Дисертації з теми "Two-phase flow modeling"
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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.
Повний текст джерелаSankaran, Vaidyanathan. "Sub-grid Combustion Modeling for Compressible Two-Phase Flows." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5274.
Повний текст джерелаAl-sarraf, Hayder Hasan Jaafar. "Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503935509157319.
Повний текст джерелаThiele, Roman. "Modeling of Direct Contact Condensation With OpenFOAM." Thesis, KTH, Reaktorteknologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-49825.
Повний текст джерелаXu, Wenyue. "Towards numerical modeling of two-phase flow in seafloor hydrothermal systems." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/26014.
Повний текст джерелаOmurlu, Cigdem. "Mathematical Modeling Of Horizontal Two-phase Flow Through Fully Eccentric Annuli." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607243/index.pdf.
Повний текст джерелаs pressure loss estimations are within ±
30% for two different annular flow geometries.
Biswas, Souvik. "Direct numerical simulation and two-fluid modeling of multi-phase bubbly flows." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-050307-224407/.
Повний текст джерелаKeywords: Multiphase flow; Two-fluid modeling; Direct numerical simulation; Two fluid modeling. Includes bibliographical references (leaves 116-119).
Rochette, Bastien. "Modeling and simulation of two-phase flow turbulent combustion in aeronautical engines." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0059.
Повний текст джерелаNowadays, more than 80% of the energy consumed on Earth is produced by burning fossil fuels. Alternative solutions to combustion are being developed but the specific constraints related to air transport do not make it possible to currently power engines without introducing a technological breakthrough. These findings explain the research activity to improve the knowledge and the control of combustion processes to design cleaner, and more efficient aeronautical engines. In this framework, Large Eddy Simulations (LES) have become a powerful tool to better understand combustion processes and pollutant emissions. This PhD thesis is part of this context and focuses on the models and numerical strategies to simulate with more accuracy turbulent gaseous and two-phase reacting flows in the combustion chamber of aeronautical engines. First, a generic and self-adapting method for flame front detection and thickening has been developed for the TFLES model, and validated on several academic configurations of increasing complexity. This generic approach is then evaluated in the LES of a laboratory-scale burner and compared to the classical thickening method. Results show a more accurate thickening in post-flame regions. Second, from the analysis of 1-D homogeneous laminar spray flames where the dispersed phase has a relative velocity compared to the carrier phase, two analytical formulations for the spray flame propagation speed have been proposed and validated. The agreement between the overall trend of both the measured/estimated spray flame speeds demonstrates that the model and its parameters correctly take into account the main physical mechanisms controlling laminar spray flames. Finally, the state-of-the-art TFLES models were tested on complex turbulent gaseous and two-phase reacting configurations. The pros and cons of these models were investigated to contribute to the understanding of the mechanisms related to turbulent combustion, and to propose a LES modeling strategy to improve the fidelity of reactive simulations
Lewis, Kayla Christine. "An approach to modeling two-phase flow of seawater near an igneous dike." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/25709.
Повний текст джерелаShao, Zhiyu S. "TWO-DIMENSIONAL HYDRODYNAMIC MODELING OF TWO-PHASE FLOW FOR UNDERSTANDING GEYSER PHENOMENA IN URBAN STORMWATER SYSTEM." UKnowledge, 2013. http://uknowledge.uky.edu/ce_etds/5.
Повний текст джерелаFicicilar, Berker. "Electrocatalyst Development And Modeling Of Nonisothermal Two-phase Flow For Pem Fuel Cells." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613276/index.pdf.
Повний текст джерелаMiller, Ryan Michael. "Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4864.
Повний текст джерелаCollin, Félix. "Modeling and numerical simulations of two-phase ignition in gas turbine." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0053.
Повний текст джерелаIn order to meet the new international environmental regulations while maintaining a strong economic competitiveness, innovative technologies of aeronautical combustion chambers are developed. These technologies must guarantee fast relight in case of extinction, which is one of the most critical and complex aspects of engine design. Control of this phase involves a thorough understanding of the physical phenomena involved. In this thesis the full two-phase ignition sequence of an aeronautical engine has been studied, from the breakdown of the spark plug to thepropagation of the flame in the complete engine. For this purpose, Large-Eddy Simulations (LES) using a detailed description of the liquid phase (Euler-Lagrange formalism) and of the combustion process (Analytically Reduced Chemistry) were performed. The results also led to the development of a simplified model for the prediction of ignition probability map, which is particularly useful for the design of combustion chambers
Clark, Randy Raymond. "Modeling Two-Phase Flow in the Downcomer of a Once-Through Steam Generator using RELAP5/MOD2." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76861.
Повний текст джерелаMaster of Science
Studley, Allison F. "Numerical Modeling of Air-Water Flows in Bubble Columns and Airlift Reactors." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/36380.
