Characteristics of Air-Oil Slug Flow in Inclined Pipe Using Tomographic Techniques

2011 ◽  
Author(s):  
Lokman A. AbdulKareem ◽  
V. Hernandez-Perez ◽  
S. Sharaf ◽  
Barry J. Azzopardi
Keyword(s):  
Slug Flow ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Wire Mesh ◽  
Internal Diameter ◽  
Cross Sectional ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Pipe Inclination

The structure of gas liquid flow in horizontal and vertical pipes to some extent is well understood. However, the situation in inclined pipes is much more difficult with very little work published in literature. Changes in physical phenomena occur as the pipe inclination angle varies from the vertical through to inclined and then to horizontal. This work describes a study carried out at the University Of Nottingham on the effects of inclination on gas / liquid slug flow. Two advanced tomography techniques were applied simultaneously to the flow of a mixture of air and silicone oil in a 67 mm internal diameter pipe and the pipe was inclined at angles 0, 5, 10, 30, 45, 60, 80, 90 degrees. This paper reports on the use of twin plane electrical capacitance tomography (ECT) system developed by TomoFlow electronics Ltd to measure flow characteristics in gas-liquid flows. We report measurements over a range of liquid superficial velocities from 0.05 m/s to 0.5 m/s and gas superficial velocities from 0.06 m/s to 6 m/s at all the above angles in a pipe 6 m long. A second technique, Capacitance Wire Mesh Sensor (WMS) developed at Forschungszentrum Rossendorf-Dresden/Germany was also present in the tests, The results for the two sensors are shown to be within 1% of each other in some instances when comparing cross-sectional averaged void fraction. The data was recorded at an acquisition frequency of 1000 Hz over an interval of 60 seconds. This enabled an examination of the flow to be carried out at several levels of complexity. Both measuring sensors provide time and cross-sectionally resolved information about the spatial distribution of the phases. In present paper, the effect of inclination on the characteristics of slug flow is presented. Radial gas volume fraction profiles and bubble size distributions were also processed from the wire-mesh sensor output. The results indicate that the pipe inclination has a significant effect on the slug flow characteristics.

Effect of Inclination on Slug Flow Characteristics

2010 ◽  
Author(s):  
Lokman A. AbdulKareem ◽  
S. Sharaf ◽  
Barry J. Azzopardi ◽  
Andrew Hunt
Keyword(s):  
Slug Flow ◽  
Volume Fraction ◽  
Phase Distribution ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Wire Mesh ◽  
Sensor Data ◽  
Internal Diameter ◽  
Liquid Slug ◽  
Taylor Bubble

Modern oil/gas well drilling methods in particular in the offshore industry involve deviated drilling in which the production tubing can be inclined at any angle between the vertical and the horizontal. Riser tubes from the seabed to the surface or to floating production vessels (FPSO) will also rarely be exactly vertical. This work describes a study carried out at the University Of Nottingham on the effects of inclination on gas / liquid slug flow. Two advanced tomography techniques were applied simultaneously to the flow of a mixture of air and silicone oil in a 67 mm internal diameter pipe and the pipe was inclined at various angles. A twin plane Electrical Capacitance Tomography (ECT) electrode system driven by Tomoflow electronics was positioned below a Capacitance Wire Mesh Sensor (WMS) developed at Forschungszentrum Rossendorf-Dresden/Germany M. J. Da Silva et al [2]. This enabled an examination of the flow to be carried out at several levels of complexity. Both measuring sensors provide time and cross-sectionally resolved information about the spatial distribution of the phases. Conditions studied were superficial velocities for air ranged from 0.05 to 5.5 m/s and for silicone oil ranged from 0.0 m/s to 0.5 m/s. In present paper, the effect of inclination on the phase distribution in two phase gas liquid slug flow is presented. The liquid hold up within the slug region and in the elongated bubble zone and the averaged liquid hold up were calculated from the output data of the two measurements techniques. Radial gas volume fraction profiles and bubble size distributions were also processed from the wire-mesh sensor data. The shapes of the large bubbles and waves were compared for different inclination angles. The results indicate that the pipe inclination has a significant effect on the slug flow characteristics. Both Taylor bubble and small bubbles in the slug region tend to flow along the upper pipe wall and causing significant variation of Taylor bubble rise velocity with inclination angle.

