Evaluation of velocity fields in horizontal gas-liquid intermittent flows using Stereoscopic-PIV and instantaneous masking procedure

The main goal of this work was to obtain well-converged liquid velocity profiles for intermittent gas-liquid flows in a horizontal pipe. To this end, air and water with superficial velocities of JG = 0.5 m/s and JL = 0.3, 0.4 and 0.5 m/s, respectively, were driven into a 18-m acrylic test section with an inner diameter of 40 mm. All three-components of the velocity vectors were measured in a pipe cross-section using a highfrequency stereoscopic PIV system, together with the laser induced fluorescence technique. Photogates were used to measure the unit cell translational velocity, as well as to trigger data acquisition, allowing the calculation of ensemble-averaged velocity fields at specific positions, referenced to the gas-bubble nose tip position. An instantaneous image masking procedure was implemented, allowing the determination of non-dimensional ensemble-averaged velocity profile in the liquid film, referenced to gas-bubble boundary. The high-frequency system employed allowed the determination of the influence of the faster-moving gas bubble on the liquid velocity field in the plug region. The data presented are relevant to the validation and improvement of one-dimensional two-phase numerical models, as well as to better understand this complex flow.

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Liquid and Gas Phase Velocity Measurements for Two Phase Flow in a Branching Microchannel Network

Volume 11: Micro and Nano Systems, Parts A and B ◽

10.1115/imece2007-41621 ◽

2007 ◽

Cited By ~ 1

Author(s):

Younghoon Kwak ◽

Deborah Pence ◽

James Liburdy ◽

Vinod Narayanan

Keyword(s):

Liquid Velocity ◽

Leading Edge ◽

Velocity Measurements ◽

Trailing Edge ◽

Two Phase ◽

Order Of Magnitude ◽

Image Pairs ◽

Superficial Gas Velocity ◽

Liquid Flows ◽

Velocity Deficits

This is a work in progress. The objective of the present work is to develop techniques for assessing velocity deficits in branching microchannel networks. Liquid velocity distributions were acquired using μPIV in gas-liquid flows through the initial branch in a fractal-like branching microchannel flow network. Gas interface velocities were determined along the centerline of the channel. The flow rate of air and water were 0.0016 g/min and 20 g/min, respectively. The primary observed flow regime was elongated bubbles. Experimental liquid velocities well matched the 0.20 m/s superficial liquid velocity. Experimental interface velocities were approximately an order of magnitude higher than the superficial gas velocity of 0.01 m/s. Velocity deficits based on measurements are on the order of 0.065 m/s. Using interfacial velocities at the channel centerline, the trailing edge velocity was observed to be 15% percent faster, on average, than the leading edge velocity. This could be attributed to bubbles expanding into the bifurcation. Twenty percent standard deviations in average interface velocities were attributed to insufficient samples as well as projected to be a consequence of changing shape of the interface between consecutive image pairs. Changes in bubble shape may also be responsible for the observed differences between leading and trailing edge velocities.

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Non-Invasive Method for Velocity and Slug Length Measurements in Gas/Liquid Flow in Horizontal Pipes

Fluids Engineering ◽

10.1115/imece2005-82885 ◽

2005 ◽

Cited By ~ 1

Author(s):

S. Al-Lababidi ◽

M. L. Sanderson

Keyword(s):

Liquid Flow ◽

Liquid Velocity ◽

Correlation Technique ◽

Translational Velocity ◽

Two Phase ◽

Horizontal Pipe ◽

Horizontal Pipes ◽

Non Invasive ◽

Gas Liquid Flow ◽

Superficial Gas Velocity

A method was developed for the measurement of slug frequency, slug velocity and slug length of two-phase gas/liquid flow under slug conditions in 2-inch horizontal pipe. The method consists of two pairs of ultrasonic transducers with 1MHz frequency. Non-invasive detection for slugs was achieved over a range of (0.1–1 ms−1) superficial liquid velocity and (0.1–3 ms−1) superficial gas velocity. The slug translational velocity was measured using a cross correlation technique for the modulated ultrasonic signals received. The slug length was measured after measuring the slug time t(slug) and slug translational velocity. The slug parameters measured were extensively compared with conductivity probes measurements and experimental correlations.

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Computational Fluid Dynamics Simulations of Gas-liquid Two-phase Flow Characteristics through a Vertical to Horizontal Right Angled Elbow

ASEAN Journal on Science and Technology for Development ◽

10.29037/ajstd.344 ◽

2017 ◽

Vol 30 (1&2) ◽

pp. 1-16 ◽

Cited By ~ 5

Author(s):

N. Z. Aung ◽

T. Yuwono

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Gas Phase ◽

Test Section ◽

Two Phase Flow ◽

Liquid Velocity ◽

Phase Flow ◽

Cfd Simulations ◽

Two Phase ◽

Horizontal Pipe

Having a clear understanding on the phase distribution of gas-liquid two-phase flow through elbow bends is vital in mixing and separation system designs. This paper presents the computational fluid dynamics (CFD) simulations and experimental observations of gas-liquid two-phase flow pattern characteristic through a vertical to horizontal right angled (90°) elbow. Experimental observations were conducted in a transparent test section that consisted of a vertical pipe, elbow bend and horizontal pipe with an inside diameter of 0.036 m. The CFD simulations were performed by using a computer software package, FLUENT 6.2. Bubbly flow conditions were created in the vertical test section with the variation of superficial liquid Reynolds number from 13 497 to 49 488 and volumetric gas quality from 0.05 to 0.2. The CFD results showed a good agreement with experimental results in the following observations. The results showed that gas-liquid flow pattern inside and downstream of the elbow bend mainly depended on liquid velocity and it is also influenced by gas quality at high liquid velocities. At lower liquid velocities, gas-liquid separation began early in the elbow bend and gas-phase migrated to outer bend. Then, it smoothly transformed to stratified flow at elbow outlet. When the liquid velocity was further increased, the liquid phase occupied the outer bend rubbing the gas phase to the inner bend and delayed the formation of gas layer in the horizontal pipe. The increase of gas quality in higher liquid velocities promoted gas core formation at the elbow exit and caused wavy gas layers at the downstream of the elbow.

