Effect of diameter and axial location on upward gas–liquid two-phase flow patterns in intermediate-scale vertical tubes

In this study, air-water two-phase flow patterns in a two-dimensional vertical helical channel are investigated. The simulations are performed using Open-FOAM software. The single-fluid method and Eulerian−Eulerian approach are used to solve the governing equations. The paper focuses on different flow patterns based on the change in the apparent velocity of water and air, and the influence of volume fraction of the air at the entrance of the channel. The variations of turbulent kinetic energy, volume fraction and velocity profile are presented. The range of air and water apparent velocities at the channel entrance is 0.05-10 m s −1 and 0.1-1.5 m s −1 , respectively. According to the results, four flow patterns including bubbly, churn, turbulent, and annular are observed. It is demonstrated that for the bubbly regime, the values of volume fraction of phases are close to unity. When the air inlet velocity is very high, the two-phase flow forms the annular flow pattern. Keywords: air-water two-phase flow, volume of fluid method, Eulerian −Eulerian method, flow patterns, helical channel

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“…compares the flow patterns obtained from the present simulations and those reported byAnsari and Azadi (Ansari and Azadi 2016).…”

supporting

confidence: 56%

“…In order to verify the present simulations, the flow patterns are compared with those reported by experimental results of Ansari and Azadi (Ansari and Azadi 2016). They considered the two-phase flow of air and water in a vertical cylindrical tube with a diameter of 70 mm.…”

Section: Validationmentioning

confidence: 89%

Numerical study of air-water two-phase flow in a two-dimensional vertical helical channel

2019

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Understanding two‐phase flow behaviour: CFD Assessment of silicone oil–air and water–air in an intermediate vertical pipe

Mondal,

Lahiri,

Ghanta

2024

Can J Chem Eng

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The study utilized computational fluid dynamics (CFD) simulations employing the volume of fluid (VOF) model to analyze silicone oil–air flows in a vertical pipe with a diameter of 67 mm. Various structured meshes ensured grid independence, and the k‐ε realizable model addressed turbulence. The analysis characterized bubbly to annular flows, involving the evaluation of flow patterns, radial void fractions, void fraction time series, probability density functions (PDFs), power spectral densities (PSDs), and mean void fractions. Results indicated a transition from bubbly to annular flow with increasing gas velocities and notable changes in radial void fraction profiles. Void fraction exhibited significant variations with distinct flow patterns at constant liquid velocity. PDFs identified flow regimes, and PSDs revealed frequency patterns. CFD results were validated against experiments, demonstrating good agreement. The validated CFD model was utilized to investigate radial gas velocities and pressure drops, revealing a shift from uniform velocity distributions to irregular patterns and a decrease in total pressure drop with an increase in gas superficial velocity. The model was also applied to a water‐air system to explore two‐phase flow behaviour. The impact of superficial gas velocity on flow patterns and radial void fractions was studied through numerical analysis and compared with the silicone oil‐air system. Results showed that at extreme gas velocities (0.06 and 5.53 m/s), silicone oil exhibited bubbly and annular flows, while water displayed cap bubbly and churn flows. The significant variation in radial void fraction at these velocities emphasized the impact of fluid properties.

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Numerical simulation of the evaporator in two–phase thermosyphon loop for passive containment cooling system

Yin

Zhou

et al. 2023

Annals of Nuclear Energy

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Effect of diameter and axial location on upward gas–liquid two-phase flow patterns in intermediate-scale vertical tubes

Cited by 11 publications

References 24 publications

Numerical study of air-water two-phase flow in a two-dimensional vertical helical channel

Numerical study of air-water two-phase flow in a two-dimensional vertical helical channel

Understanding two‐phase flow behaviour: CFD Assessment of silicone oil–air and water–air in an intermediate vertical pipe

Numerical simulation of the evaporator in two–phase thermosyphon loop for passive containment cooling system

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