Повний текст джерелаMaster of Science
Magnini, Mirco <1982>. "CFD modeling of two-phase boiling flows in the slug flow regime with an interface capturing technique." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4437/1/Magnini_Mirco_tesi.pdf.
Повний текст джерелаQuesta tesi si è posta l'obiettivo di migliorare il codice commerciale CFD Ansys Fluent, per ottenere un solutore in grado di compiere simulazioni accurate di flussi in ebollizione nel regime slug flow. Un codice numerico affidabile permette una miglior comprensione della dinamica della bolla causata dall'evaporazione, rendendo possibile la stima dello scambio termico alla parete. Per limitare il costo computazionale delle simulazioni, il problema è modellato con una formulazione assialsimmetrica. Le fasi liquido e vapore sono incomprimibili ed in moto laminare. Attraverso un approccio di tipo single fluid, le equazioni che governano il moto sono scritte come per un flusso a fase singola, tuttavia discontinuità ed effetti di interfaccia vanno introdotti e discretizzati propriamente. Fluent dispone di una tecnica di tipo Volume-of-Fluid per l'avvezione dell'interfaccia e per mappare le discontinue proprietà del fluido su tutto il dominio. Nello slug flow gli effetti di interfaccia sono dominanti, di conseguenza l'accuratezza con cui essi sono calcolati è fondamentale per la veridicità del solutore. A tale scopo, sono state introdotte nel codice numerico delle funzioni esterne, sviluppate appositamente per il calcolo della tensione superficiale e dello scambio di massa ed energia all'interfaccia come conseguenza dell'evaporazione. Le migliori prestazioni del codice modificato rispetto a quello originale sono dimostrate attraverso numerosi casi test. Per provare la validità del nuovo codice numerico nella riproduzione di reali configurazioni di flusso, sono stati simulati diversi flussi adiabatici ed il confronto con i risultati sperimentali è molto positivo. La simulazione dell'evaporazione di una bolla singola evidenzia che la convezione transitoria nel liquido, successivamente al passaggio della bolla, ha un effetto dominante sul coefficiente di scambio termico globale. La simulazione di bolle multiple che evaporano in sequenza mostra che la loro influenza reciproca migliora notevolmente il coefficiente di scambio, fino a due volte il valore a fase singola.
Magnini, Mirco <1982>. "CFD modeling of two-phase boiling flows in the slug flow regime with an interface capturing technique." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4437/.
Повний текст джерелаQuesta tesi si è posta l'obiettivo di migliorare il codice commerciale CFD Ansys Fluent, per ottenere un solutore in grado di compiere simulazioni accurate di flussi in ebollizione nel regime slug flow. Un codice numerico affidabile permette una miglior comprensione della dinamica della bolla causata dall'evaporazione, rendendo possibile la stima dello scambio termico alla parete. Per limitare il costo computazionale delle simulazioni, il problema è modellato con una formulazione assialsimmetrica. Le fasi liquido e vapore sono incomprimibili ed in moto laminare. Attraverso un approccio di tipo single fluid, le equazioni che governano il moto sono scritte come per un flusso a fase singola, tuttavia discontinuità ed effetti di interfaccia vanno introdotti e discretizzati propriamente. Fluent dispone di una tecnica di tipo Volume-of-Fluid per l'avvezione dell'interfaccia e per mappare le discontinue proprietà del fluido su tutto il dominio. Nello slug flow gli effetti di interfaccia sono dominanti, di conseguenza l'accuratezza con cui essi sono calcolati è fondamentale per la veridicità del solutore. A tale scopo, sono state introdotte nel codice numerico delle funzioni esterne, sviluppate appositamente per il calcolo della tensione superficiale e dello scambio di massa ed energia all'interfaccia come conseguenza dell'evaporazione. Le migliori prestazioni del codice modificato rispetto a quello originale sono dimostrate attraverso numerosi casi test. Per provare la validità del nuovo codice numerico nella riproduzione di reali configurazioni di flusso, sono stati simulati diversi flussi adiabatici ed il confronto con i risultati sperimentali è molto positivo. La simulazione dell'evaporazione di una bolla singola evidenzia che la convezione transitoria nel liquido, successivamente al passaggio della bolla, ha un effetto dominante sul coefficiente di scambio termico globale. La simulazione di bolle multiple che evaporano in sequenza mostra che la loro influenza reciproca migliora notevolmente il coefficiente di scambio, fino a due volte il valore a fase singola.
Puig, Montellà Eduard. "Modeling capillarity and two-phase flow in granular media: from porescale to network scale." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667809.
