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Yuan, Ruoyang. "Measurements in swirl-stabilised spray flames at blow-off." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709345.
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Zhang, Fan. "Spray, combustion and emission characteristics of dieseline fuel." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4699/.
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The spray, combustion and emissions characteristics of diesel and gasoline blends (dieseline) were studied. Experimental results showed that the dieseline fuel spray had tip penetration length similar as diesel. With an increase of the gasoline/diesel blending ratio, the fuel droplets size decreased. When operating with dieseline, the engine's PM emissions were much lower than diesel. With advanced injection timing and large amounts of EGR, both the NOx and PM emissions of dieseline combustion were reduced significantly at part loads. Using split injection strategies gave even more flexibility for the control of mixing strength and combustion phasing. However, the power density of dieseline fuelled PPCI operation was limited. A novel concept, Stoichiometric Dual-fuel Compression Ignition (SDCI) was investigated. The diesel and gasoline were blended internally through direct injection and port fuel injection respectively. Stoichiometric condition was maintained through adjusting the EGR ratio, which thus allows for a three-way-catalyst to handle gaseous emissions. Experimental results showed that the SDCI combustion can achieve better thermal efficiency and lower PM emissions than conventional diesel combustion. Overall, the SDCI concept was proved to be a promising technique for optimising a CI engine's efficiency, emissions and noise without compromise of cost and power density.
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Li, Yanfei. "Experimental study on spray and combustion characteristics of diesel-like fuels." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3428/.
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With increasing concern on the dwindling of the fossil fuel reserve and climate change, more and more effort has been focused on seeking green fuel to replace fossil fuel and mitigating the emissions of greenhouse gas (GHG). Biodiesel has attracted much attention for its sustainability, lower emissions of HC, PM and CO, and the diverse feedstock. In this study, diesel/diesel-like fuels were experimentally studied in terms of spray and combustion characteristics.
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Garcia, Pardo Diego. "Piston bowl combustion simulation - From fuel spray calibration to emissions minimization." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203950.
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The current pollution policies in all European and American countries are forcing the industry to movetowards a more efficient and environmentally friendly engines. On the other hand, customers requiremaintaining the power and fuel consumption. Lowering mainly nitrous oxides (NOx) and carbon particles(Soot) is therefore a challenging task with a very strong impact on mainly the automotive andaeronautical market.The purpose of the current work is to research the pollution production of automotive diesel enginesand optimize the fuel injection and piston geometry to lower the emissions. The interaction betweenfuel and air as well as the combustion are the two main physical and chemical processes governing thepollutants formation. Converged-CFD will be the CFD tool employed during the analysis of the previousproblems.The fuel-air interaction is related to jet break up, vaporization and turbulence. The strong dependenceon the surrounding flow field of the previous processes require the equations to be solved numericallywithin a CFD code. The fuel is to be placed in a combustion chamber (piston) where the spray will affectthe surrounding flow field and ultimately the combustion process.In order to accurately represent the nature of the processes, the current work is divided into two mainchapters. Spray modelling and Combustion Modelling. The first will help to accurately model the discretephase (fuel spray) and the vapour entrainment. The second chapter, combustion modelling willretrieve the knowledge gain in the first part to accurately represent the fuel injection in the chamber aswell as the combustion process to ultimately model the pollutants emissions.Finally, a piston bowl optimization will be performed using the previous analysed models and give theindustry a measure of the potential improvement by just adjusting the fuel injection or by modifyingthe piston bowl geometry.
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Patel, Nayan V. "Simulation of Hydrodynamic Fragmentation from a Fundamental and an Engineering Perspective." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16225.
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Liquid fragmentation phenomenon is explored from both a fundamental (fully resolved) and an engineering (modeled) perspective. The dual objectives compliment each other by providing an avenue to gain further understanding into fundamental processes of atomization as well as to use the newly acquired knowledge to address practical concerns. A compressible five-equation interface model based on a Roe-type scheme for the simulation of material boundaries between immiscible fluids with arbitrary equation of state is developed and validated. The detailed simulation model accounts for surface-tension, viscous, and body-force effects, in addition to acoustic and convective transport. The material interfaces are considered as diffused zones and a mixture model is given for this transition region. The simulation methodology combines a high-resolution discontinuity capturing method with a low-dissipation central scheme resulting in a hybrid approach for the solution of time- and space-accurate interface problems. Several multi-dimensional test cases are considered over a wide range of physical situations involving capillary, viscosity, and gravity effects with simultaneous presence of large viscosity and density ratios. The model is shown to accurately capture interface dynamics as well as to deal with dynamic appearance and disappearance of material boundaries.