Interrogation of Gas/Oil Flow in a Vertical Using Two Tomographic Techniques

2009 ◽  
Author(s):  
Lokman A. AbdulKareem ◽  
Barry J. Azzopardi ◽  
Sebastian Thiele ◽  
Andrew Hunt ◽  
Marco J. Da Silva
Keyword(s):  
Void Fraction ◽  
Silicone Oil ◽  
Wire Mesh ◽  
Internal Diameter ◽  
Cross Sectional ◽  
Void Fractions ◽  
Radial Profiles ◽  
Oil Flow ◽  
Bubble Sizes ◽  
Capacitance Tomography

Two tomographic techniques have been applied to the flow in a 67 mm internal diameter vertical pipe. One is Electrical Capacitance Tomography (ECT) mounted on the outside of the non-conducting pipe wall. Another technique, known as the Wire Mesh Sensor (WMS) was used. The measuring systems provide time and cross-sectionally resolved information about the spatial distribution of the phases. The information can be used to obtain space and time averaged void fractions, radial profiles of time averaged void fraction and cross-sectional averaged time series of void fraction. Simultaneous measurements were made with the two techniques for gas superficial velocities of 0.05–5.5 m/s and liquid superficial velocities of 0–0.7 m/s with air and silicone oil as the fluids. Bubble, slug and churn flows were identified from the characteristic signatures of the Probability Density Functions of the cross-sectionally averaged void fraction. In addition, the detailed shape of individual large bubbles has been extracted. The output of both instruments shows clearly that the shapes of the large bubbles in slug flow are distinctly different from the smooth bullet-shaped. In this larger diameter pipe, the interface is much more disturbed. In addition, flow can be classified according to the sizes of bubbles present. Distributions of bubble sizes are presented and the fractions of gas flowing in different bubble sizes classes quantified.

Influence of Inclination Angle on Intermittent Two Phase Flows

2016 ◽  
Author(s):  
Josep Escrig Escrig ◽  
Buddhika Hewakandamby ◽  
Georgios Dimitrakis ◽  
Barry Azzopardi
Keyword(s):  
Time Series ◽  
Void Fraction ◽  
Time Series Data ◽  
Silicone Oil ◽  
Wire Mesh ◽  
Series Data ◽  
Intermittent Flow ◽  
Two Phase ◽  
Cross Sectional ◽  
Inclined Pipes

Intermittent gas and liquid two-phase flow was generated in a 6 m × 67 mm diameter pipe mounted rotatable frame (vertical up to −20°). Air and a 5 mPa s silicone oil at atmospheric pressure were studied. Gas superficial velocities between 0.17 and 2.9 m/s and liquid superficial velocities between 0.023 and 0.47 m/s were employed. These runs were repeated at 7 angles making a total of 420 runs. Cross sectional void fraction time series were measured over 60 seconds for each run using a Wire Mesh Sensor and a twin plane Electrical Capacitance Tomography. The void fraction time series data were analysed in order to extract average void fraction, structure velocities and structure frequencies. Results are presented to illustrate the effect of the angle as well as the phase superficial velocities affect the intermittent flows behaviour. Existing correlations suggested to predict average void fraction and gas structures velocity and frequency in slug flow have been compared with new experimental results for any intermittent flow including: slug, cap bubble and churn. Good agreements have been seen for the gas structure velocity and mean void fraction. On the other hand, no correlation was found to predict the gas structure frequency, especially in vertical and inclined pipes.