Повний текст джерелаPer tal d’estudiar els fluxos multifàsics presents a molts processos naturals i industrials és indispensable entendre les propietats físiques dels sistemes multifàsics a escala microscòpica. La morfologia dels fluids i les forces capil·lars s’investiguen a l’escala del porus mitjançant el ”multicomponent Shan-Chen lattice Boltzmann method (LBM)”. La precisió del model numèric ha estat contrastada amb solucions teòriques. Els resultats numèrics s’han estès a microestructures líquides complexes més enllà del règim pendular. El LBM ha estat emprat per simular fluxos multifàsics a través de medis porosos sota condicions quasi-estàtiques de drenatge. Les simulacions dutes a terme mitjançant el LBM proporcionen una descripció excel·lent del moviment de la interfície entre fluids a través de les partícules sòlides. Durant el drenatge, les simulacions numèriques són capaces de reproduir l’efecte del fluid atrapat dins el medi granular en forma de ponts o estructures líquides complexes. Malauradament, aquestes simulacions requereixen un temps de computació molt elevat. Per tal d’optimitzar els recursos de computació, proposem un model 2D (model Throat-Network) basat en solucions analítiques que permet reproduir fluxos multifàsics a través d’un conjunt de discs amb un temps de computació molt reduït. Per tant, aquest mètode és una alternativa que pot substituir les simulacions LBM quan els recursos de computació són escassos. El model Throat-Network destaca la importància de tractar el problema a l’escala de la gola del porus per tal d’obtenir les relacions pressió capil·lar - volum locals. Aquest enfocament és un punt de partida pel model híbrid que es presenta per resoldre els problemes en 3D. El model híbrid combina l’eficàcia del model ”Pore-Network” i la precisió del LBM a l’escala del porus. El model híbrid es basa en la descomposició d’una mostra granular en subdominis més petits, els quals corresponen a les goles dels porus (la gola dels porus és l’espai que connecta dos porus adjacents). Les simulacions LBM s’executen per a cada un dels subdominis per tal de determinar les propietats hidroestàtiques més rellevants (pressió capil·lar d’entrada, la corba de pressió capil·lar - grau de saturació i la morfologia líquida per cada una de les goles del porus). Malgrat la reducció significativa en el cost computacional del model híbrid, els temps de càlcul no són menyspreables i poc realistes per mostres granulars de grans dimensions. Les aproximacions donades pels mètodes de l’”Incircle” i el MS-P, que permeten estimar les propietats hidroestàtiques, han estat contrastades amb els resultats obtinguts amb LBM i el model híbrid.
Les simulations numériques à l’échelle du pore sont fréquemment utilisées pour étudier le comportement des écoulements multiphasiques largement rencont des structures liquides et l’actiorés dans phénomènes naturels et applications industrielles. Dans ce travail, la morphologien capillaire sont examinées à l’échelle des pores par la méthode de Boltzmann sur réseau (LBM) à plusieurs composants selon le modèle de Shan-Chen. Les résultats numériques obtenus sont en bon accord avec les solutions théoriques. Les simulations numériques sont étendues à microstructures complexes au-delà du régime pendulaire. La LBM a été utilisée pour modéliser l’écoulement multiphasique à travers un milieu poreux idéalisé dans des conditions de drainage primaire quasi-statique. Les simulations LBM ont fourni une excellente description du déplacement de l’interface fluide-fluide à travers les grains. Pendant le drainage, les simulations LBM sont capables de reproduire la déconnexion d’une phase dans le milieu granulaire sous la forme de ponts pendulaires ou structures liquides complexes. Malheureusement, le temps de calcul nécessaire pour ce type de simulations est assez élevé. Afin d’optimiser les ressources de calcul, nous présentons un modèle 2D (modèle Throat-Network) basé sur des solutions analytiques pour décrire l’écoulement biphasique à travers un ensemble de disques dans un temps de calcul très réduit, donc le modèle 2D est susceptible de remplacer les simulations LBM lorsque les ressources de calcul sont limitées. L’approche souligne l’importance de simuler le problème a l’échelle de la gorge du pore pour obtenir les relations volume - pression capillaire locales. Le modèle Throat-Network est un point de départ pour le modèle hybride proposé pour résoudre les problèmes en 3D. Le modèle hybride combine l’efficacité de l’approche réseau de pores et la précision du LBM à l’échelle des pores. Le modèle hybride est basé sur la décomposition de l’échantillon en petits sous-domaines, dans lesquels des simulations LBM sont effectuées pour déterminer les propriétés hydrostatiques principales (pression capillaire d’entrée, courbe de drainage primaire et morphologie du liquide pour chaque gorge du pore). Malgré la réduction significative des temps de calcul obtenus avec le modèle hybride, le temps n’est pas négligeable et les modélisations numériques d’échantillons de grandes tailles ne sont pas réalistes. Les approximations données par les méthodes Incircle et MS-P, qui prédisent les propriétés hydrostatiques, sont comparées à celles de LBM et du modèle hybride.
Yang, Weiwei. "Mathematical modeling of two-phase mass transport in liquid-feed direct methanol fuel cells /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?MECH%202009%20YANG.
Повний текст джерелаGhrist, Melissa Renee. "Zero gravity two-phase flow regime transition modeling compared with data and relap5-3d predictions." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2353.
Повний текст джерелаPuig, Montellà Eduard. "Modeling capillarity and two-phase flow in granular media : from pore-scale to network scale." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI046/document.
