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Dissertations / Theses on the topic 'Two- and three-phase flow'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

Sukarno, Pudjo. "Inflow performance relationship curves in two-phase and three-phase flow conditions /." Access abstract and link to full text, 1986. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/8614191.

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2

Akbar, Muhammad Khalid. "Transport Phenomena in Complex Two and Three-Phase Flow Systems." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4897.

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Two and three-phase flow processes involving gas, liquid and solid, are common in nature and industry, and include some of the most complex and poorly-understood transport problems. In this research hydrodynamics, heat and mass transfer processes in complex two and three-phase flows were investigated. The interfacial surface area concentration in a short vertical column subject to the through flow of fiber-liquid-gas slurry was experimentally measured using the gas absorption technique. The experimental data were statistically analyzed for parametric effects, and were empirically correlated. The absorption of a gaseous species by a slurry droplet with internal circulation and containing reactive micro-particles was simulated, and parametrically studied. The micro-particles were found to enhance the absorption rate. The absorption rate was sensitive to droplet recirculation, and shrinkage of particles with time resulted in declining absorption rates. The transport of soot particles, suspended in laminar hot gas flowing in a tube, was modeled and parametrically studied. Due to coupled thermal radiation and thermophoresis, a radially-nonuniform temperature profile develops, leading to sharp, non-uniform radial soot-concentration profiles. The assumption of monodisperse particles leads to over-prediction of thermophoresis. The transport and removal of particles suspended in bubbles rising in a stagnant liquid pool were modeled based on a Eulerian – Monte Carlo method. The bubble hydrodynamics were treated in Eulerian frame, using the Volume-of-Fluid (VOF) technique, while particle equations of motion were numerically solved in Lagrangian frame. The bubbles undergo shape change, and have complex internal circulation, all of which influence the particle removal. Model predictions were also compared with experimental data. Using a resemblance between two-phase flow in microchannels, and in large channels at microgravity, a simple Weber number-based two-phase flow regime map was developed for microchannels. Based on the available air-water experimental data, a criterion for the prediction of conditions that lead to flow regime transition out of the stratified-wavy flow pattern in horizontal annular channels was proposed. The thermocapillary effects on liquid-vapor interface shape during heterogeneous bubble ebullition in microchannels were analytically studied.

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3

Kunda, Wilkinson. "Two phase problems and two phase flow." Thesis, University of Hull, 1986. http://hydra.hull.ac.uk/resources/hull:5902.

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In section 1 of this thesis a two-dimensional mathematical model is used to investigate the circulation in a gas-bubble agitation system of a cylindrical vessel for the case of an orifice located at the centre of the base. The two-phase (liquid/gas) region is assumed to be confined to a cone-shaped region and is investigated using Wallis' Drift Flux Model. In the single-phase (liquid) region the turbulent Navier-Stokes equations, written in terms of the stream function, are used for the mathematical model. The analysis in the two-phase region yields the boundary conditions on the two-phase/single-phase boundary. The velocity field in the two-phase region is solved analytically giving results in closed form. A numerical algorithm is developed for calculating liquid flow in the single phase region, and numerical results are presented graphically in terms of the stream function. In section 2 two moving interface problems are investigated. Small time analytic solutions are found for three-dimensional inward solidification of a half space initially at fusion temperature in the first problem. In the second problem, perturbation solutions for melting of a cylindrical annulus with constant heat flux on inner surface are given. In both problems the interface immobilization technique is used. Interface locations at various times are calculated for the inward solidification problem and the results shown in three-dimensional graphs. First and second perturbation terms for the interface location are given for the second problem and graphs of each are presented for a particular case.