Two-Phase Upward Flow in a Slightly Deviated Pipe

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Abolore Abdulahi ◽  
Barry J. Azzopardi
Keyword(s):  
Void Fraction ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Visual Observation ◽  
Wire Mesh ◽  
Vertical Position ◽  
Upward Flow ◽  
Two Phase ◽  
Observation Methods

This study was undertaken to look at the effect of a slight inclination of pipe on upward flow characteristics especially at 10 deg from vertical position. Air-silicone oil flows in a 67 mm diameter pipe have been investigated using a capacitance wire mesh sensor (WMS) and electrical capacitance tomography (ECT). They provide time and cross-sectionally resolved data on void fraction. Superficial gas and liquid velocities of 0.05–1.9 and 0.05–0.5 were studied. Statistical methods and visual observation methods were used to characterize the fluid flows obtained into different flow patterns. From the output results from the tomography instruments, flow patterns were identified using both the reconstructed images as well as the characteristic signatures of Probability density function (PDF) plots of the time series of cross-sectionally averaged void fraction. Bubbly, cap bubble, slug, and churn flows were observed when the pipe was deviated by 10 deg from vertical pipe for the range of superficial gas velocities considered.

Experimental Characterization of Slug Flow on Solid Particle Transport in a 1 Deg Upward Inclined Pipeline

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers ◽  
Liang Wang
Keyword(s):  
Solid Particle ◽  
Solid Particles ◽  
Particle Suspension ◽  
Two Phase ◽  
Horizontal Orientation ◽  
Suspension Layer ◽  
Load Mode ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Pipe Inclination

This paper presents an experimental investigation on the influence of hydraulic and two phase (gas-liquid) flows on sand dune transportation resulting from a stationary flatbed, for horizontal and 1 deg upward pipe inclination. For gas-liquid conveying of solid particles, pipe inclination resulted in considerably different transport phenomena relative to those observed for horizontal orientation. Key distinguishing features such as backward bed movement and enhanced particle suspension were observed and were found to be highly gas-liquid ratio dependent. Using image processing, the solid particle suspension layer was quantified as a function of the gas-liquid flow. The measurements presented provide fundamental insights into the influence of upward pipe inclination on bed-load mode solid transportation in a closed conduit.

Experimental Investigation of Intermittent Gas-Liquid Flows on Solid Particle Transportation in Inclined Pipelines

2011 ◽  
Author(s):  
Liang Wang ◽  
Afshin Goharzadeh ◽  
Peter Rodgers
Keyword(s):  
Experimental Investigation ◽  
Solid Particle ◽  
Liquid Flow ◽  
Transport Phenomena ◽  
Solid Particles ◽  
Bed Load ◽  
Internal Diameter ◽  
Flow Phenomenon ◽  
Liquid Flows ◽  
Pipe Inclination

Solid particle transport in pipelines by fluids is widely encountered in energy industry processes, such as oil production, drilling of horizontal and inclined wells and mining. In contrast to the intensive research effort that has investigated solid transport in horizontal pipelines, limited studies have been published on solid transportation mechanism generated from an initial stationary particle bed in inclined pipes. Consequently the underlying mechanisms responsible for pipe inclination influence on bed-load transport phenomena have not been extensively assessed, particularly for gas-liquid conveying of solid particles. This paper presents an experimental investigation on the influence hydraulic and two phase (gas-liquid) flows on sand dune transportation resulting from a stationary flat bed as a function of (i) pipe inclination, (ii) gas liquid flow rate and (iii) initial sand bed thickness. Experiments were undertaken in a laboratory environment using a 14 m long transparent Plexiglas loop of 24 mm internal diameter to permit optical access. The three phases used were water, air and sand. High speed digital photography was employed to study the flow phenomenon and characteristics of sand bed transportation for the analysis variables (i) to (iii) under consideration. For hydraulic conveying of solid particles, it was found that 1° upward pipe inclination had negligible influence on both the flow phenomenon and solid-liquid flow pattern transition. In contrast, for gas-liquid conveying of solid particles, pipe inclination resulted in considerably different transport phenomena relative to that observed for the horizontal orientation. Differences such as backward bed movement and enhanced particle suspension were observed, and found to be highly gas-liquid ratio dependent. These measurements provide fundamental insights into the influence of upward pipe inclination on bed-load mode solid transportation in a closed conduit.