Повний текст джерелаNumerical simulations at the pore scale are a way to study the behavior of multiphase flows encountered in many natural processes and industrial applications. In this work, liquid morphology and capillary action are examined at the pore-scale by means of the multicomponent Shan-Chen lattice Boltzmann method (LBM). The accuracy of the numerical model is first contrasted with theoretical solutions. The numerical results are extended to complex microstructures beyond the pendular regime.The LBM has been employed to simulate multiphase flow through idealized granular porous media under quasi-static primary drainage conditions. LBM simulations provide an excellent description of the fluid-fluid interface displacement through the grains. Additionally, the receding phase trapped in the granular media in form of pendular bridges or liquid clusters is well captured. Unfortunately, such simulations require a significant computation time. A 2D model (Throat-Network model) based on analytical solutions is proposed to mimic the multiphase flow with very reduced computation cost, therefore, suitable to replace LBM simulations when the computation resources are limited. The approach emphasizes the importance of simulating at the throat scale rather than the pore body scale in order to obtain the local capillary pressure - liquid content relationships. The Throat-Network model is a starting point for the a hybrid model proposed to solve 3D problems. The hybrid model combines the efficiency of the pore-network approach and the accuracy of the LBM at the pore scale to optimize the computational resources. The hybrid model is based on the decomposition of the granular assembly into small subsets, in which LBM simulations are performed to determine the main hydrostatic properties (entry capillary pressure, capillary pressure - liquid content relationship and liquid morphology for each pore throat). Despite the reduction of computation time, it is still not negligible and not affordable for large granular packings. Approximations by the Incircle and the MS-P method, which predict hydrostatic properties, are contrasted with the results provided by LBM and the hybrid model. Relatively accurate predictions are given by the approximations
Kamboj, Brij Kumar. "Modeling of once-through steam generator thermal-hydraulics during a loss of coolant accident." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16660.
Повний текст джерелаAshari, Alireza. "Dual-Scale Modeling of Two-Phase Fluid Transport in Fibrous Porous Media." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2326.
Повний текст джерелаBurkholder, Michael B. "Nonlinear Analysis, Control, and Modeling of the Two-Phase Flow Dynamics in Polymer Electrolyte Fuel Cells." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/618.
Повний текст джерелаKourakos, Vasilios. "Experimental study and modeling of single- and two-phase flow in singular geometries and safety relief valves." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209827.
Повний текст джерелаThe flow of a mixture of two fluids in pipes can be frequently encountered in nuclear, chemical or mechanical engineering, where gas-liquid eactors, boilers, condensers, evaporators and combustion systems can be used. The presence of section changes or more generally geometrical singularities in pipes may affect significantly the behavior of twophase flow and subsequently the resulting pressure drop and mass flow rate. Therefore, it is an important subject of investigation in particular when the application concerns industrial safety valves.
This thesis is intended to provide a thorough research on two-phase (air-water) flow phenomena under various circumstances. The project is split in the following steps. At first, experiments are carried out in simple geometries such as smooth and sudden divergence and convergence singularities. Two experimental facilities are built; one in smaller scale in von Karman Institute and one in larger scale in CETIM. During the first part of the study, relatively simple geometrical discontinuities are investigated. The characterization and modeling of contraction and expansion nozzles (sudden and smooth change of section) is carried out. The pressure evolution is measured and pressure drop correlations are deduced. Flow visualization is also performed with a high-speed camera; the different flow patterns are identified and flow regime maps are established for a specific configuration.
A dual optical probe is used to determine the void fraction, bubble size and velocity upstream and downstream the singularities.
In the second part of the project, a more complex device, i.e. a Safety Relief Valve (SRV), mainly used in nuclear and chemistry industry, is thoroughly studied. A transparent model of a specific type of safety valve (1 1/2" G 3") is built and investigated in terms of pressure evolution. Additionally, flow rate measurements for several volumetric qualities and valve openings are carried out for air, water and two-phase mixtures. Full optical access allowed identification of the structure of the flow. The results are compared with measurements performed at the original industrial valve. Flowforce analysis is performed revealing that compressible and incompressible flowforces in SRV are inversed above a certain value of valve lift. This value varies with critical pressure ratio, therefore is directly linked to the position at which chocked flow occurs during air valve operation. In two-phase flow, for volumetric quality of air=20%, pure compressible flow behavior, in terms of flowforce, is remarked at full lift. Numerical simulations with commercial CFD code are carried out for air and water in axisymmetric 2D model of the valve in order to verify experimental findings.