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4

Rapisarda, Andrea. "Hydrodynamic characterization of two/three phase flow regimes in stirred tank." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

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Questo progetto di ricerca riguarda i processi di miscelazione in sistemi multifase meccanicamente agitati(regime turbolento). I sistemi studiati sono: gas-liquido, solido-liquido e gas-solido-liquido. Lo scopo è quello di analizzare il movimento delle particelle solide all'interno di un recipiente agitato, calcolandone la velocità(n) alle quali si è ottenuto lo stato di estrazione delle particelle(nJD), della completa dispersione(nCD) e del loading(nloading), attraverso l'uso di due diversi valori di diametro delle particelle. Le misure sono state effettuate utilizzando due giranti su un albero e condotte con 6 diverse portate di gas e (da 3 a 6) concentrazioni X di particelle solide. La presente ricerca dimostra che i valori di nloading non dipendono dalla concentrazione X di particelle nel sistema con acqua come fase liquida per entrambi i diametri di particelle dp, nel sistema con 0.4 Kmol/m3 di NaCl per dp1 e nel sistema con 0.8 Kmol/m3 di NaCl per dp2. Nei sistemi con acqua e 0.4 Kmol/m3 di NaCl come fase liquida, i valori di nCD aumentano con l'aumento della concenrtrazione di particelle. I valori di nJD aumentano significamente con l'aumento della concentrazione solida, per entrambi i diametri di particelle nel sistema a coalescenza(con acqua) e non coalescenza con concentrazione di elettrolita 0.8 Kmol/m3 di NaCl. La stessa dipendenza di nJD=f(X) è osservata per 0.4 Kmol/m3 di NaCl per dp2. Per l'intera gamma di concentrazioni solide X, per lo stesso valore ddel diametro delle particelle, si ottengono valori inferiori di velocità di nloading, nCD, nJD per la configurazione delle giranti CD6-PBT.

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5

Ahmadi, Motlagh Amir Hossein. "CFD simulation of two- and three-phase flow in FCC reactors." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52621.

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Liquid distribution and evaporation in Fluid Catalytic Cracking (FCC) reactors are investigated numerically. The well-documented inaccuracy of conventional two-fluid modeling of hydrodynamics in fluidized beds of Geldart Group A particles is revisited. A new force-balance (FB) sub-grid-scale model, introduced and applied to the conventional Wen-Yu drag correlation, analyzes the balance of van der Waals, drag, gravity and buoyancy forces. It predicts formation of agglomerates inside the bed, updating the drag calculations by applying a correction factor to the conventional drag models. Good predictions are obtained of fluidization regimes and bed expansion, and there is promising agreement with experimental time-average radial voidage profiles reported by Dubrawski et al. (2013). Good quantitative agreement between discrete element models (DEM) and two-fluid predictions of minimum bubbling velocity is also observed when the model is used to predict minimum bubbling velocity, in contrast to the predictions from a non-cohesive, Wen-Yu model. Liquid injection experiments on a lab-scale fluidized bed were conducted, at the Institute of Chemical and Fuels from Alternative Sources (ICFAR) in London, Ontario to study the distribution, as well as the penetration, of liquid into catalyst pores. The results shed light on complexities involved in the injection zone to understand the effect of superficial gas velocity on evaporation and imbibition of liquid into particle pores. A methodology is developed to couple and incorporate existing liquid imbibition (into particle pores) models with evaporation models in the CFD code. The results are compared to another set of lab-scale experiments conducted at the British Columbia Research Institute (BCRI) facilities in Burnaby, BC. Simulation results demonstrate that CFD models can capture correct qualitative behavior of liquid injection and evaporation inside the bed. However, quantitative deviations revealed the likely effect of hydrodynamic properties on drying from both the liquid film around the particles and inside the pores. The deviations also imply that the assumption of convection- or diffusion-dominant drying might be unsuitable, and the two should be combined. Based on experimental results, a methodology is proposed to include the effect of hydrodynamic properties such as superficial gas velocity and particle impact velocity on drying.<br>Applied Science, Faculty of<br>Chemical and Biological Engineering, Department of<br>Graduate

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6

Jahanbakhsh, Amir. "Two- and three-phase flow functions for numerical simulation of EOR processes." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3218.