Simulation of atomization processes and its interaction with the flow field in practical devices is the secondary objective of this study. Three modeling requirements are identified to perform Large-Eddy Simulation (LES) of spray combustion in engineering devices. In concurrence with these requirements, LES of an experimental liquid-fueled Lean Direct Injection (LDI) combustor is performed using a subgrid mixing and combustion model. This approach has no adjustable parameters and the entire flow-path through the inlet swirl vanes is resolved. The inclusion of the atomization aspects within LES eliminates the need to specify dispersed-phase size-velocity correlations at the inflow boundary. Kelvin-Helmholtz (or aerodynamic) breakup model by Reitz is adopted for the combustor simulation. Two simulations (with and without breakup) are performed and compared with measurements of Cai et al. Time-averaged velocity prediction comparison for both gas- and liquid-phase with available data show reasonable agreement. The major impact of breakup is on the fuel evaporation in the vicinity of the injector. Further downstream, a wide range of drop sizes are recovered by the breakup simulation and produces similar spray quality as in the no-breakup case.
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Tabbara, Hani. "Numerical investigations of thermal spray coating processes : combustion, supersonic flow, droplet injection, and substrate impingement phenomena." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/348993/.
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The aim of this thesis is to apply CFD methods to investigate the system characteristics of high speed thermal spray coating processes in order facilitate technological development. Supersonic flow phenomena, combustion, discrete droplet and particle migration with heating, phase change and disintegration, and particle impingement phenomena at the substrate are studied. Each published set of results provide an individual understanding of the underlying physics which control different aspects of thermal spray systems. A wide range of parametric studies have been carried out for HVOF, warm spray, and cold spay systems in order to build a better understanding of process design requirements. These parameters include: nozzle cross-section shape, particle size, processing gas type, nozzle throat diameter, and combustion chamber size. Detailed descriptions of the gas phase characteristics through liquid fuelled HVOF, warm spray, and cold spray systems are built and the interrelations between the gas and powder particle phases are discussed. A further study looks in detail at the disintegration of discrete phase water droplets, providing a new insight to the mechanisms which control droplet disintegration, and serves as a fundamental reference for future developments of liquid feedstock devices. In parallel with these gas-particle-droplet simulations, the impingement of molten and semi-molten powder droplets at the substrate is investigated and the models applied simulate the impingement, spreading and solidification. The results obtained shed light on the break-up phenomena on impact and describe in detail how the solidification process varies with an increasing impact velocity. The results obtained also visually describe the freezing induced break-up phenomenon at the splat periphery.
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Svensson, Kenth Ingemar. "Effects of Fuel Molecular Structure and Composition on Soot Formation in Direct-Injection Spray Flames." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd830.pdf.
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Ong, Jiun Cai. "Development of Lagrangian soot tracking method for the study of soot morphology in diesel spray combustion." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43024/.