The subject of modeling the discharge through a throttling device in two-phase flow is an important industrial problem. The proper design and sizing of this apparatus is a crucial issue which would prevent its wrong function or accidental operation failure that could cause a hazardous situation. So far reliability of existing models predicting the pressure drop and flow discharge in two-phase flow through the valve for various flow conditions is questionable. Nowadays, a common practice is widely adopted (standard ISO 4126-10 (2010), API RP 520 (2000)); the Homogeneous Equilibrium Method with the so-called !-method, although it still needs further validation. Additionally, based on !-methodology, Homogeneous Non-Equilibrium model has been proposed by Diener and Schmidt (2004) (HNE-DS), introducing a boiling delay coefficient. The accuracy of the aforementioned models is checked against experimental data both for transparent model and industrial SRV. The HNE-DS methodology is proved to be the most precise among the others. Finally, after application of HNE-DS method for air-water flow with cavitation, it is concluded that the behavior of flashing liquid is simulated in such case. Hence, for the specific tested conditions, this type of flow can be modeled with modified method of Diener and Schmidt (CF-HNE-DS) although further validation of this observation is required.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Blake, Kevin. "Experimental Characterization and Modeling of Wettability in Two Phase Oil/Water Flow in the Annular Flume Apparatus." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1547060617833221.
Повний текст джерелаLaw, Deify. "Computational Modeling and Simulations of Hydrodynamics for Air-Water External Loop Airlift Reactors." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/27991.
Повний текст джерелаPh. D.
Deza, Grados Mirka. "Modeling the Hydrodynamics of a Fluidized Bed." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/37554.
Повний текст джерелаPh. D.
Kanholy, Santhip Krishnan. "Eulerian-Eulerian Modeling of Fluidized Beds." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/50626.
Повний текст джерелаPh. D.
Lewis, Kayla Christine. "Numerical Modeling of Two-Phase Flow in the Sodium Chloride-Water System with Applications to Seafloor Hydrothermal Systems." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19810.
Повний текст джерелаZhou, Xinquan. "Measurement and Modeling of the Liquid-phase Turbulence in Adiabatic Air-water Two-phase Flows with a Wide Range of Void Fractions." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406210359.
Повний текст джерелаOrtiz-Arroyo, Arturo. "Contribution to the modeling of packed bed reactors under plugging conditions in single and two phase trickle flow." Doctoral thesis, Québec : Université Laval, 2004. http://www.theses.ulaval.ca/2004/21789/21789.pdf.
Повний текст джерелаShaik, Abdul Qaiyum. "Numerical modeling of two-phase flashing propellant flow inside the twin-orifice system of pressurized metered dose inhalers." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6161.
Повний текст джерелаByers, Ashley. "Numerical Modeling of Capillary Flow in a Novel Micropillar Geometry for Applications in Passive Two-Phase Cooling Systems." Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10000329.
Повний текст джерелаMicrostructures have become an increasingly popular method for two phase heat removal in electronics. Maximizing capillary pressure and thermal conductivity are the most direct methods for increasing heat removal in capillary-driven, two-phase cooling systems. It is well known that closely packed wicking structures produce a higher capillary pressure. However, this adversely affects the permeability of the fluid inhibiting its ability to flow, thus reducing heat removal capability. This research aims to address this issue. A numerical model is implemented with a novel micropillar structure to increase capillary pressure while maintaining necessary permeability. These novel micropillar structures have a larger spacing at the base of the micropillar to provide a higher liquid permeability and mushroom-like structure on the top surface of the micropillars with a smaller spacing to provide a greater capillary pressure. The results indicate that the liquid column rise of the mushroom-like structures is 6 times higher than standard micropillar arrays for a contact angle of 50°.
Alp, Doruk Ayala Luis F. "Numerical modeling of natural gas two-phase flow split at branching T-junctions with closed-loop network applications." [University Park, Pa.] : Pennsylvania State University, 2008. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-4688/index.html.
Повний текст джерелаGustavsson, Katarina. "Mathematical and Numerical Modeling of 1-D and 2-D Consolidation." Doctoral thesis, KTH, Numerical Analysis and Computer Science, NADA, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3497.
Повний текст джерелаA mathematical model for a consolidation process of a highlyconcentrated, flocculated suspension is developed.Thesuspension is treated as a mixture of a fluid and solidparticles by an Eulerian two-phase fluid model.W e characterizethe suspension by constitutive relations correlating thestresses, interaction forces, and inter-particle forces toconcentration and velocity gradients.This results in threeempirically determined material functions: a hystereticpermeability, a non-Newtonian viscosity and a non-reversibleparticle interaction pressure.P arameters in the models arefitted to experimental data.
A simulation program using finite difference methods both intime and space is applied to one and two dimensional testcases.Numer ical experiments are performed to study the effectof different viscosity and permeability models. The effect ofshear on consolidation rate is studied and it is significantwhen the permeability hysteresis model is employed.
Wolff, Markus [Verfasser], and Rainer [Akademischer Betreuer] Helmig. "Multi-scale modeling of two-phase flow in porous media including capillary pressure effects / Markus Wolff. Betreuer: Rainer Helmig." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2013. http://d-nb.info/1044294337/34.
