scholarly journals Dynamics and mass transfer of rising bubbles in a homogenous swarm at large gas volume fraction

2014 ◽  
Vol 763 ◽  
pp. 254-285 ◽  
Author(s):  
Damien Colombet ◽  
Dominique Legendre ◽  
Frédéric Risso ◽  
Arnaud Cockx ◽  
Pascal Guiraud
Keyword(s):  
Mass Transfer ◽  
High Speed ◽  
Bubble Dynamics ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Optical Probe ◽  
Bubble Velocity ◽  
Gas Volume Fraction ◽  
Bubble Rising ◽  
Gas Volume

AbstractThe present work focuses on the collective effect on both bubble dynamics and mass transfer in a dense homogeneous bubble swarm for gas volume fractions${\it\alpha}$up to 30 %. The experimental investigation is carried out with air bubbles rising in a square column filled with water. Bubble size and shape are determined by means of a high-speed camera equipped with a telecentric lens. Gas volume fraction and bubble velocity are measured by using a dual-tip optical probe. The combination of these two techniques allows us to determine the interfacial area between the gas and the liquid. The transfer of oxygen from the bubbles to the water is measured from the time evolution of the concentration of oxygen dissolved in water, which is obtained by means of the gassing-out method. Concerning the bubble dynamics, the average vertical velocity is observed to decrease with${\it\alpha}$in agreement with previous experimental and numerical investigations, while the bubble agitation turns out to be weakly dependent on ${\it\alpha}$. Concerning mass transfer, the Sherwood number is found to be very close to that of a single bubble rising at the same Reynolds number, provided the latter is based on the average vertical bubble velocity, which accounts for the effect of the gas volume fraction on the bubble rise velocity. This conclusion is valid for situations where the diffusion coefficient of the gas in the liquid is very low (high Péclet number) and the dissolved gas is well mixed at the scale of the bubble. It is understood by considering that the transfer occurs at the front part of the bubbles through a diffusion layer which is very thin compared with all flow length scales and where the flow remains similar to that of a single rising bubble.

scholarly journals Homogeneous swarm of high-Reynolds-number bubbles rising within a thin gap. Part 1. Bubble dynamics

2012 ◽  
Vol 704 ◽  
pp. 211-231 ◽  
Author(s):  
Emmanuella Bouche ◽  
Véronique Roig ◽  
Frédéric Risso ◽  
Anne-Marie Billet
Keyword(s):  
Bubble Dynamics ◽  
Volume Fraction ◽  
Vertical Direction ◽  
Wall Friction ◽  
Bubble Velocity ◽  
Velocity Statistics ◽  
Velocity Variance ◽  
Gas Volume Fraction ◽  
Gas Volume ◽  
Bubble Agitation

AbstractThe spatial distribution, the velocity statistics and the dispersion of the gas phase have been investigated experimentally in a homogeneous swarm of bubbles confined within a thin gap. In the considered flow regime, the bubbles rise on oscillatory paths while keeping a constant shape. They are followed by unstable wakes which are strongly attenuated due to wall friction. According to the direction that is considered, the physical mechanisms are totally different. In the vertical direction, the entrainment by the wakes controls the bubble agitation, causing the velocity variance and the dispersion coefficient to increase almost linearly with the gas volume fraction. In the horizontal direction, path oscillations are the major cause of bubble agitation, leading to a constant velocity variance. The horizontal dispersion, which is lower than that in the vertical direction, is again observed to increase almost linearly with the gas volume fraction. It is however not directly due to regular path oscillations, which are unable to generate a net deviation over a whole period, but results from bubble interactions which cause a loss of the bubble velocity time correlation.

Stability Criteria of the Steady Flow of a Liquid Containing Bubbles Along a Nozzle

2001 ◽  
Vol 123 (4) ◽  
pp. 836-840 ◽  
Author(s):  
A. Crespo ◽  
J. Garcı´a ◽  
J. Jime´nez-Ferna´ndez
Keyword(s):  
Bubble Dynamics ◽  
Volume Fraction ◽  
Flow Instability ◽  
Functional Dependence ◽  
Bubble Diameter ◽  
Critical Value ◽  
Stability Criteria ◽  
Flow Through ◽  
Gas Volume Fraction ◽  
Gas Volume

