Inception and termination of the core-annular flow pattern for oil-water downflow through a vertical pipe

AIChE Journal ◽  
2011 ◽  
Vol 58 (7) ◽  
pp. 2020-2029 ◽  
Author(s):  
Sumana Ghosh ◽  
Gargi Das ◽  
Prasanta Kumar Das
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Vertical Pipe ◽  
The Core ◽  
Oil Water

Direct numerical simulation of a turbulent core-annular flow with water-lubricated high viscosity oil in a vertical pipe

2018 ◽  
Vol 849 ◽  
pp. 419-447 ◽  
Author(s):  
Kiyoung Kim ◽  
Haecheon Choi
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Pipe Flow ◽  
Annular Flow ◽  
Volume Fraction ◽  
Phase Interface ◽  
High Viscosity ◽  
Vertical Pipe ◽  
The Core ◽  
High Viscosity Oil

The characteristics of a turbulent core-annular flow with water-lubricated high viscosity oil in a vertical pipe are investigated using direct numerical simulation, in conjunction with a level-set method to track the phase interface between oil and water. At a given mean wall friction ($Re_{\unicode[STIX]{x1D70F}}=u_{\unicode[STIX]{x1D70F}}R/\unicode[STIX]{x1D708}_{w}=720$, where $u_{\unicode[STIX]{x1D70F}}$ is the friction velocity, $R$ is the pipe radius and $\unicode[STIX]{x1D708}_{w}$ is the kinematic viscosity of water), the total volume flow rate of a core-annular flow is similar to that of a turbulent single-phase pipe flow of water, indicating that water lubrication is an effective tool to transport high viscosity oil in a pipe. The high viscosity oil flow in the core region is almost a plug flow due to its high viscosity, and the water flow in the annular region is turbulent except for the case of large oil volume fraction (e.g. 0.91 in the present study). With decreasing oil volume fraction, the mean velocity profile in the annulus becomes more like that of turbulent pipe flow, but the streamwise evolution of vortical structures is obstructed by the phase interface wave. In a reference frame moving with the core velocity, water is observed to be trapped inside the wave valley in the annulus, and only a small amount of water runs through the wave crest. The phase interface of the core-annular flow consists of different streamwise and azimuthal wavenumber components for different oil holdups. The azimuthal wavenumber spectra of the phase interface amplitude have largest power at the smallest wavenumber whose corresponding wavelength is the pipe circumference, while the streamwise wavenumber having the largest power decreases with decreasing oil volume fraction. The overall convection velocity of the phase interface is slightly lower than the core velocity. Finally, we suggest a predictive oil holdup model by defining the displacement thickness in the annulus and considering the boundary layer characteristics of water flow. This model predicts the variation of the oil holdup with the superficial velocity ratio very well.

Flow Patterns in Heavy Crude Oil-Water Flow

2001 ◽  
Author(s):  
Antonio C. Bannwart ◽  
Oscar M. H. Rodriguez ◽  
Carlos H. M. de Carvalho ◽  
Isabela S. Wang ◽  
Rosa M. O. Vara
Keyword(s):  
Crude Oil ◽  
Flow Pattern ◽  
Heavy Oil ◽  
Annular Flow ◽  
Effective Means ◽  
Practical Importance ◽  
Flow Patterns ◽  
Heavy Crude Oil ◽  
Oil Water ◽  
Heavy Crude

Abstract This paper is aimed to an experimental study on the flow patterns formed by heavy crude oil (488 mPa.s, 925.5 kg/m3 at 20 °C) and water inside vertical and horizontal 1 in. pipes. The interfacial tension was 29 dynes/cm. Effort is concentrated into flow pattern characterization, which was visually defined. The similarities with gas-liquid flow patterns are explored and the results are expressed in flow maps of the superficial velocities. In contrast with other studies, the annular flow pattern (‘core annular flow’) was observed in both horizontal and vertical test sections. In fact this flow pattern typically occurs in heavy oil-water flows at low water input fractions. Because of the practical importance of core flow in providing an effective means for heavy oil production and transportation, this paper discusses two criteria that favor its occurrence in pipes.

Flow Patterns in Heavy Crude Oil-Water Flow

2004 ◽  
Vol 126 (3) ◽  
pp. 184-189 ◽  
Author(s):  
Antonio C. Bannwart ◽  
Oscar M. H. Rodriguez ◽  
Carlos H. M. de Carvalho ◽  
Isabela S. Wang ◽  
Rosa M. O. Vara
Keyword(s):  
Crude Oil ◽  
Flow Pattern ◽  
Heavy Oil ◽  
Annular Flow ◽  
Effective Means ◽  
Practical Importance ◽  
Flow Patterns ◽  
Heavy Crude Oil ◽  
Oil Water ◽  
Heavy Crude

This paper is aimed to an experimental study on the flow patterns formed by heavy crude oil (initial viscosity and density 488 mPa s, 925.5kg/m3 at 20°C) and water inside vertical and horizontal 2.84-cm-i.d. pipes. The oil-water interfacial tension was 29 dyn/cm. Effort is concentrated into flow pattern characterization, which was visually defined. The similarities with gas-liquid flow patterns are explored and the results are expressed in flow maps. In contrast with other studies, the annular flow pattern (“core annular flow”) was observed in both horizontal and vertical test sections. These flow pattern tends to occur in heavy oil-water flows at low water input fractions. Because of the practical importance of core flow in providing an effective means for heavy oil production and transportation, this paper discusses criteria that favor its occurrence in pipes.