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The understanding of governing mechanisms of multi-phase (oil, water, and gas) flow in porous media is of keen interest in petroleum and environmental engineering. In the petroleum engineering context, three-phase flow occurs in several important processes including in enhanced oil recovery (EOR). Recovery of a significant amount of the residual oil in reservoirs after primary recovery and secondary recovery (waterflooding) is important in order to tackle the increasing demand for the energy. EOR methods mainly involve two and three-phase flow in the reservoir. Relative permeability (kr) and capillary pressure (Pc) are two important parameters in multiphase flow which describe the interaction of each fluid in porous media. The importance of these flow functions will be even more significant for three-phase flow systems. This thesis attempts to address three key issues. (i) Improved determination of multi-phase flow functions (kr and Pc). (ii) The impact of parameters affecting flow functions. (iii) Prediction of multi-phase flow functions. Relative permeability (kr) can be measured in the laboratory using steady-state and unsteady-state methods, or estimated by mathematical correlations and pore-network models. As multi-phase flow experiments and in particular steady-state measurements are very time consuming and expensive, more often the unsteady-state method is used for multi-phase kr measurements. In this thesis, a methodology has been devised for calculating kr values and in particular three-phase kr from unsteady-state experiments. The effort was extended to simultaneously calculating Pc from the same coreflood experiment. There are different physical parameters which can affect flow functions. The effect of gas/oil interfacial tension (IFTg/o) on two and three-phase kr and also on residual saturation during alternative water and gas injections has also been studied. Finally, two-phase kr have been estimated for rock and fluid conditions where there is no previous data. This has been achieved by taking data from different conditions under which measurements were made.

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7

Malhotra, Ajay. "Study of two and three-phase flows in large diameter horizontal pipelines." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179947127.

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8

Ariyoshi, Gen. "Flow Characteristics of Lead-Bismuth Two-phase Flow." Kyoto University, 2019. http://hdl.handle.net/2433/242325.

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9

Makhlouf, Eliana Mary Seinfeld John H. Seinfeld John H. "Estimation of absolute permeability in multilayered petroleum reservoirs with two- and three-phase flow /." Diss., Pasadena, Calif. : California Institute of Technology, 1990. http://resolver.caltech.edu/CaltechETD:etd-03162007-091347.

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10

Isaacs, Steven. "Two-phase flow and heat transfer in pin-fin enhanced micro-gaps." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50282.

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In modern microprocessors, thermal management has become one of the main hurdles in continued performance enhancement. Cooling schemes utilizing single phase microfluidics have been investigated extensively for enhanced heat dissipation from microprocessors. However, two-phase fluidic cooling devices are becoming a promising approach, and are less understood. This study aims to examine two-phase flow and heat transfer within a pin-fin enhanced micro-gap. The pin-fin array covered an area of 1cm x 1cm and had a pin diameter, height and pitch of 150μm, 200μm and 225μm, respectively, (aspect ratio of 1.33). This study covers both uniformly and partially heated scenarios. The working fluid used was R245fa. The average heat transfer coefficient and high speed flow visualization results indicated a rapid transition to the annular flow regime with a strong dependence on heat flux. Also, unique, conically-shaped two-phase wakes were observed, demonstrating the lateral spreading capability of the pin-fin array geometry.

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11

Whitaker, T. S. "Measurement of two-phase flows by phase separation." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240831.

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12

Dillon, Chad Michael. "Two-Phase Flow Within Narrow Annuli." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5097.

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A study of two-phase flow in annular channels with annular gaps of less than 1 mm is useful for the design and safety analysis of high power density systems such as accelerator targets and nuclear reactor cores. Though much work has been done on pressure drop in two-phase flow, designers rely mostly on empirical models and correlations; hence, it is valuable to study their applicability for different channel sizes, geometries, and gas qualities. The pressure drop along a concentric annular test section was measured for cases of either constant quality or variable quality along its length (such as in sub-cooled and flow boiling). A porous tube was used to inject gas along the inner surface of the annular channel, thereby simulating the case of flow boiling along the inner surface. The data were compared to predictions of various models and correlations. Additionally, the effect of wall vibrations on the pressure drop was examined. Experiments were conducted by imposing vibrations of known amplitudes and frequencies on the outer tube of the annulus. Wall vibrations were thought to be important for flow in microchannels where the vibration amplitudes may be significant compared to the channel hydraulic diameter. The results obtained in this investigation indicate that the pressure drop correlation given by Beattie and Whalley provides the best agreement with the data for both porous tube gas injection (i.e. variable quality) and constant quality two-phase flow within the narrow annulus. Furthermore, the results show that there is a minimal effect of vibrations on two-phase pressure drop over the range of frequencies and amplitudes studied.