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The weakness of a conventional Eulerian soot model in capturing primary soot size and its inability to access individual soot information led to the development of a Lagrangian soot tracking (LST) model as reported in this thesis. The LST model aimed to access the history of individual soot particles and capture the soot concentration and primary soot size distribution in high pressure spray flames, under diesel-like conditions. The model was validated in a constant volume spray combustion chamber by comparing the predicted soot volume fraction (SVF), mean primary soot diameter and primary soot size distribution to the experimental data of n-heptane and n-dodecane spray combustion. The inception, surface growth and oxidation models were adopted and modified from the multistep Moss-Brookes (MB) soot model, which was used in this study as the representative of Eulerian soot model. Parametric studies were carried out to investigate the influence of soot surface ageing and oxidation rates on the overall soot formation. Following the parametric study, the developed LST model which incorporated surface ageing effect and higher oxidation rates was implemented to investigate the effect of ambient oxygen and density on soot morphology in n-heptane spray flame. The LST model was shown to have better primary soot size prediction capability while still maintaining comparable performance in predicting SVF with respect to its Eulerian counterpart. The SVF distributions predicted by the LST model qualitatively correspond to the experimental results despite the peak soot location being predicted further downstream by 30 mm. The primary soot size distribution predicted by the LST model had the same order as the measured primary soot size distribution despite predicting larger soot size. The presence of surface ageing factor had a significant effect on the primary soot size distribution whereas only a slight effect on the SVF profile. A maximum soot size reduction of 48% was obtained when incorporating surface ageing effect. The consideration of surface ageing effect led to smaller primary soot size predicted and better agreement with the measured primary soot size distribution. The peak and mean primary soot sizes increased with increasing ambient density, from 14.8 kg/m3 to 30 kg/m3, at the core of spray jet. Meanwhile, the decrease in oxygen level from 21% to 12% at an ambient density of 14.8 kg/m3 caused a non-monotonic effect on the primary soot sizes at the core of spray jet. Trivial differences were predicted when oxygen level decreased from 21% to 15%. However, a significantly smaller primary soot sizes were predicted when oxygen level decreased further to 12%. In addition to net growth rates, soot cloud span and soot age were also found to play an important role in evolution of primary soot size. An increase in ambient oxygen and density resulted in a more upstream first-soot location. The effect of ambient density on soot age was not significant, whereas a lower oxygen level resulted in a longer soot age. A maximum soot age of 0.50 ms was obtained for both 21% and 15% O2 cases at both density levels. As oxygen level decreased to 12%, the maximum soot age increased to 0.58 ms due to lower combustion temperature. Overall, the LST model was shown to perform better in predicting primary soot size and can access information of individual soot particles which are both shortcomings of the Eulerian method. In addition, the LST model was also demonstrated to be able to predict soot age. Apart from playing a role in determining primary soot size, soot age can also serve as a useful parameter to answer various fundamental questions, such as when and where soot particles grow to a certain size, and help in the understanding of fundamental soot processes. Optimisation of the model and extension of its capability to capture soot aggregate structure, size and fractal dimension will be of interest in the future.
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Wåhlin, Fredrik. "Experimental Investigation of Impinging Diesel Sprays for HCCI Combustion." Doctoral thesis, KTH, Maskinkonstruktion (Avd.), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4276.
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Engine research and development is to a large extent driven by the quest of lowering exhaust emissions and fuel consumption. The combination of low emissions and low fuel consumption is not the simultaneous characteristic of the world’s primary engine concepts, the diesel and the spark-ignited (SI) engine. However, such a concept do exist, it is commonly called Homogeneous Charge Compression Ignition (HCCI). The HCCI combustion concept is when a premixed air and fuel mixture is ignited by the heat of compression. The operation is unthrottled, like the diesel engine, which is advantageous for its efficiency. The premixed air / fuel mixture preclude soot formation, like the SI engine. An exclusive feature of HCCI combustion is extremely low NOX production due to low-temperature combustion. The mixture preparation of the typical gasoline HCCI engine is similar to the SI engine, via port-injection, which results in a well homogenized mixture. Port injection of diesel fuel is however very difficult since the environment is too cold for the fuel to vaporise. A better alternative is therefore direct-injection. However, injection must occur in a way where a homogeneous mixture is formed, while contact of the liquid fuel with cold walls is avoided. There are many approaches to direct-injected mixture formation. This thesis focuses on exploring the concept of impinging sprays; its characteristics and its impact on combustion and emissions. The work comprises unique information regarding impinging sprays, as well as results regarding engine performance. It is concluded that impinging sprays are well suited for early direct-injection.<br>QC 20100824
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Archibald, Reid S. "Characteristics of Combustion Flame Sprayed Nickel Aluminum Using a Coanda Assisted Spray Manipulation Collar for Off-Normal Deposits." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/964.
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A novel flame spray collar called the Coanda Assisted Spray Manipulation collar (CSM) has been tested for use on the Sulzer Metco 5P II combustion flame spray gun. A comparison study of the stock nozzle and the CSM has been performed by evaluating the porosity, surface roughness, microhardness, tensile strength and microscopy of normal and off-normal sprayed NiAl deposits. The use of the CSM collar resulted in the need to position the sprayed coupons closer to the gun, which in turn affected the particle impact energy and particle temperatures of the NiAl powder. For the CSM, porosities had a larger scatterband, surface roughness was comparably the same, microhardness was lower, and tensile strength was higher. The microscopy analysis revealed a greater presence of unmelted particles and steeper intersplat boundaries for the CSM. For both processes, the porosity and surface roughness increased and the microhardness decreased as the spray angle decreased.