The steady cavitating flow through a converging-diverging nozzle is considered. A continuum model is assumed with the Rayleigh-Plesset equation to account for the bubble dynamics. A similar problem has been studied previously by Wang and Brennen, and they found that if the upstream gas volume fraction of the bubbles exceeds a critical value there is flashing flow instability. In the present work, a perturbation analysis is made introducing a small parameter, ε, that is the ratio of the initial bubble diameter to the length scale of the nozzle. As a result of this analysis, the critical value of the upstream void fraction is calculated as a function of the several parameters appearing in the problem, and turns out to be very small and proportional to ε3. A correlation is proposed giving explicitly the functional dependence of this critical value.

scholarly journals The Drag Forces on a Taylor Bubble Rising Steadily in Vertical Pipes

2021 ◽  
Vol 3 (4) ◽  
pp. 1-1
Author(s):  
Abdullah Abbas Kendoush ◽  
Keyword(s):  
Volume Fraction ◽  
Bond Number ◽  
Water Systems ◽  
Taylor Bubble ◽  
Drag Forces ◽  
Wide Range ◽  
Gas Volume Fraction ◽  
Bubble Rising ◽  
Gas Volume ◽  
Comparison With Experimental Data

By the adoption of a drag-buoyancy equality model, analytical solutions were obtained for the drag coefficients (CD) of Taylor bubbles rising steadily in pipes. The obtained solutions were functions of the geometry of the Taylor bubble and the gas volume fraction. The solutions were applicable at a wide range of Capillary numbers. The solution was validated by comparison with experimental data of other investigators. All derived drag formulas were subject to the condition that Bond number >4, for air-water systems.

Numerical Simulation of High-Speed Cavitating Water-Jet Issuing From a Submerged Nozzle

2012 ◽  
Author(s):  
Guoyi Peng ◽  
Hideto Ito ◽  
Seiji Shimizu
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Volume Fraction ◽  
Water Jet ◽  
Cavitation Number ◽  
Local Flow ◽  
Bubble Liquid ◽  
Bubble Cavitation ◽  
Gas Volume Fraction ◽  
Gas Volume

A simplified estimation for the compressibility of cavitating flow is proposed based on the bubble cavitation model and a compressible mixture flow method is developed for the numerical simulation of high-speed cavitating jet by coupling the simplified estimation of bubble cavitation to a compressible turbulent flow computation procedure. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase, which is governed by the compressibility of bubble-liquid mixture at the current status of local flow field. The method is applied to the simulation of high-speed submerged water jets issuing from an orifice nozzle. Both non-cavitating and cavitating jets are calculated under different cavitation numbers in order to clarify the cavitation property of submerged water jet. The results demonstrate that the intensity of cavitation denoted by the maximum value of gas volume fraction and the area of strong cavitation indicted by high value of gas volume fraction increase with the decrease of cavitation number. Under the effect of cavitation bubbles the discharge coefficient of orifice nozzle decreases with the cavitation number.

Qualification of a New Multiphase Pump. the Setting of a New Standard

2021 ◽  
Author(s):  
Åge Hofstad ◽  
Tarje Olderheim ◽  
Magnus Almgren ◽  
Marianna Rondon ◽  
Edouard Thibaut ◽  
...  
Keyword(s):  
High Speed ◽  
Oil And Gas ◽  
Volume Fraction ◽  
Two Phase ◽  
Specific Product ◽  
Multiphase Pump ◽  
Gas Volume Fraction ◽  
Gas Market ◽  
Gas Volume ◽  
Winding Insulation

Abstract The recent trend in the oil industry is to save CAPEX and exploit every offshore field to increase production and maximize reserves. Also, deeper water and longer step-out is a challenge for new fields. The most adapted technology to unlock these reserves is the use of subsea boosting like a multiphase pump on the seafloor. Subsea boosting has been used for decades with well proven results, but up to now, some limitations in power and lift pressure exist. This new multiphase pump development has increased the potential pressure generation manyfold from the typical ΔP of 50 bar (725 psi) at the beginning of the project. Developing such a powerful two-phase pump driven by a liquid-filled motor requires a unique combination of expertise in machinery engineering, electrical engineering, fluid mechanics and rotor dynamics. The objective of the co-authors is to share this experience by bringing some insights on what it takes to develop, test, and qualify such specific product. Outlines of the methodology will be described, key results will be detailed, and lessons learnt will be presented. The new design was fully tested first component-wise and then for a full-size prototype. A wide process envelope was mapped during the final qualification program with 3,000 points tested in the range 2,000-6,000 RPM and 0 - 100% GVF (Gas Volume Fraction). Qualification tests concluded with more than 2,000 cumulative hours. The main challenges in this program were the development of an innovative multiphase impeller and the qualification of the first MPP (MultiPhase Pump) with a back-to-back configuration. Concerning the motor, the development includes a high speed 6,000 RPM, 6 MW liquid-filled induction motor and a new stator winding insulation cable. With this new product, the pump market is ready to overcome challenges to produce deeper and further reservoirs in a constant evolutive oil and gas market.