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13

Lillibridge, Kris Hamilton. "Buoyancy-driven two-phase countercurrent flow." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16027.

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14

Neuweiler, Insa. "Macroscopic parameters for two-phase flow." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13490.

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15

Sharma, Yugdutt. "Modeling transient two-phase slug flow /." Access abstract and link to full text, 1985. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/8605319.

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16

McQuillan, K. W. "Flooding in annular two-phase flow." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354843.

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17

Willetts, I. P. "Non-aqueous annular two-phase flow." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393120.

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18

Klidonas, G. "Void fraction in two phase flow." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235032.

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19

Stewart, Colin. "Metering of two-phase slug flow." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21158.

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This thesis describes the development of a novel system, for metering of two-phase (gaswater) slug flows. The approach combines a model for stable slug flow, a non-intrusive set of conductance sensors, and appropriate closure relationships. This system allows each of the parameters in the model to be determined. The slug flow model is analysed, to determine the sensitivity of the phase flowrates to each measurement parameter. A metering system is then proposed which combines ring-shaped electrodes, electronic instrumentation, and processing software. The ring electrodes are optimised, for the measurement of the phase fraction and the translation velocity. New instrumentation is developed to activate the electrodes, with high measurement accuracy and a wide bandwidth. Analysis software is developed, to process the sensor data, provide suitable closure relations, and deliver the flowrates. A unique feature of this software is its ability to calculate uncertainty margins in the predicted flowrates. The NEL multiphase facility is used, to obtain data for developed, horizontal, gas-water slug flow in a 4-inch pipe. The data span the range of liquid phase superficial velocities 0.1 m s⁻¹ to 1.0 m s⁻¹, and gas phase superficial velocities 0.6 m s⁻¹ to 6.0 m s⁻¹. The analysis software is used to obtain the flowrate predictions and estimates for the uncertainty margins. The stable slug flow model does not give good results. The relative error in the gas phase prediction is between 10% and 100%, and for the liquid phase prediction, between 50% and 500%. The uncertainty margins are also of comparable magnitude. Proposals for improving the accuracy of the translation velocity measurement, and for directly measuring the local velocities in the slug body (using a pressure transducer) are presented. These proposals aim to reduce the uncertainty that is caused by the use of the empirical closure relationships in the model.

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20

Roberts, Paul Anthony. "Two-phase flow at T-junctions." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240490.

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21

Velat, Christopher James. "Experiments in cryogenic two phase flow." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0006941.

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22

Srichai, Somprasong. "High pressure separated two-phase flow." Thesis, Imperial College London, 1994. http://hdl.handle.net/10044/1/8656.

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23

Teixeira, Jose Carlos Fernandes. "Turbulence in annular two phase flow." Thesis, University of Birmingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.570318.

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The structure of turbulent flow in vertical upwards annular air water two-phase flow was examined. Experiments were carried out in a 32 mm internal diameter tube using laser Doppler anemometry. Simultaneous measurements of the two velocity components and the Reynolds stress were obtained by the use of two colours (blue and green) of a 50 mW argon ion laser. The gas core was seeded by polystyrene particles of 1 um diameter which were believed to follow the gas turbulent fluctuations. The characteristics of the signal were used to discriminate these tracer particles from the water droplets. The gas velocity profiles were shown to be more peaked at the centre of the tube than those observed in turbulent single phase flow. Comparative analysis with other data suggested that both interfacial roughness and, particularly, the momentum interchange between the droplets and the gas core, are the most important factors affecting the gas velocity profile in annular flow. Turbulent fluctuations of the gas velocity were found to be significantly higher than those typical of single phase flow, for similar gas Reynolds numbers. The interfacial shear, droplet size and concentration and the presence of disturbance waves at the interface were identified as being the most important factors affecting the gas turbulence in annular flow. A model was developed to predict the axial component of the turbulent fluctuations at the centre of the tube. The turbulence transport properties were observed to differ from those typical of single phase flow: i.e., higher production of turbulent energy (associated with higher anisotropy ratios), higher turbulence length scales and comparativelly lower dissipation ratios. Extrapolation of the mixing length theory to annular flow appeared to be inappropriate. Droplet size measurements showed that the gas velocity and the droplet concentration are the most important parameters affecting droplet size. At low droplet concentrations (where the gas-droplet interaction is more important than that between the droplets), a modified Weber number based on the homogeneous gas core momentum describes the maximum droplet diameter. At high droplet concentrations, the data suggests that coalescence is the dominant factor. Droplet velocity was found to be related to the size of the droplets: i.e., large droplets travel slower than small ones. The difference in velocity between large and small droplets was found to depend on the liquid and gas flow rates. This observation is related to conditions where droplet coalescence occurs. The effect of inserts on droplet size and the entrained fraction was examined. Disturbances in the channel geometry were found to affect the mean droplet size due to the creation of a new droplet population. The entrained fraction of liquid downstream of the insert was also affected. A model was formulated to describe the liquid interchange in the presence of a vertical plate.