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Lebas, Romain. "Modélisation Eulérienne de l'Atomisation Haute Pression - Influences sur la Vaporisation et la Combustion Induite." Phd thesis, Université de Rouen, 2007. http://tel.archives-ouvertes.fr/tel-00707588.
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Les contraintes actuelles, écologiques et économiques, imposent aux constructeurs automobiles de réduire la consommation et les émissions polluantes des moteurs Diesel. Pour améliorer ces derniers, il faut comprendre finement les phénomènes physiques mis en jeu et en particulier l'injection du carburant dans la chambre de combustion. Une voie d'analyse de la physique et d'optimisation des moteurs Diesel à injection directe est la simulation numérique et plus particulièrement la modélisation. Après avoir détaillé les caractéristiques physiques des sprays, les modélisations existantes du processus d'atomisation ainsi que leurs limitations, un modèle innovant est présenté : le modèle ELSA (pour Euler - Lagrange pour les Sprays et l'Atomisation). Il prend en compte l'écoulement dans la zone dense du spray et traite le phénomène d'atomisation depuis l'intérieur de l'injecteur jusque dans la zone diluée du spray. Les équations fondamentales de ce modèle sont l'équation de transport de la fraction massique moyenne de liquide et l'équation de transport de la densité massique moyenne d'interface liquide/gaz. Dans ces deux équations apparaît un terme de flux turbulent non fermé. Une méthode de couplage des formalismes eulérien et lagrangien est proposée pour sa fermeture. De plus, en prenant en compte chacun des phénomènes physiques agissant sur la quantité d'aire interfaciale liquide/gaz, des évolutions sur la fermeture de cette équation de transport sont apportées. Enfin, les échanges thermique et massique entre les phases liquide et gaz sont intégrés au modèle ELSA à l'aide de deux équations de transport : une pour la fraction massique de vapeur et une pour l'enthalpie massique de la phase liquide. Des cas de validations sont présentés, concernant tout d'abord une étude comparative en zone dense du jet avec des données issues d'une simulation numérique directe puis à l'aide de données expérimentales macroscopiques comme les pénétrations liquide et vapeur pour un spray vaporisant ou le positionnement de flamme dans le cas d'une combustion diphasique en régime stationnaire.
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Fartouk, Avner. "Modélisation de l'interaction entre un spray de gouttelettes d'eau et la combustion turbulente : Application au procédé d'extinction d'un foyer incendie par brouillards d'eau." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2013. http://tel.archives-ouvertes.fr/tel-00802164.
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Dans le cadre de la sécurité incendie, et de la prévention de départ d'un feu en environnement confiné, un objectif majeur consiste en l'amélioration des procédés d'extinction et plus précisément de la pulvérisation de brouillards d'eau qui est un moyen de lutte largement utilisé. Les simulations numériques doivent prévoir l'efficacité des brouillards en évaluant précisément l'évolution spatiotemporelle des caractéristiques du foyer incendie en présence d'un champ pulvérisé de gouttelettes. Pour déterminer les fractions massiques d'eau sous forme liquide ou vapeur, les concentrations des produits formés ainsi que les niveaux de températures en tout point du local, nous présentons ici le développement d'un modèle apte à décrire un milieu réactif dans lequel la stabilité de la flamme est altérée par la présence de gouttelettes d'eau. Un formalisme diphasique eulérien-eulérien est utilisé pour modéliser le transport des gouttelettes qui interagissent avec le milieu réactif en le refroidissant et en le diluant via l'introduction de vapeur d'eau issue du processus d'évaporation. Le modèle sousjacent est une approche de combustion à multi-fractions de mélange avec un diagramme de reconstitution des espèces mettant en compétition un domaine inflammable et un domaine non inflammable. Les modèles finalement obtenus ont été implantés dans Code_Saturne, un logiciel de mécanique des fluides qui a récemment été adapté à l'étude des incendies. La validation de ces modèles a été effectuée à partir de données expérimentales issues de la littérature, et sur des cas test d'échelle intégrale.
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Li, Haiying. "CFD modelling study of sprays and combustion of gasoline and DMF in direct injection gasoline engines." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4491/.