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Determination of a Bubble Drag Coefficient during the Formation of Single Gas Bubble in Upward Coflowing Liquid

Processes ◽

10.3390/pr8080999 ◽

2020 ◽

Vol 8 (8) ◽

pp. 999

Author(s):

Przemysław Luty ◽

Mateusz Prończuk

Keyword(s):

Drag Coefficient ◽

Chemical Engineering ◽

Liquid Velocity ◽

Bubble Diameter ◽

Bubble Formation ◽

Hydraulic Drag ◽

Gas Bubble ◽

Flowing Liquid ◽

Engineering Research

Bubble flow is present in many processes that are the subject of chemical engineering research. Many correlations for determination of the equivalent bubble diameter can be found in the scientific literature. However, there are only few describing the formation of gas bubbles in flowing liquid. Such a phenomenon occurs for instance in airlift apparatuses. Liquid flowing around the gas bubble creates a hydraulic drag force that leads to reduction of the formed bubble diameter. Usually the value of the hydraulic drag coefficient, cD, for bubble formation in the flowing liquid is assumed to be equal to the drag coefficient for bubbles rising in the stagnant liquid, which is far from the reality. Therefore, in this study, to determine the value of the drag coefficient of bubbles forming in flowing liquid, the diameter of the bubbles formed at different liquid velocity was measured using the shadowgraphy method. Using the balance of forces affecting the bubble formed in the coflowing liquid, the hydraulic drag coefficient was determined. The obtained values of the drag coefficient differed significantly from those calculated using the correlation for gas bubble rising in stagnant liquid. The proposed correlation allowed the determination of the diameter of the gas bubble with satisfactory accuracy.

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Effect of Drag Reducing Polymers on Two-Phase Gas–Liquid Flows in a Horizontal Pipe

Chemical Engineering Research and Design ◽

10.1205/cerd.82.12.1583.58033 ◽

2004 ◽

Vol 82 (12) ◽

pp. 1583-1588 ◽

Cited By ~ 33

Author(s):

A. Al-sarkhi ◽

A. Soleimani

Keyword(s):

Two Phase ◽

Horizontal Pipe ◽

Liquid Flows

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A suitability analysis of transient one-dimensional two-fluid numerical models for simulating two-phase gas-liquid flows based on benchmark problems

Computers & Fluids ◽

10.1016/j.compfluid.2021.105070 ◽

2021 ◽

pp. 105070

Author(s):

Carina Nogueira Sondermann ◽

Raphael Viggiano Neves de Freitas ◽

Felipe Bastos de Freitas Rachid ◽

Gustavo C.R. Bodstein

Keyword(s):

Numerical Models ◽

Benchmark Problems ◽

Suitability Analysis ◽

Two Phase ◽

One Dimensional ◽

Liquid Flows ◽

Two Fluid

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A Modified Model for Predicting Flow Regime Transitions in Horizontal Gas-Liquid Flow

10.1115/imece1999-1233 ◽

1999 ◽

Author(s):

N. H. Mostafa ◽

E. S. El Mitwally ◽

A. A. El Desoky

Keyword(s):

Shear Stress ◽

Flow Regime ◽

Two Phase Flow ◽

Liquid Velocity ◽

Interfacial Shear Stress ◽

Phase Flow ◽

Two Phase ◽

Horizontal Pipe ◽

Gas Liquid Flow ◽

Different Diameters

Abstract A Theoretical model for identifying the flow regime transition of air-water two-phase flow in a horizontal pipe is presented. In this work, when mapping the two-phase flow, the nonuniform liquid-to-wall shear stress around the pipe circumference and the interfacial shear stress were taken into consideration. This model was found in agreement with the experimental map of Mandhane et al. (1974) and the Modified Baker map (Ball et al. 1970) for mapping the two-phase flow. The proposed model is plotted for different pipe diameters. The superficial liquid velocity was found to increase four times in the stratified and bubble flow regimes when the pipe diameter was increased from 2.5 to 5 cm. This model enables for any user for working in different diameters.

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Study of Available Turbulence and Cavitation Models to Reproduce Flow Patterns in Confined Flows

Journal of Fluids Engineering ◽

10.1115/1.4033372 ◽

2016 ◽

Vol 138 (9) ◽

Cited By ~ 3

Author(s):

M. Coussirat ◽

F. Moll ◽

F. Cappa ◽

A. Fontanals

Keyword(s):

Numerical Models ◽

Internal Flow ◽

Numerical Results ◽

Flow State ◽

Quantitative Criterion ◽

Complex Flow ◽

Two Phase ◽

Computational Costs ◽

Extensive Analysis ◽

Confined Flows

Cavitating flow in nozzles is a complex flow which implies a highly turbulent two-phase one. An accurate simulation which improves some numerical results found in the literature was achieved by means of an extensive analysis of the capabilities of several numerical models for turbulence and cavitation. The analysis performed involves calibration/optimization tasks based on the physics of this kind of flow. This work aims to provide a quantitative criterion for the judgment of internal flow state, because it was demonstrated that the numerical results obtained with noncalibrated models could be enhanced by means of a careful calibration and thus saving computational costs.

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