Experimental study of viscosity effects on heavy crude oil-water core-annular flow pattern

2018 ◽  
Vol 92 ◽  
pp. 270-285 ◽  
Author(s):  
Caio A.M. Cavicchio ◽  
Jorge L. Biazussi ◽  
Marcelo S. de Castro ◽  
Antonio C. Bannwart ◽  
Oscar M.H. Rodriguez ◽  
...  
Keyword(s):  
Experimental Study ◽  
Crude Oil ◽  
Flow Pattern ◽  
Annular Flow ◽  
Heavy Crude Oil ◽  
Viscosity Effects ◽  
Oil Water ◽  
Heavy Crude

Characteristics of the Interfacial Wave Velocity on the Liquid Film of Annular Flow for Gas-Oil-Water Three-Phase Flow in a Horizontal Pipe

2011 ◽  
Vol 402 ◽  
pp. 816-819
Author(s):  
Hai Qin Wang ◽  
Yong Wang ◽  
Lei Zhang ◽  
Jin Hai Gong ◽  
Zhen Yu Wang
Keyword(s):  
Flow Pattern ◽  
Wave Velocity ◽  
Annular Flow ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Gas Oil ◽  
Interfacial Wave ◽  
Three Phase ◽  
Three Phase Flow ◽  
Oil Water

The experiments were conducted in a horizontal multiphase flow test loop (50mm inner diameter, 40m long) and the cross-correlation technology was used for the study of the characteristics of the interfacial wave velocity about two types of annular flow regimes (AN║DO/W and AN║DW/O) for gas-oil-water three-phase flow. The results show that the interfacial wave velocity on the liquid film of AN║DO/W flow pattern and AN║DW/O flow pattern all increases with the increase of gas superficial velocity and liquid superficial velocity on the condition of fixed ratio of oil and water flow rates, but the difference is that the increase is a linear monotonic increase for AN║DO/W flow pattern and a non-linear increase for AN║DW/O flow pattern, and the liquid superficial velocity makes a larger contribution than the gas superficial velocity. The interfacial wave velocity also increases with the increase of input water cut in liquid at different gas superficial velocities under the conditions of liquid superficial velocity fixed.

Bubble Analogy and Stabilization of Core-Annular Flow

2000 ◽  
Vol 123 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Antonio C. Bannwart
Keyword(s):  
Cross Section ◽  
Annular Flow ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Interface Shape ◽  
Laboratory Measurements ◽  
Horizontal Pipe ◽  
The Core ◽  
Oil Water ◽  
Momentum Conservation Equation

A theory for the stabilization of annular liquid-liquid flow (i.e., core-annular flow) in a horizontal pipe is proposed. Based upon the analysis of the momentum conservation equation in the cross section of the flow, including the effects of peripheral flow in the annulus and interfacial tension, an equation is obtained which describes the interface shape. Results for the height-to-width aspect ratio of the core are compared with laboratory measurements done by the author for a heavy oil-water core-annular flow. A criterion for stabilization of this interesting flow pattern is proposed.

Flow-induced vibration and noise in control valve

2015 ◽  
Vol 229 (18) ◽  
pp. 3368-3377 ◽  
Author(s):  
Li-fei Zeng ◽  
Guan-wei Liu ◽  
Jing-ru Mao ◽  
Shun-sen Wang ◽  
Qi Yuan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Annular Flow ◽  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Control Valve ◽  
Steam Turbines ◽  
Core Flow ◽  
Control Valves ◽  
The Core

Control valves are used as flow regulators for steam turbines, which operate under wide ranges of valve openings and pressure ratios. The inherent throttling action and complex 3D flow in control valves result in vibration and intolerable noise at small and medium valve openings. The vibration and noise clearly are firmly with the flow pattern. Experiments and numerical simulation are the primary means of determining the mechanisms. In this paper, a phenomenon of sound mutation in control valve was experimentally observed by continuously changing the pressure ratio. This phenomenon is explained for the first time. Different noise and pressure fluctuations can appear even under the same condition, depending on the process of changing the pressure ratio. A method of continuously changing the pressure ratio was used in the unsteady numerical simulation to reveal the mechanism. The results show that sound mutation occurs due to the change of annular flow and core flow. The annular flow has a lower noise and a more stable flow pattern than the core flow. Sound mutation can be used as a simple way of determining the ranges of the core flow and the annular flow.

scholarly journals Flow Pattern Map of Flow Boiling in a Rectangular Channel Filled with Porous Media

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2440
Author(s):  
Youngwoo Kim ◽  
Dae Yeon Kim ◽  
Kyung Chun Kim
Keyword(s):  
Porous Media ◽  
Flow Pattern ◽  
Flow Regime ◽  
Annular Flow ◽  
Flow Boiling ◽  
Rectangular Channel ◽  
Flow Patterns ◽  
Flow Pattern Map ◽  
Mist Flow ◽  
Churn Flow

A flow visualization study was carried out for flow boiling in a rectangular channel filled with and without metallic random porous media. Four main flow patterns are observed as intermittent slug-churn flow, churn-annular flow, annular-mist flow, and mist flow regimes. These flow patterns are clearly classified based on the high-speed images of the channel flow. The results of the flow pattern map according to the mass flow rate were presented using saturation temperatures and the materials of porous media as variables. As the saturation temperatures increased, the annular-mist flow regime occupied a larger area than the lower saturation temperatures condition. Therefore, the churn flow regime is narrower, and the slug flow more quickly turns to annular flow with the increasing vapor quality. The pattern map is not significantly affected by the materials of porous media.

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