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24

Galambos, Paul C. "Two-phase dispersion in micro-channels /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/7100.

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25

Lei, Siu Long. "Phase-field simulations of two-phase flows /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?MATH%202009%20LEI.

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26

Zschuppe, Robert. "Pulse Flow Enhancement in Two-Phase Media." Thesis, University of Waterloo, 2001. http://hdl.handle.net/10012/1267.

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This laboratory project has been done to evaluate pressure pulsing as an Enhanced Oil Recovery (EOR) technique. To perform the study, a consistent laboratory methodology was developed, including the construction of a Consistent Pulsing Source (CPS). Tests compared pulsed and non-pulsed waterfloods in a paraffin or crude oil saturated medium, which also contained connate water (an irreducible water saturation). Results revealed that pulsed tests had maximum flow rates 2. 5--3 times higher, greater oil recovery rates, and final sweep efficiencies that were more than 10% greater than non-pulsed tests. The CPS design has proven very successful, and has since been copied by a major oil corporation. However, there are two limitations, both caused by fluctuating water reservoir levels. Longer pulsed tests (reservoir-depletion tests) were periodically paused to refill the water reservoir, resulting in reservoir depressurization and lower flow rates. The final effect of this was impossible to quantify without correcting the problem. The second CPS limitation was the change in pulse shape with time. However, it is not expected that this had any major effect on the results. The pulse pressure and period studies were limited by early tests, which did not have the necessary time duration. Both increasing pulse pressure and decreasing pulse period were found to increase the final sweep efficiency. Slightly decreasing porosity (0. 4% lower) was found to lower sweep efficiencies. However, the 34. 9% porosity results were not done until reservoir depletion, so it is difficult to quantitatively compare results. An emulsion appeared after water breakthrough when using the CPS on light oils (mineral oil). This may have been the result of isolated oil ganglia being torn apart by the sharp pulses. Although it is difficult to apply laboratory results to the field, this study indicates that pressure pulsing as an EOR technique would be beneficial. Doubled or tripled oil recovery rates and 10% more oil recovery than waterflooding would be significant numbers in a field operation. A valuable application would be in pulsing excitation wells to both pressurize the reservoir and enhance the conformance of the displacing fluid over a long-term period. It would also be valuable for short-term chemical injections, where mixing with the largest volume possible is desirable.

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27

Ekberg, Nathanial Paul. "Two-phase flow in horizontal thin annuli." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17250.

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28

Du, Xiaoju. "Numerical Solvers for Transient Two-Phase Flow." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23608.