Повний текст джерелаLaín, Beatove Santiago [Verfasser]. "On modeling and numerical computation of industrial disperse two-phase flow with the Euler-Lagrange approach / Santiago Laín Beatove." Aachen : Shaker, 2010. http://d-nb.info/1120863953/34.
Повний текст джерелаDessirier, Benoît. "Numerical modeling of groundwater and air flow between compacted bentonite and fractured crystalline rock." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-124428.
Повний текст джерелаAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 4: Manuscript.
MAMELI, Mauro. "Pulsating heat pipes. Numerical Modelling and Experimental Assessment." Doctoral thesis, Università degli studi di Bergamo, 2012. http://hdl.handle.net/10446/222122.
Повний текст джерелаMameli, Mauro. "Pulsating heat pipes. Numerical Modelling and Experimental Assessment." Doctoral thesis, Università degli studi di Bergamo, 2012. http://hdl.handle.net/10446/26720.
Повний текст джерелаHan, Liang. "Exploring two-phase hydrothermal circulation at a seafloor pressure of 25 MPa: Application for EPR 9°50′N." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/45440.
Повний текст джерелаMaster of Science
Khallahle, Jack Buckhill. "Numerical Simulation of Flow Parameters in Stratified Gas-Liquid Flow in a Horizontal Pipe." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29931.
Повний текст джерелаMaggiolo, Dario. "Numerical modeling and fluid-dynamic optimisation of fuel cells and flow batteries systems." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3424775.
Повний текст джерелаAl giorno d'oggi, la sfida energetica è una delle più importanti spinte alla ricerca scientifica. Le strategie energetiche future includono vie alternative ed efficienti per stoccare e convertire l'energia su richiesta. In questa prospettiva entusiasmante, le celle a combustibile e le batterie a flusso svolgono un ruolo chiave, le prime nella conversione dell'energia in propulsione, le seconde nello stoccaggio dei surplus derivanti da energia rinnovabile. Tuttavia, rimangono ancora da superare alcuni importanti aspetti tecnologici, come ad esempio le limitate prestazioni di picco spesso causate da una scarsa efficienza fluido-meccanica. L'obiettivo principale della presente tesi è l'ottimizzazione fluidodinamica delle celle a combustibile e delle batterie a flusso. A tal fine, la ricerca si focalizza sullo studio dei flussi bifase liquido-vapore e delle dinamiche di dispersione in mezzi porosi, mediante modelli numerici Lattice-Boltzmann, al fine di studiare gli effetti dei fenomeni microscopici sulle caratteristiche macroscopiche di entrambe le tecnologie. I risultati di questo studio forniscono nuove interpretazioni nella comprensione dei comportamenti fisici fondamentali nelle celle a combustibile e nelle batterie di flusso, ed offrono linee guida per una buona e innovativa pratica di progettazione.
Lema, Rodríguez Marcos. "Multiphase fluid hammer: modeling, experiments and simulations." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209540.
Повний текст джерелаThe motivation of this research work comes from the liquid propulsion systems used in spacecrafts, which can undergo fluid hammer effects threatening the system integrity. Fluid hammer can be particularly adverse during the priming phase, which involves the fast opening of an isolation valve to fill the system with liquid propellant. Due to the initial vacuum conditions in the pipeline system, the water hammer taking place during priming may involve multiphase phenomena, such as cavitation and desorption of a non-
condensable gas, which may affect the pressure surges produced in the lines. Even though this flow behavior is known, only few studies model the spacecraft hardware configuration, and a proper characterization of the two-phase flow is still missing. The creation of a reliable database and the physical understanding of the water hammer behavior in propulsion systems are mandatory to improve the physical models implemented in the numerical codes used to simulate this flow configuration.
For that purpose, an experimental facility modeling a spacecraft propulsion system has been designed, in which the physical phenomena taking place during priming are generated under controlled conditions in the laboratory using inert fluids. An extended experimental campaign was performed on the installation, aiming at analyzing the effect of various working parameters on the fluid hammer behavior, such as the initial pressure in the line, liquid saturation with the pressurant gas, liquid properties and pipe configuration. The influence of the desorbed gas during water hammer occurrence is found to have a great importance on the whole process, due to the added compressibility and lower speed of sound by an increasing amount of non-condensable gas in the liquid + gas mixture. This results in lower pressure levels and faster pressure peaks attenuation, compared to fluids without desorption. The two-phase flow was characterized by means of flow visualization of the liquid front at the location where the fluid hammer is generated. The front arrival was found to be preceded by a foamy mixture of liquid, vapor and non-condensable gas, and the pressure wave reflected at the tank may induce the liquid column separation at the bottom end. While column separation takes place, the successive pressure peaks are generated by the impact of the column back against the bottom end.
The resulting experimental database is then confronted to the predictions of the 1D numerical code EcosimPro/ESPSS used to assess the propulsion system designs. Simulations are performed with the flow configuration described before, modeling the experimental facility. The comparison of the numerical results against the experimental data shows that aspects such as speed of sound computation with a dissolved gas and friction modeling need to be improved.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Yang, Songzhi. "Modeling of Diesel injection in subcritical and supercritical conditions." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC045/document.
