Numerical Simulation of Turbulent Mist Flows With Liquid Film Formation in Curved Pipes Using an Eulerian–Eulerian Method

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Pusheng Zhang ◽  
Randy M. Roberts ◽  
André Bénard
Keyword(s):  
Pressure Drop ◽  
Liquid Film ◽  
Film Formation ◽  
Flow Patterns ◽  
Droplet Deposition ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Curved Pipes ◽  
Eulerian Method ◽  
Flux Model

Turbulent flows of air/water mixtures through curved pipes are modeled in this work using a Eulerian–Eulerian method. This is motivated by the possibility of using computational fluid dynamics (CFD) as a design tool applied to curved pipes feeding a gas/liquid separator. The question is to identify the curvature of such pipes that can promote film formation upstream of the separator and, thus, precondition the flow without creating a large pressure drop. The performance of the mixture theory with a drift flux model and the “realizable” k-ε closure was evaluated in the simulations. The enhanced wall treatment (EWT) was utilized to resolve the flow in the near-wall region. A qualitative study was first conducted to investigate the flow patterns and the liquid film formation in a 180 deg bend. The numerical results were validated by comparing the computed pressure drop with empirical correlations from the literature. Subsequently, the importance of droplet size and liquid volume fraction was investigated by studying their effect on the flow patterns of the continuous phase, as well as their impact on the secondary flow intensity, the pressure drop, and the liquid film formation on the wall. Various pipe geometries were studied to achieve a low pressure drop while maintaining a high droplet deposition. Results show that a combination of the drift flux model with the realizable k-ε closure and EWT for the near-wall treatment appears capable of capturing the complex secondary flow patterns such as those associated with film inversion. The pressure drop computed for various flows appear to be in good agreement with an empirical correlation. Finally, bends with a curvature ratio around 7 appear to be the optimal for providing a small pressure drop as well as a high droplet deposition efficiency in a U-bend.

Investigation of Holdup and Pressure Drop Behavior for Oil-Water Flow in Vertical and Deviated Wells

1998 ◽  
Vol 120 (1) ◽  
pp. 8-14 ◽  
Author(s):  
J. G. Flores ◽  
C. Sarica ◽  
T. X. Chen ◽  
J. P. Brill
Keyword(s):  
Pressure Drop ◽  
Water Flow ◽  
Flow Patterns ◽  
Production Optimization ◽  
Pressure Gradients ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Inclination Angles ◽  
Oil Water

Two-phase flow of oil and water is commonly observed in wellbores, and its behavior under a wide range of flow conditions and inclination angles constitutes a relevant unresolved issue for the petroleum industry. Among the most significant applications of oil-water flow in wellbores are production optimization, production string selection, production logging interpretation, down-hole metering, and artificial lift design and modeling. In this study, oil-water flow in vertical and inclined pipes has been investigated theoretically and experimentally. The data are acquired in a transparent test section (0.0508 m i.d., 15.3 m long) using a mineral oil and water (ρo/ρw = 0.85, μo/μw = 20.0 & σo−w = 33.5 dyne/cm at 32.22°C). The tests covered inclination angles of 90, 75, 60, and 45 deg from horizontal. The holdup and pressure drop behaviors are strongly affected by oil-water flow patterns and inclination angle. Oil-water flows have been grouped into two major categories based on the status of the continuous phase, including water-dominated and oil-dominated flow patterns. Water-dominated flow patterns generally showed significant slippage, but relatively low frictional pressure gradients. In contrast, oil-dominated flow patterns showed negligible slippage, but significantly large frictional pressure gradients. A new mechanistic model is proposed to predict the water holdup in vertical wellbores based on a drift-flux approach. The drift flux model was found to be adequate to calculate the holdup for high slippage flow patterns. New closure relationships for the two-phase friction factor for oil-dominated and water-dominated flow patterns are also proposed.

Investigation of a Two-Phase Siphon: Pressure Drop Characteristics, Flow Prediction, and Flow Regime Change Prediction

Volume 3 ◽  
2004 ◽  
Author(s):  
J. Howard Arthur ◽  
Charles D. Morgan ◽  
Cory D. Engelhard ◽  
Berton Austin
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Distribution Parameter ◽  
Regime Transition ◽  
Two Phase ◽  
Flow Rates ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Regime Transition ◽  
Flux Model

