grains rapidly reduced to its final value of 0.1 μm after a relatively low strain about 1.0.

Modeling of Slug Dissipation and Generation in Gas-Liquid Hilly-Terrain Pipe Flow

2003 ◽  
Vol 125 (3) ◽  
pp. 161-168 ◽  
Author(s):  
Hong-Quan Zhang ◽  
Eissa M. Al-Safran ◽  
Subash S. Jayawardena ◽  
Clifford L. Redus ◽  
Cem Sarica ◽  
...  
Keyword(s):  
Pipe Flow ◽  
Slug Flow ◽  
Control Volume ◽  
Unit Length ◽  
Mineral Oil ◽  
Hilly Terrain ◽  
Two Phase ◽  
Oil Flow ◽  
Flow Experiences ◽  
Good Agreement

Hilly-terrain pipelines consist of interconnected horizontal, uphill and downhill sections. Slug flow experiences a transition from one state to another as the pipe inclination angle changes. Normally, slugs dissipate if the upward inclination becomes smaller or the downward inclination becomes larger, and slug generation occurs vice versa. Appropriate prediction of the slug characteristics is crucial for the design of pipeline and downstream facilities. In this study, slug dissipation and generation in a valley pipeline configuration (horizontal-downhill-uphill-horizontal) were modeled by use of the method proposed by Zhang et al. The method was developed from the unsteady continuity and momentum equations for two-phase slug flow by considering the entire film zone as the control volume. Computed results are compared with experimental measurements at different air-mineral oil flow rate combinations. Good agreement is observed for the change of slug body length to slug unit length ratio.

NUMERICAL SIMULATION ON TWO-PHASE BUBBLY FLOW SPLIT IN A BRANCHING T-JUNCTION

2011 ◽  
Vol 19 (04) ◽  
pp. 253-262 ◽  
Author(s):  
Y. LIU ◽  
W. Z. LI
Keyword(s):  
Model Simulation ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Three Dimensional ◽  
Two Phase ◽  
Flow Parameters ◽  
Two Phases ◽  
Inertia Difference ◽  
Two Fluid ◽  
Good Agreement

In this paper, a steady three-dimensional two-fluid computational fluid dynamics predictive model is presented to simulate the dispersed bubbly flow split phenomenon in a T-junction with 50 mm diameter for all arms. The fluid is treated as a mixture and the fundamental mass, momentum and turbulent equations are solved to account for the flow parameters, where the turbulence is modeled by the standard k − ε model. Simulation results imply that the gas phase inclines to flow into the side arm even for small extraction rate conditions, because the pressure difference of the side arm to inlet is much larger than that of run arm to inlet. The analysis of velocity field reveals that it is the inertia difference between the two phases that leads to the phase split phenomenon. The effect of bubble diameter on flow split is also investigated and it is found that split efficiency is greatly influenced by it. The computed solutions are compared with experimental data and a good agreement is achieved.

Velocity Distributions in Two-Phase Vortex Flow

1968 ◽  
Vol 90 (3) ◽  
pp. 368-372
Author(s):  
J. F. Lafferty ◽  
F. G. Hammitt ◽  
R. Cheesewright
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Vortex Flow ◽  
Single Phase ◽  
Gas Jet ◽  
Two Phase ◽  
Two Phases ◽  
Good Agreement

An analytical model is developed to describe gas-jet driven two-phase vortex flow. Utilizing experimental data, the model is used to calculate the velocity distributions of the two phases within an air-water vortex. The computed velocities are in very good agreement with independent measurements and with trends predicted from other investigations of single-phase vortex flow.

Modeling of Effective Stagnant Thermal Conductivity of Porous Media

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Yasuyuki Takatsu ◽  
Takashi Masuoka ◽  
Takahiro Nomura ◽  
Yuji Yamada
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Heat Conduction ◽  
Local Thermal Equilibrium ◽  
Two Phase ◽  
Spatially Periodic ◽  
Phase Systems ◽  
Multi Phase ◽  
Theory And Experiments ◽  
Good Agreement

Based on one-dimensional analysis of heat conduction, a general formula for the effective stagnant thermal conductivity of spatially periodic porous media is derived without assuming local thermal equilibrium. Furthermore, we discuss the contribution of the contact area between particles to the effective stagnant thermal conductivity in detail, and the modification of the formula is proposed to predict the actual effective stagnant thermal conductivity for the porous media. The present results are in good agreement with experimental results of Nozad et al. (1985, “Heat Conduction in Multi-Phase Systems I: Theory and Experiments for Two-Phase Systems,” Chem. Eng. Sci., 40(5), pp. 843–855) for a packed-sphere bed.

Mechanism of Slug Formation in Horizontal Two-Phase Flow

1970 ◽  
Vol 92 (4) ◽  
pp. 857-864 ◽  
Author(s):  
E. S. Kordyban ◽  
T. Ranov
Keyword(s):  
Theoretical Prediction ◽  
Surface Waves ◽  
Flow Pattern ◽  
Slug Flow ◽  
Wave Amplitude ◽  
Experimental Results ◽  
Phase Flow ◽  
Helmholtz Instability ◽  
Two Phase ◽  
Good Agreement

It is proposed in this work that the transition to slug flow occurs due to Kelvin-Helmholtz instability, which, in this case, is enhanced by the proximity of the upper wall and becomes wave-amplitude dependent. Since the surface waves possess a limiting amplitude, the transition can be predicted by examining whether the highest possible waves are unstable. The theoretical prediction is in good agreement with the authors’ experimental results. It also agrees reasonably well with Baker’s and Schicht’s flow pattern charts for strictly horizontal channels, but it exhibits large differences when the channels deviate somewhat from the horizontal.

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