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Certain numerical methods have been well developed for solving one-dimensional two-phase flow (e.g. gas and liquid) problems in the literatures during the last two decades. Based on the existing methods, the present work compares the computational efficiency, accuracy, and robustness of various numerical schemes by predicting the numerical solutions of fluid properties for a specific case to find the proper numerical method. One of the numerical schemes introduced in this work is a practical, semi-implicit upwind method used for fluid flow simulations in different flow patterns,stratified flow and slug flow. This method implements the iterative and non-iterative schemes using a two-fluid model that consists of sets of non-hyperbolic equations. A numerical error term is applied in the pressure equation to maintain the volume balance of the two-phase flow model. If the temperature varies, the discretised energy equations use similar error terms as in the pressure equation. In some cases, the small values of the numerical errors are negligible and do not influence the numerical results. These errors are, however, important factors to consider when maintaining the stability and robustness of the above numerical schemes for strong non-linear cases. The computational efficiency ofthe non-iterative scheme, where the inner iterations are deactivated, is better than the iterative scheme. Different grid arrangements are compared with respect to computational accuracy and efficiency. A staggered structured grid implements the same semi-implicit upwind method as in the non-iterative scheme; the non-staggered grid arrangement uses an existing flux-splitting scheme (Evje and Flåtten, 2003) as a reference. All the above schemes produce numerical solutions with a single precision that normally satisfy the requirements of computational accuracy of industrial two-phase pipe flows. However, if one pursues a higher-order accuracy scheme, e.g. a Roe-averaged algorithm, the governing equations should be strictly a hyperbolic system of partial differential equations, which is achieved by introducing the nonviscous force terms in the two-fluid model (LeVeque, 2002).By properly incorporating the non-conservative terms in the formulation of the numerical fluxes, the capability of the Roe-averaged algorithm is demonstrated by capturing shock waves. Results from the present research include the following. A one-dimensional scheme that solves a system of discretised equations with the staggered semi-implicit upwind method is presented and validated for its computational efficiencyand robustness. This scheme can be widely used in the industry with sufficient accuracy. The other first-order semi-implicit numerical schemes producestable numerical results, especially in the dynamic cases of two-phase flow, except when the gas phase nearly disappears or appears in pipes. The Roe-averaged algorithm is recommended due to the high-resolution numerical results obtained, but at the costs of computational time and effort.

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Pan, Xuefeng. "Immiscible two-phase flow in a fracture." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0025/NQ47907.pdf.

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30

Olsson, Elin. "Mass Conserving Simulations of Two Phase Flow." Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3851.

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31

Sachdeva, Rajesh. "Two-phase flow through electric submersible pumps /." Access abstract and link to full text, 1988. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9021070.

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32

Rahbari, Ahmadreza. "Dynamic two phase flow models for flushing." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26320.

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This thesis aims at modeling the separated liquid-liquid flows with application for flushing. In the beginning, there will be a short review of the governing equations and the fundamental concepts used in this thesis. Two models are introduced and developed based on two previous PhD dissertations from NTNU(Trygve Wangensteen and Tor Kindsbekken Kjeldby). The properties of the fluids in these models are based on Oil, Exxsol D80, mu_o=1.79 [cP] and tapped water, mu_w=1.11 [cP]. These models will be numerically developed for both dynamic and stationary flows. The numerical scheme used for these models is explicit. A complete explanation about discretization is given in chapter 4.After developing the dynamic and stationary solutions for both models, there will be two major case studies. The first one is to understand when the dynamic and stationary solutions depart from one another as the mixture velocity varies between low velocities to high velocities. It turns out that The solutions look quite similar until the mixture velocity reaches the value of around U_M=1 [m/s]. Then the solutions become more and more different especially at the oil front. The second case study is about keeping the mixture velocity constant and varying the pipe angle. The pipe angle variation range lies between -2.5 and +5 degrees. For negative inclinations, the dynamic and stationary solutions agree quite well. However when the positive slope is put to the test and gravity is acting against the flow, the dynamic and stationary solutions differ more.\\Finally there will be a discussion on where this different behavior stems from. The two fluid model introduced at the beginning of this report is studied closely, term by term. These terms represent the frictional forces that balance the pressure gradient in the pipe. These forces are plotted for four different cases with mixture velocities varying from U_M=0.25 [m/s] to U_M=5 [m/s]. These figures reveal which forces dominate the solution for relatively low and high mixture velocities. The dominating forces are the ones that balance the pressure gradient. It turns out that the level gradient is quite significant and a dominant term in almost all cases. However as the mixture velocity increases, the acceleration terms grow to the same order of magnitude as the level gradient. But for the most part, the spatial and the temporal acceleration act symmetrically, and in effect cancel each other out. There will be a thorough discussion about this in the final chapter.