Visualization of Terrain-induced Slugging in W-shaped Pipeline

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Jungho Lee ◽  
Jaebum Park ◽  
Sangho Sohn
Keyword(s):  
Water Flow ◽  
Volume Fraction ◽  
Water Flow Rate ◽  
Slope Angle ◽  
Tidal Wave ◽  
Internal Diameter ◽  
Two Phase ◽  
Flow Phenomena ◽  
Gas Liquid Flow ◽  
Gas Volume

Gas-liquid two-phase flow in a circular pipeline is commonly encountered in an inclined pipeline of an offshore plant. To visualize gas-liquid flow phenomena in an inclined pipeline, the w-shaped transparent pipeline was fabricated with internal diameter of 2″ and slope angle of 25°. The terrain-induced slug flow in a steady-state was visualized at fixed water flow rate of 1 m3/hr and 80% GVF (Gas Volume Fraction). The air and water flow is initially maintained in stratified or wavy flow at t = 0 s. When the velocity difference between the air and water is high enough, the Kelvin-Helmholtz wave motion starts to occur just after at t = 0 s. As the wave reaches the top, the upward water flow is faced with the downward water flow in the main visualized region. When the airway is clogged, the air slug is formed at t = 0.02 s. When a huge tidal wave is observed at t = 0.1 s due to different velocity between the upward water and the downward water flow, the air slug travels at a greater velocity than the water flow. As the tidal wave enlarges its growth, the chaotic motion with scattered bubbles is exhibited at the gas-liquid interface. A series of the air slugging is periodically observed after near 0.5 s. At the second v-shaped pipeline, the slugging phenomena become even more severe due to an irregular water inflow from the first v-shaped pipeline.

Investigating the Effect of Pipe Inclination on Two-Phase Gas-Liquid Flows Using Advanced Instrumentation

2011 ◽  
Author(s):  
Abolore Abdulahi ◽  
Lokman A. Abdulkareem ◽  
Safa Sharaf ◽  
Mukhtar Abdulkadir ◽  
Valente Hernandez Perez ◽  
...  
Keyword(s):  
Time Series ◽  
Void Fraction ◽  
Flow Rate ◽  
Gas Flow ◽  
Oil And Gas ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Superficial Velocity ◽  
Wire Mesh ◽  
Two Phase

Pipes that make up oil and gas wells are not vertical but could be inclined at any angle between the vertical and the horizontal which is a significant technology of modern drilling. Hence, this study has been undertaken to look at the effect of inclination on flow characteristics especially at 10 degrees from both horizontal and vertical. Air/silicone oil flows in a 67 mm slightly deviated pipe have been investigated using advanced instrumentation: Wire Mesh Sensor Tomography (WMS) and Electrical Capacitance Tomography (ECT). They provide time and cross-sectionally resolved data on void fraction. Both the ECT probes and WMS were mounted on the inclined pipes upstream just at the point where flows were fully developed. By keeping the liquid flow rate constant at 10 litres/min (or liquid superficial velocity of 0.052m/s), gas flow rate was varied from 10 litres/min to 1000 litres/min (or gas superficial velocity from 0.05m/s to 4.7m/s). Then other values of liquid superficial velocity were considered. Visual observations were considered. Time series and void fraction were then measured for WMS while time series and liquid holdup were measured for ECT. The raw data were processed and then interpreted for proper analysis. From an analysis of the output from the tomography equipment, flow patterns were identified using both the reconstructed images as well as the characteristic signatures of Probability Density Function (PDF) plots of the time series of cross-sectionally averaged void fraction as suggested by some authors. Bubbly, slug and churn flows were observed for 10° from vertical pipe while bubbly, plug as well as slug flow when the pipe was inclined at 10° from horizontal. Examples of the PDFs are well illustrated which compares the use of ECT with WMS. In addition, statistical data such as Power Spectral Density (PSD), dominant frequency, mean void fraction as well as the structure velocities from cross correlation of the two planes of ECT have been identified.