In some nuclear power plants, a passive siphon breaking system is used to prevent the spent fuel tank from draining in the event of a break in the vertical leg of the heat exchanger piping. A hole is drilled in the horizontal leg of the piping. When the water level in the tank drops below the pipe level air is sucked into the system. When sufficient air is entrained in the pipe the siphon will break. A model to predict the flow rate in a vertical siphon was developed in reference 1 using the homogeneous flow model. The predicted flow rates were greater than measured flow rates. In order to improve the predictive capability, pressure drop measurements were obtained from ten foot vertical test sections with nominal diameters of 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 inches. Values of the distribution parameter, Co, for the drift flux model were determined from the pressure drop data. When the model of reference 1 is changed from homogeneous flow to drift flux model with the distribution parameter determined from the pressure drop data, good agreement with measured liquid flow rates is obtained. The improved model, along with the correlation for the siphon break condition obtained provides a good method for determining the hole size required to break the siphon. There is a paucity of data for two-phase flow regime transition where the flow is in the downward direction that is typical in a siphon. Flow regime transition data were obtained using the test sections listed above. The flow map of Oshinowo2 et al. gave a reasonable prediction of the transition from bubbly to slug flow. None of the references investigated gave an adequate prediction of the point where the siphon would break. A correlation for the siphon break point was developed.

Use of a Transient Model for Studying Kick Migration Velocities and Build-Up Pressures in a Closed Well

2021 ◽  
Author(s):  
Thea Hang Ngoc Tat ◽  
Dalila Gomes ◽  
Kjell Kåre Fjelde
Keyword(s):  
Flow Model ◽  
Transient Flow ◽  
Flow Patterns ◽  
Drilling Fluids ◽  
Transient Model ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Gas Kick ◽  
Flux Model ◽  
Migration Velocities

Abstract The objective of the paper is to show that using pressure build-up curves for estimating kick migration velocities can be unreliable. This will be demonstrated by using a transient flow model where different flow patterns including suspended gas are considered. Suspended gas will occur in Non-Newtonian drilling fluids. This can also be the reason why there is reported large discrepancies in literature about what the gas kick migration velocities can be. A transient flow model based on the drift flux model supplemented with a gas slip relation will be used. The model will be solved by an explicit numerical scheme where numerical diffusion has been reduced. Different flow patterns are included i.e. suspended gas, bubble flow, slug flow and transition to one-phase gas. Kick migration in a closed well will be studied to study how pressure build-ups evolve. A sensitivity analysis will be performed varying kick sizes, suspension limits and changing the transition intervals between the flow patterns. It is seen in literature that the slope of the pressure build-up for a migrating kick in a closed well has been used for estimating what the kick velocity is. It has been reported earlier that this can be an unreliable approach. In the simulation study, it is clearly demonstrated that the suspension effect will have a significant impact of reducing the slopes of the pressure build-ups from the start of the kick onset. In some severe cases, the pressure builds up but then it reaches a stable pressure quite early. In these cases, the kick has stopped migrating in the well. However, in the cases where the kicks are still migrating, it seems that the bulk of the kick moves at the same velocity even though the degree of suspension is varied and gives different slopes for the pressure build-up. Hence, it seems impossible to deduce a unique gas velocity from different pressure build-up slopes. However, abrupt changes in the slope of the pressure build-up indicate flow pattern transitions.

Prediction of pressure drop in Venturi based on drift-flux model and boundary layer theory

2020 ◽  
Vol 71 ◽  
pp. 101673 ◽  
Author(s):  
Haitao Wu ◽  
Ying Xu ◽  
Xinqiang Xiong ◽  
Ekber Mamat ◽  
Jinghan Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Pressure Drop ◽  
Boundary Layer Theory ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flux Model

Interfacial Structures and Regime Transition in Co-Current Downward Bubbly Flow

2004 ◽  
Vol 126 (4) ◽  
pp. 528-538 ◽  
Author(s):  
S. Kim ◽  
S. S. Paranjape ◽  
M. Ishii ◽  
J. Kelly
Keyword(s):  
Two Phase Flow ◽  
Bubbly Flow ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Parameters ◽  
Interfacial Structures ◽  
Flux Model

The vertical co-current downward air-water two-phase flow was studied under adiabatic condition in round tube test sections of 25.4-mm and 50.8-mm ID. In flow regime identification, a new approach was employed to minimize the subjective judgment. It was found that the flow regimes in the co-current downward flow strongly depend on the channel size. In addition, various local two-phase flow parameters were acquired by the multi-sensor miniaturized conductivity probe in bubbly flow. Furthermore, the area-averaged data acquired by the impedance void meter were analyzed using the drift flux model. Three different distributions parameters were developed for different ranges of non-dimensional superficial velocity, defined by the ration of total superficial velocity to the drift velocity.

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