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33

Dai, Yunfeng. "Integration of tomographic two-phase flow measurements." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421439.

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34

Bacon, Roger Philip. "Large bubbles in downwards two-phase flow." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388824.

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35

Brown, Ian Stuart. "The compositional consequences of two phase flow." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293611.

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Yang, Xiaogang. "Two-phase flow dynamical simulations and modelling." Thesis, University of Birmingham, 1996. http://etheses.bham.ac.uk//id/eprint/1417/.

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Considerable progress in understanding and predicting two-phase flow phenomena has been advanced over the past 10 years or so using a combination of model development, computational techniques and well-designed experiments. However, there remain many modelling uncertainties mainly associated with inadequate physical prescriptions rather than with limitations of the numerical schemes. The present project addresses some of these questions, in particular in relation to dispersive transport by transient large eddies in free shear flows.

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Sweeney, Edmund J. "Water hammer transients in two-phase flow." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14518.

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Quintana, Michael Steven. "Two phase flow splitting in piping branches." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50127.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.<br>Includes bibliographical references (leaf 36).<br>The objectives of this research are to evaluate the performance of a flow-splitting tripod, discover the factors which most affect the flow distribution; and quantify the effects of geometry, quality and flow rate on the distribution. Knowing all this allows one to predict the distribution for given conditions. An R-22 test apparatus was constructed for carrying out the experiments. The factors examined were tripod orientation, Froude number, void fraction, and swirl induced by helical grooves in the tube supplying the two-phase flow to the tripod. The flow regime of concern is primarily annular. Experiments were run and data was collected and analyzed. The two piece tripods were generally found to have manufacturing defects which made their performance unpredictable. The hole through which the flow was provided was often off center. This defect greatly affected the distribution and masked other geometric factors. To eliminate this variable a number of tripods were tested, using an air-water rig, to find a tripod that was not defective. Tests using R-22 were then run on this tripod and it was found that inlet swirl had little or no affect on the flow distribution. The factors that had the greatest effect on the flow distribution were the tripod's orientation, the Froude number of the flow, and the void fraction. An empirical correlation for flow splitting was derived including these factors.<br>by Michael Steven Quintana.<br>S.M.

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Martinez, Cora E. "Eulerian-Lagrangian Two Phase Debris Flow Model." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/138.

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The main objective of this work is to develop a quasi three-dimensional numerical model to simulate stony debris flows, considering a continuum fluid phase, composed by water and fine sediments, and a non-continuum phase including large particles, such as pebbles and boulders. Large particles are treated in a Lagrangian frame of reference using the Discrete Element Method, the fluid phase is based on the Eulerian approach, using the Finite Element Method to solve the depth-averaged Navier–Stokes equations in two horizontal dimensions. The particle’s equations of motion are in three dimensions. The model simulates particle-particle collisions and wall-particle collisions, taking into account that particles are immersed in a fluid. Bingham and Cross rheological models are used for the continuum phase. Both formulations provide very stable results, even in the range of very low shear rates. Bingham formulation is better able to simulate the stopping stage of the fluid when applied shear stresses are low. Results of numerical simulations have been compared with data from laboratory experiments on a flume-fan prototype. Results show that the model is capable of simulating the motion of big particles moving in the fluid flow, handling dense particulate flows and avoiding overlap among particles. An application to simulate debris flow events that occurred in Northern Venezuela in 1999 shows that the model could replicate the main boulder accumulation areas that were surveyed by the USGS. Uniqueness of this research is the integration of mud flow and stony debris movement in a single modeling tool that can be used for planning and management of debris flow prone areas.

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Tahmasbi, Nowtarki Koroush. "Two phase hydrodynamics in cross-flow distillation." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8424.

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YAGAMI, Hisanori, and Tomomi UCHIYAMA. "Numerical Simulation of Particle-Laden Plane Mixing Layer by Three-Dimensional Vortex Method." The Japan Society of Mechanical Engineers, 2006. http://hdl.handle.net/2237/9219.

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Doup, Benjamin. "Experimental Investigation of Flow Structure Development in Air-water Two-phase Flows." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332514704.