Experimental Analysis of Gas–Liquid Flows in a Centrifugal Rotor

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Henrique Stel ◽  
Edgar M. Ofuchi ◽  
Rafael F. Alves ◽  
Sergio Chiva ◽  
Rigoberto E. M. Morales
Keyword(s):  
Liquid Flow ◽  
Experimental Analysis ◽  
Volume Fraction ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Phase Dynamics ◽  
Wide Range ◽  
Experimental Apparatus ◽  
Gas Liquid Flow ◽  
Liquid Flows

Abstract This work presents an experimental analysis of gas–liquid flows in a centrifugal rotor prototype. Pressure rise curves are evaluated considering a wide range of liquid and gas flowrates and different rotating speeds. An innovative apparatus including a dynamic sealing system, back illumination, and filming in a rotating frame of reference is employed to visualize gas–liquid flow patterns at different operating conditions. Volume fraction measurement and bubble-size evaluation are also taken into account. The experimental apparatus allowed analyzing details of the gas-phase dynamics inside the rotor channels. That includes preferential bubble paths and zones of agglomeration, gas pocket formation, coalescence and breakup, and the effect of flow pattern transition on different degrees of performance degradation that centrifugal rotors are subject to when working with gas–liquid flows. Also, important information about the effect of the gas flowrate and the rotating speed on the performance of the assumed rotor prototype could be gathered. Discussions in this work should contribute to comprehend the behavior of gas–liquid flow in centrifugal pumps, a topic that is still far from being well understood. Qualitative and quantitative data here presented could also be valuable to guide the development of numerical models to solve this problem.

Experimental Visualization of Gas-Liquid Flow Patterns in a Centrifugal Rotor

2019 ◽  
Author(s):  
Henrique Stel ◽  
Edgar Minoru Ofuchi ◽  
Rafael Fabrício Alves ◽  
Sergio Chiva ◽  
Rigoberto E. M. Morales
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Volume Fraction ◽  
Flow Patterns ◽  
Centrifugal Pumps ◽  
Gas Volume Fraction ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Complex Phenomena ◽  
Gas Volume

Abstract Centrifugal pumps operating with gas-liquid flows can undergo severe performance degradation. This can be attributed to an effect of the gas phase on the liquid flow orientation in the pump impeller channels, which induces additional hydraulic losses that negatively affect the delivered head and flow rate. Effort to investigate the effect of many operating parameters on the pump performance under multiphase flows can be found on numerous experimental investigations. Few studies, however, bring together flow visualization to understand the physics behind the behavior of centrifugal pumps with gas-liquid flows. One issue is that pumps involve rotating parts, metallic casing and limited visual access, sometimes making it hard to interpret flow patterns and to understand complex phenomena, such as bubble breakup and coalescence. Such issues usually lead to unsatisfactory image quality, which in turn makes it difficult to extract quantitative data from the obtained images, such as gas volume fraction and bubble size distribution. In an attempt to overcome many difficulties of previous investigations, this work presents an experimental study aimed to visualize gas-liquid flow patterns in a centrifugal rotor prototype using a novel approach. The experimental apparatus uses a plane and transparent rotor, assembled with an intake pipe and a discharge chamber by means of a dynamic seal system that dismisses the use of an enclosing pump casing. This makes possible to use back illumination of the impeller for visualization, which in turn is done by using a camera attached to the impeller axis for filming in a rotating frame of reference. This setup, which is new in the open literature, provides high image contrast and sharpness for clear interpretation of the flow patterns found inside the rotor channels for a wide range of operating conditions. This advantage, in turn, allows using image processing for quantitative assessment of gas volume fraction distributions. Pressure rise versus flow rate curves are measured together to investigate the rotor performance degradation associated with the gas-liquid flow patterns for a range of liquid and gas flow rates. Information obtained with the designed experimental setup at controlled conditions help not just to bring further understanding to the complex phenomena involved with multiphase flows in rotating devices, but also in the direction of validating a numerical model for reliable simulations of gas-liquid flows in centrifugal pumps, which is lacking in the current literature.

Sign in / Sign up

Export Citation Format

Share Document