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The new biofuel candidate, 2, 5-Dimethylfuran (DMF) has received increasing interest as a potential alternative to fossil fuels, owing to the recent development of its new production technology. However, the effect of DMF properties on the fuel spray and vaporization, subsequent combustion processes and emission formation in the current Gasoline Direct Injection (GDI) engine is still not well understood. To investigate spray and combustion characteristics of DMF and explore possible applications to the IC engines, a three-dimensional Computational Fluid Dynamics (CFD) model has been developed using the KIVA3V code with improved spray models (nozzle flow model, spray atomization and secondary breakup models) and combustion models. This CFD model was validated by the optical diagnostics and then applied to study the in-cylinder mixture preparation and combustion characteristics of DMF in a GDI engine. The mixture preparation analysis shows both insufficient mixing time and significant spray-wall interaction when DMF is used result in relatively poor air/fuel distributions. Compared to the nearly homogeneous mixture with the gasoline fuel spray, a very rich fuel-air mixture of 7.7% and extremely lean mixture of 4.7% of the total charge has been observed in the case of DMF at the end of compression stoke. The analysis of combustion characteristics compared with the case of gasoline show that slightly longer combustion duration of DMF results from its lower laminar flame speed. The higher anti-knocking quality of DMF makes more advanced spark timing possible which brings about higher peak pressure and temperature and higher IMEP.
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Sierra, Sanchez Patricia. "MODELISATION DE LA DISPERSION ET L'EVAPORATION DE SPRAYS DANS DES CHAMBRES DE COMBUSTION AERONAUTIQUES." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2012. http://tel.archives-ouvertes.fr/tel-00701105.
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De nos jours, la combustion représente encore un 90% de la production totale d'énergie au monde. La plupart des brûleurs de type industriel utilisent comme carburant des hydrocarbures en forme liquide. Cependant, un grand nombre d'études ont été dédiés aux flammes gazeuses et l'impact du spray liquide est encore loin d'être totalement compris. Le but de cette étude est l'amélioration de la modélisation des deux phénomènes principaux qui ont lieu entre l'atomisation du spray et la combustion, i.e. la dispersion des gouttes par la turbulence gazeuse et le procès d'évaporation dans le contexte de la Simulation Aux Grandes Echelles (SGE) des configurations complexes. Premièrement, l'approche Euler-Euler mésoscopique (Février et al. (2005)), basée sur une moyenne d'ensemble conditionnée et implémentée dans AVBP est améliorée. Le modèle de fermeture (Simonin et al. (2001); Kaufmann (2004)) pour les moments de deuxième ordre qui apparait dans les équations de transport résolues échoue quand appliqué à des configurations cisaillées (Riber (2007)). Plusieurs modèles proposés récemment par Masi (2010) et qui ont été valides a priori dans une configuration de nappe chargée de particules sont validés a posteriori dans la même configuration. Une analyse quantitative sur plusieurs cas avec diffèrent nombres de Stokes, nombres de Reynolds de la phase gazeuse et résolutions du maillage ont permit de retenir un modèle non-linéaire nommé 2EASM3, qui utilise le tenseur de déformations de la phase dispersée comme échelle de temps caractéristique. La deuxième partie a pour but l'amélioration du modèle d'évaporation implémenté dans AVBP. Ce modèle suppose une conduction infinie dans la phase liquide et symétrie sphérique dans la phase gazeuse ainsi que des lois simplifiées pour les propriétés thermodynamiques et de transport. Un nouveau modèle prenant en compte la dépendance de la viscosité du mélange gazeux avec la composition locale, et des nombres de Prandtl et Schmidt fixés par les valeurs à l'équilibre obtenus par moyen d'une simulation prenant en compte des lois complexes pour les propriétés thermodynamiques et de transport est proposé. Cette nouvelle méthode produit des résultats en bon accord avec les mesures expérimentales pour l'évaporation d'une goutte isolée en une atmosphère d'azote au calme sans pourtant augmenter le cout du calcul. Finalement, l'impact des nouveaux modèles est analysé dans une SGE de la configuration semi-industrielle MERCATO (García-Rosa (2008)). Bien que les données expérimentales ne soient pas suffisantes pour confirmer les résultats, les distributions de gouttes et de carburant gazeux sont significativement affectés par les modèles, ce qui pourrait avoir un impact direct sur le procès d'allumage.