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Abrishami-Savjublagh, Yoseph. "Numerical computations of dispersed flow and gravity stratified two-phase flow." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47736.

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Chen, Lejun. "Flow patterns in upward two-phase flow in small diameter tubes." Thesis, Brunel University, 2006. http://bura.brunel.ac.uk/handle/2438/5104.

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Two-phase flow in small tubes and channels is becoming a common phenomenon in industrial processes. However, the study of two-phase flow regimes in small tubes is still at its infancy. The previous studies are reviewed and discussed in the literature section. The problems and inconsistencies encountered in the earlier studies are presented and discussed. The experimental facility is introduced in the chapters that follow. They include a section on the design of the experimental system and the test sections, the selection of the experimental parameters and the introduction of the purposely-developed programs to control the experiments and collect and process the data. The methodology of the calibration and the uncertainty analysis, the problems encountered and their solutions and the single-phase validation experiments are also described. In this project we studied the effect of tube diameter and fluid flow parameters on flow patterns in small tubes using R134a as the working fluid. The tested tube diameters were 1.10, 2.01, 2.88 and 4.26 mm; the fluid pressures were 6, 10 and 14 bar; the liquid and gas superficial velocities covered a range of 0.04-5.0 m/s and 0.01-10.0 m/s respectively. The observed flow patterns included bubbly, dispersed bubble, confined bubble, slug, chum, annular and mist flow. Twelve integrated flow maps are sketched in this report. The obtained results were compared with earlier experiments by other workers and with existing models, with obvious differences in the prediction of the transition boundaries. A set of new models and correlations were developed, based on the new data for boiling R134a presented in this thesis, to predict the effect of tube diameter and fluid properties on the transition boundaries. Some also agreed with the limited data available from earlier studies for adiabatic air-water flow in small to normal size tubes.

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Nygaard, Thor Isak. "Two phase swirling flow in a cylindrical reactor." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/10192.

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Wartell, Jason David. "Moisture fraction measurement for two-phase mist flow." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/16876.

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Wälchli, Severin. "Two-phase flow characteristics in gas-liquid microreactors /." Zürich, 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16116.

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Gustafsson, Gabriella. "Multiphase Motion Estimation in a Two Phase Flow." Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5424.

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<p>To improve the control of a steel casting process ABB has developed an Electro Magnetic Brake (EMBR). This product is designed to improve steel quality, i.e. reduce non-metallic inclusions and blisters as well as risk of surface cracks. There is a demand of increasing the steel quality and in order to optimize the steel casting, simulations and experiments play an important role in achieving this. An advanced CFD simulation model has been created to carry out this task.</p><p>The validation of the simulation model is performed on a water model that has been built for this purpose. This water model also makes experiments possible. One step to the simulation model is to measure the velocity and motion pattern of the seeding particles and the air bubbles in the water model to see if it corresponds to the simulation results. </p><p>Since the water is transparent, seeding particles have been added to the liquid in order to observe the motion of the water. They have the same density as water. Hence the particles will follow the ﬂow accurately. The motions of the air bubbles that are added into the water model need also to be observed since they inﬂuence the ﬂow pattern.</p><p>An algorithm - ”Transparent motions” - is thoroughly inspected and implemented. ”Transparent motions” was originally designed to post process x-ray images. However in this thesis, it is investigated whether the algorithm might be applicable to the water model and the image sequences containing seeding particles and air bubbles that are going to be used for motion estimation.</p><p>The result show satisfying results for image sequences of particles only, however with a camera with a faster sampling interval, these results would improve. For image sequences with both bubbles and particles no results have been achieved. </p>

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Vist, Sivert. "Two-phase Flow Distribution in Heat Exchanger Manifolds." Doctoral thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-199.

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<p>The current study has investigated two-phase refrigerant flow distribution in heat exchange manifolds. Experimental data have been acquired in a heat exchanger test rig specially made for measurement of mass flow rate and gas and liquid distribution in the manifolds of compact heat exchangers. Twelve different manifold designs were used in the experiments, and CO<sup>2</sup> and HFC-134a were used as refrigerants. </p>

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Lundberg, Matthew James. "Two-phase reactive flow within variable aperture fractures." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p1427766.

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