Повний текст джерелаTo satisfy latest stringent emission regulations, important progress is still be expected from internal combustion engines. In addition, improving engine efficiency to reduce the emission and fuel consumption has become more essential than before. But many complex phenomena remain poorly understood in this field, such as the fuel injection process. Numerous software programs for computational fluid dynamics (CFD) considering phase change (such as cavitation) and injection modelling, have been developed and used successfully in the injection process. Nevertheless, there are few CFD codes able to simulate correctly transcritical conditions starting from a subcritical fuel temperature condition towards a supercritical mixture in the combustion chamber. Indeed, most of the existing models can simulate either single-phase flows possibly in supercritical condition or two-phase flows in subcritical condition; lacking therefore, a comprehensive model which can deal with transcritical condition including possible phase transition from subcritical to supercritical regimes, or from single-phase to two-phase flows, dynamically. This thesis aims at dealing with this challenge. For that, real fluid compressible two-phase flow models based on Eulerian-Eulerian approach with the consideration of phase equilibrium have been developed and discussed in the present work. More precisely, a fully compressible 6-equation model including liquid and gas phases balance equations solved separately; and a 4-equation model which solves the liquid and gas balance equations in mechanical and thermal equilibrium, are proposed in this manuscript. The Peng-Robinson equation of state (EoS) is selected to close both systems and to deal with the eventual phase change or phase transition. Particularly, a phase equilibrium solver has been developed and validated. Then, a series of 1D academic tests involving the evaporation and condensation phenomena performed under subcritical and supercritical conditions have been simulated and compared with available literature data and analytical results. Then the fully compressible two-phase flow models (6-Equation and 4-Equation systems) have been employed to simulate the cavitation phenomena in a real size 3D nozzle to investigate the effect of dissolved N2 on the inception and developing of cavitation. The good agreement with experimental data proves the solver can handle the complex phase change behavior in subcritical condition. Finally, the capability of the solver in dealing with the transcritical injection at high pressure and temperature conditions has been further validated through the successful modelling of the engine combustion network (ECN) Spray A injector
Colombano, Stéfan. "Improvement of the recovery of heavy chlorinated organic compounds in saturated porous media by thermal and chemical enhancements : experimental and two-phase flow modeling approaches." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2032.
Повний текст джерелаGroundwater pollution by chlorinated organic compounds is a major problem. Actually, these particularly toxic pollutants, permanently degrade soil and groundwater quality. Their dispersion (by solubilization and volatilization) from the pollution source zone can generate large contaminants plumes.Chlorinated organic compounds are recovered as pure product (Dense Non-Aqueous Phase Liquids-DNAPL) mainly using pump/treat technologies. However, these technologies are time-consuming and do not recover the pure product in an efficient way. A significant amount of DNAPL remains trapped in soil as residual saturation (Srn). The objective of this PhD project was to enhance DNAPL recovery rate and yield using chemical and thermal enhancements during the pumping process. Temperature increases aimed to reduce the viscosity of DNAPL (and therefore to increase its mobility) while the addition of surfactant aimed to reduce the capillary forces that trap the DNAPL. Experiments at the laboratory scale (based on monitoring of permittivities, electrical resistivities and optical densities) and two-phase flow modeling were performed to quantify the effects of these enhancements. Heating the DNAPL up to 50 °C (to avoid volatilization) decreases the viscosity by a factor of two. The addition of surfactant, Sodium Dodecyl Benzene Sulfonate-SDBS, at its Critical Micelle Concentration (to prevent DNAPL solubilization) decreases interfacial tensions by a factor of 12. Drainage-imbibition experiments were carried out in 1D cells to obtain the retention curves of the two-phase system (capillary pressure as a function of water saturation). The decreases of Srn obtained with SDBS were 28% for 0.5 mm glass beads (GB) diameter and 46% for 0.1 mm GB. We reported no significant improvement in the remediation yield with thermal enhancement. The curves were fitted with the van Genuchten – Mualem model to generate data for modeling.Drainage-imbibition experiments were carried out in 1D columns to characterize two-phase flow (and in particular the displacement of the DNAPL-water interface according to the pressures applied). The two-phase flow model used a pressure-pressure formulation (using COMSOL Multiphysics®). The modeling of recovered volumes and the displacement of the interface agreed with the experimental results. The remediation yields with chemical and thermal enhancements were of the same order of magnitude as those reported in 1D cells. For 2D tank experiments, pumping was performed at different flow rates with 0.5 mm and 0.1 mm GB. The experiments were also performed with and without enhancement. Models were compared with image interpretation (based on the optical density calibration). Comparing experimental and modeled values shows that the model fitted well with the experiments. The VDNAPL, chemical/VDNAPL, reference ratios were for low and high flow rates on average respectively 2.90 and 1.40 for 0.5 mm GB and 1.37 and 1.18 for 0.1 mm GB. Thermal enhancement had no beneficial effect on DNAPL recovery rate or yield.Indirect measurements of water saturations (Sw) for 1D or 2D experiments yielded the following results: i. the measured permittivities were very similar to the values modeled with the CRIM model; ii. modeling of electrical resistivities with Archie's Law was less accurate; iii. optical densities allow accurate Sw estimation. At field scale, the combination of monitoring both electrical resistivities (which provide a global picture) and permittivities (which provide precise but spatially limited data), is expected to provide Srn data