Temporal Gas Volume Fraction and Bubble Velocity Measurement Using an Impedance Needle Probe

2013 ◽  
Author(s):  
Sahand Pirouzpanah ◽  
Gerald L. Morrison
Keyword(s):  
Oil And Gas ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Oil And Gas Industry ◽  
Bubble Velocity ◽  
Time Interval ◽  
Needle Probe ◽  
Measured Time ◽  
Gas Volume Fraction ◽  
Gas Volume

Impedance probes are used by the oil and gas industry to investigate multiphase flow behavior. In this study, an impedance needle probe has been developed to measure the local and temporal gas volume fraction in conductive and non-conductive process fluid. Measuring both resistance and capacitance enables this probe to be functional in both types of fluids and facilitates the measurement of local bubble velocity. Two 1/32″ insulated brass (alloy 260) rods with bare tips protrude into the flow. The gap between the electrodes is designed to be 0.085″. The probe can measure directional bubble velocity by measuring duration of signal gradient from liquid to gas transition. For a known distance between electrodes and by the measured time, directional bubble velocity in the direction of the connecting line between electrodes can be measured. The ratio between the time interval when signal is non-zero to the total time represents the temporal gas volume fraction.

Numerical Investigation on the Structure of High-Speed Cavitating Water Jet Issuing From an Orifice Nozzle

2011 ◽  
Author(s):  
Guoyi Peng ◽  
Hideto Ito ◽  
Seiji Shimizu ◽  
Shigeo Fujikawa
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Water Jet ◽  
Cavitation Number ◽  
Mean Flow ◽  
Mixture Flow ◽  
Gas Volume Fraction ◽  
The Mean ◽  
Gas Volume

A practical mixture flow approach to the numerical simulation of turbulent cavitating flows is developed by coupling a simplified estimation of bubble cavitation to a compressible mixture flow computation. The mean flow of two-phase mixture is calculated by neglecting the slip between bubbles and surround liquid. Navier-Stokes equations for compressible fluids are used to describe the unsteady mean flow field and the RNG k-ε model is adopted for modeling of the flow turbulence. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the mean flow. The flow structure of submerged water jets issuing from an orifice nozzle is investigated numerically. Both non-cavitating and cavitating jets are calculated under different cavitation numbers in order to clarify the cavitation property of submerged water jet. The results demonstrate that the intensity of cavitation denoted by the maximum value of gas volume fraction and the area of strong cavitation indicted by high value of gas volume fraction increase with the decrease of cavitation number. Under the effect of cavitation bubbles the discharge coefficient of orifice nozzle decreases with the cavitation number.

scholarly journals Effect of the Gas Volume Fraction on the Pressure Load of the Multiphase Pump Blade

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 650
Author(s):  
Guangtai Shi ◽  
Dandan Yan ◽  
Xiaobing Liu ◽  
Yexiang Xiao ◽  
Zekui Shu
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Volume Fraction ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Multiphase Pump ◽  
Pressure Load ◽  
Gas Volume Fraction ◽  
Power Capability ◽  
Gas Volume

The gas volume fraction (GVF) often changes from time to time in a multiphase pump, causing the power capability of the pump to be increasingly affected. In the purpose of revealing the pressure load characteristics of the multiphase pump impeller blade with the gas-liquid two-phase case, firstly, a numerical simulation which uses the SST k-ω turbulence model is verified with an experiment. Then, the computational fluid dynamics (CFD) software is employed to investigate the variation characteristics of static pressure and pressure load of the multiphase pump impeller blade under the diverse inlet gas volume fractions (IGVFs) and flow rates. The results show that the effect of IGVF on the head and hydraulic efficiency at a small flow rate is obviously less than that at design and large flow rates. The static pressure on the blade pressure side (PS) is scarcely affected by the IGVF. However, the IGVF has an evident effect on the static pressure on the impeller blade suction side (SS). Moreover, the pump power capability is descended by degrees as the IGVF increases, and it is also descended with the increase of the flow rate at the impeller inlet. Simultaneously, under the same IGVF, with the increase of the flow rate, the peak value of the pressure load begins to gradually move toward the outlet and its value from hub to shroud is increased. The research results have important theoretical significance for improving the power capability of the multiphase pump impeller.

Sign in / Sign up

Export Citation Format

Share Document