Initiation and Statistical Evolution of Horizontal Slug Flow With a Two-Fluid Model

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
A. O. Nieckele ◽  
J. N. E. Carneiro ◽  
R. C. Chucuya ◽  
J. H. P. Azevedo
Keyword(s):  
Experimental Data ◽  
Slug Flow ◽  
Fluid Model ◽  
Subsequent Development ◽  
Complex Flow ◽  
Horizontal Pipes ◽  
Dimensional Version ◽  
Two Fluid Model ◽  
Log Normal ◽  
Two Fluid

In the present work, the onset and subsequent development of slug flow in horizontal pipes is investigated by solving the transient one-dimensional version of the two-fluid model in a high resolution mesh using a finite volume technique. The methodology (named slug-capturing) was proposed before in the literature and the present work represents a confirmation of its applicability in predicting this very complex flow regime. Further, different configurations are analyzed here and comparisons are performed against different sets of experimental data. Predictions for mean slug variables were in good agreement with experimental data. Additionally, focus is given to the statistical properties of slug flows such as shapes of probability density functions of slug lengths (which were represented by gamma and log-normal distributions) as well as the evolution of the first statistical moments, which were shown to be well reproduced by the methodology.

Initiation and Statistical Development of Slug Flow With a High Resolution Two-Fluid Model

2012 ◽  
Author(s):  
R. C. Chucuya ◽  
J. N. E. Carneiro ◽  
A. O. Nieckele
Keyword(s):  
High Resolution ◽  
Slug Flow ◽  
Fluid Model ◽  
Subsequent Development ◽  
Complex Flow ◽  
Mean Values ◽  
Horizontal Pipes ◽  
Dimensional Version ◽  
Two Fluid Model ◽  
Two Fluid

In the present work, the onset and subsequent development of slug flow in horizontal pipes is investigated by accurately solving the transient one-dimensional version of the Two-Fluid Model using a finite volume technique. Growth of disturbances that eventually bridge the pipe section is an automatic outcome of the solution of the discretized equations in a high resolution mesh, avoiding the need for the commonly used phenomenological models for the stratified to slug transition. Slug dynamics evolve naturally without the need of empirical correlations for slug parameters. This methodology (named “slug-capturing”) was proposed before in the literature and the present work represents a rare confirmation of its applicability in predicting this very complex flow regime. Here, different configurations are analyzed and comparisons are performed against different sets of experimental data. Additionally, statistical analysis of the slug parameters is performed and it is shown through comparisons against experimental measurements that this methodology is able not only to provide mean values of e.g. slug and bubble lengths and their evolution inside the pipe, but also shapes of probability density functions (PDFs), with a good degree of accuracy.

Review of Applicability of the One-dimensional Two-fluid Model to the Prediction of Wave Growth and Slug Evolution in Horizontal Pipes

2010 ◽  
Author(s):  
Raad I. Issa ◽  
Liejin Guo ◽  
D. D. Joseph ◽  
Y. Matsumoto ◽  
Y. Sommerfeld ◽  
...  
Keyword(s):  
Fluid Model ◽  
Wave Growth ◽  
One Dimensional ◽  
Horizontal Pipes ◽  
Two Fluid Model ◽  
The One ◽  
Two Fluid

scholarly journals A CFD Study on Two-Phase Frozen Flow of Air/Water Through a Safety Relief Valve

2015 ◽  
Vol 13 (4) ◽  
pp. 533-540 ◽  
Author(s):  
Moftah Alshaikh ◽  
William Dempster
Keyword(s):  
Fluid Model ◽  
Critical Mass ◽  
Velocity Slip ◽  
Flow Conditions ◽  
Complex Flow ◽  
Relief Valve ◽  
Two Phase ◽  
Mass Flows ◽  
Two Fluid Model ◽  
Two Fluid

Abstract The air-water two phase critical flows through a safety relief valve commonly used in the refrigeration industry is examined with particular emphasis on the prediction of the critical mass flowrates using CFD based approaches. The expansion of the gas through the valve and the associated acceleration is coupled to the liquid phase and results in changes to the velocity slip with the possibility of influencing the choking conditions and the magnitude of the critical mass flows. These conditions are poorly reported in the literature for safety valves. This paper presents a study where the ability of established two phase multi-dimensional modelling approaches to predict such conditions are investigated. Comparison with the simplified mixture model will show that this model tends to underestimate mass flowrates for medium to high liquid mass fraction. However, the two fluid model can adequately account for the thermal and mechanical non equilibrium for these complex flow conditions with the use of simplified droplet sizing rules.

Numerical Simulation of Effect of Internals on Slugging Fluidization and Analysis of Nonuniformity Index

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Xiaoling Wang ◽  
Liang Yu ◽  
Jun Wang
Keyword(s):  
Experimental Data ◽  
Granular Flow ◽  
Fluidized Beds ◽  
Fluid Model ◽  
Two Fluid Model ◽  
Reasonable Prediction ◽  
Two Fluid ◽  
Radial Nonuniformity ◽  
Flow Nonuniformity

Abstract The Two-Fluid Model (TFM) using the Kinetic Theory of Granular Flow (KTGF) was applied to simulate 3-D dense fluidized beds with different complex internals. The slugging fluidization was found in the simulated results. When the internals were placed into the reactors, the simulated results showed that the slugs were broken up and bubbling fluidization was formed instead of slugging fluidization. The formation, growth, size, and shape of bubbles were validated to ensure a reasonable prediction. Furthermore, the simulated pressure drop was compared with the corresponding experimental data from the dense fluidized beds with different complex internals, and good agreements were observed. Finally, the flow nonuniformity in the dense fluidized beds was evaluated by a developed method. This method extended Radial Nonuniformity Index (RNI) to Face Nonuniformity Index (FNI) and Volume Nonuniformity Index (VNI). From the calculated FNI and VNI, the fluidization quality of the fluidized beds was quantitatively judged as follows: No.3 > No.1> No.2 > No.4 > Without Internal.

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