Danés, Leandro Henschel 1986. "Mediação de parâmetro de escoamento bifásico gás-líquido utiizando sensores de impedância." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263023.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Uma mistura de gás e liquido escoando em um tubo em diferentes faixas de vazões se comporta como diferentes padrões de escoamento, em que interações cinemáticas e dinâmicas especificas de cada padrão, ocorrem entre gás e liquido. A estimação de dados sobre a velocidade media de deslocamento e a vazão de ambas as fases depende da aplicação de estratégias estatísticas de e de modelos de escoamento para calcular estas informações. Neste trabalho, um sensor de impedância que, se devidamente calibrado, possui sinal proporcional ao nível de liquido na seção transversal do duto, foi utilizado para a obtenção destes dados sendo desenvolvidas técnicas e estratégias para alcançar este objetivo. O estudo foi desenvolvido no regime de escoamento horizontal água-ar nos regimes de bolhas alongadas, estratificado intermitente. Foram utilizadas técnicas para a obtenção da velocidade media de deslocamento do escoamento bifásico a partir de um arranjo de dois sensores de impedância em serie. Foi utilizada a técnica da correlação cruzada e foram elaboradas e apresentadas como opção, uma técnica baseada no calculo numérico e outra na covariância entre os sinais como alternativa. As técnicas foram testadas e comparadas. Foram utilizados modelos de escoamento e levantadas hipóteses para a estimativa das vazões de gás e liquido. Foram realizadas estimativas para o padrão de bolhas alongadas, estratificado e intermitente. Para o regime intermitente, considerado foco do estudo, foram obtidas respectivamente para gás e liquido, margens de erro de 24.4% e 28% considerando um perfil de escoamento constante e margens de 12.5% e 20.5% para um perfil laminar
Abstract: A gas-liquid moisture flowing in a tube at different flow rates , behaves as different flow patterns, which cinematic and dynamic interactions occurs between the gas and liquid phases. The estimation of average displacement rate data and flow data for both phases depends of the application of statistical strategies and floe models for calculating the information. In this work, a impedance sensor which, is correctly calibrated, has a proportional out to the liquid level of the tube cross section, was used for obtaining these data with techniques and strategies developed to achieve this goal. The study was developed for horizontal air-water flow at the bubbles, stratified and slug patterns. It was used techniques for obtaining the average displacement speed of the flow between the two sensors. The cross-correlation technique was used and a numeric calculus based technique and a covariance based technique were elaborated and presented as an option. The techniques were tested and compared. Flow-models were used and hypothesis were take in order to make estimations of gas and liquid flow magnitude. Estimatives were done for the elongated bubbles , stratified and slug patterns. For the slug pattern ,focus of the work, it was obtained respectively for the gas and the liquid phase, error margins of 24,4% and 28% considering a constant flow profile and 12.5% and 20.5% margins considering a laminar flow profile
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
Ozturk, Onur Can. "Contribution expérimentale à l'amélioration des modèles de transition de régime en écoulement diphasique horizontal." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI113.
Повний текст джерелаSeveral horizontal water-air two-phase adiabatic flows (dispersed bubbly flows and intermittent flows)and their axial evolutions have been studied in the METERO experiment which is consisted of ahorizontal circular test section with an internal diameter of 100 mm. Different measurement techniqueshave been improved and utilized to measure the flow characteristics in order to bring a localdescription and axial evolution of the flows. The responsible physical mechanisms of the flow regimesand their transitions, particularly the competition between turbulent force and buoyancy force havebeen explained. The differences between dispersed bubbly flows and intermittent flows have beenhighlighted and the physical process at the origin of these differences has been explained. Two newdimensionless flow regime maps have been proposed: the first one brings an improvement to therepresentation of Taitel & Dukler (1976) and proposes new transition criteria. The second novel maptakes into account the effects of turbulent and buoyancy forces and the void fraction
Printsypar, Galina [Verfasser], and Oleg [Akademischer Betreuer] Iliev. "Mathematical Modeling and Simulation of Two-Phase Flow in Porous Media with Application to the Pressing Section of a Paper Machine / Galina Printsypar. Betreuer: Oleg Iliev." Kaiserslautern : Universitätsbibliothek Kaiserslautern, 2012. http://d-nb.info/1022804308/34.
Повний текст джерела