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Kah, Damien. "Prise en compte des aspects polydispensés pour la modélisation d'un jet de carburant dans les moteurs à combustion interne." Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00628908/en/.
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Le contexte général de cette thèse est la simulation numérique de l'injection de carburant dans un moteur à combustion interne, afin d'améliorer son rendement et de limiter la production de polluants. De manière plus générale, ce travail s'applique à tout système industriel mettant en jeu un écoulement multiphasique constitué d'un carburant liquide injecté dans une chambre occupée initialement par du gaz, comme par exemple les moteurs automobiles ou aéronautiques, ou les turbomachines. Intrinsèquement, il est possible de simuler l'ensemble de l'écoulement avec les équations classiques de la dynamique des fluides sans avoir recours à des outils de modélisation supplémentaires liés au caractère diphasique. Mais, les tailles des structures générées pendant l'injection (gouttes de diamètre inférieur à 10 μm) conduisent à des temps de calculs prohibitifs pour une application industrielle. C'est pourquoi il est nécessaire d'introduire une modélisation diphasique. C'est dans ce contexte que deux régions sont formellement distinguées: le coeur liquide dense proche de l'injecteur, appelé écoulement à phases séparées, et le spray constitué d'une population de gouttes polydisperse (c'est-à-dire de tailles différentes) générées après le processus d'atomisation en aval de l'injecteur. Ce travail de thèse étudie les modèles Eulériens pour la description de spray évaporants et polydisperses, en vue d'applications industrielles. Ils représentent une alternative potentielle aux modèles Lagrangiens qui sont majoritairement utilisés en industrie mais présentant des inconvénients majeurs. Ainsi, le modèle multi-fluide est étudié dans un premier temps. Bien que prometteur, deux difficultés sont soulignées: le coût requis pour une description précise de la polydispersion, et son incapacité à décrire les croisements de gouttes (particle trajectory crossing, PTC, en anglais). La thèse propose des solutions à ces deux limitations. Ces solutions reposent chacune sur des méthodes de moments. Premièrement, le modèle appelé Eulerian Size Multi Size Moment (EMSM) permet de résoudre des sprays évaporants et polydisperses de manière bien plus efficace que le modèle multi-fluide. Des outils mathématiques sont utilisés pour fermer le système d'équations associé au modèle, et combinés à des schémas de types volumes finis appelés schémas cinétiques, afin de préserver la réalisabilité du vecteur de moments, pour le transport et l'évaporation. Une réponse à la seconde limitation est apportée avec le modèle appelé Eulerian Multi Velocity Moment (EMVM) basé sur le transport de moments en vitesse d'ordre élevé. Une distribution bimodale peut être localement reconstruite à partir des moments en utilisant une méthode de quadrature de moments (Quadrature Method of Moment, QMOM en anglais) en une ou plusieurs dimensions d'espace. De la même manière que précédemment, l'utilisation de schémas cinétiques permet de préserver la réalisabilité du vecteur de moment. De plus, une étude mathématique approfondie de la dynamique du système en une dimension d'espace en révèle toute la complexité et représente une étape indispensable en vue de l'élaboration de schémas de transport d'ordre élevé (supérieur ou égal à 2).Afin de les tester, ces deux modèles ainsi que les outils numériques associés sont implémentés dans MUSES3D, un code académique de simulation numérique directe (Direct Numerical Simulation DNS en anglais) dédié à l'évaluation des modèles de spray. Des résultats de grande qualité démontrent le potentiel des modèles. L'extension du modèle EMSM dans un contexte industriel est ensuite considérée, avec son implémentation dans IFP-C3D, un code résolvant des écoulements réactifs sur des maillages non structurés et mobiles (dû au mouvement du piston) dans un formalisme RANS (Reynolds Averaged Navier Stokes) en présence de sprays. Le formalisme ALE (Arbitrary Lagrangian Eulerian en anglais) est utilisé et le modèle EMSM réécrit dans ce formalisme afin de mener des calculs en maillage mobile. De plus, une étude numérique a permis d'étendre les propriétés de précision et de stabilité obtenues en maillage fixe. La robustesse du modèle EMSM est alors démontrée avec succès dans IFP-C3D sur un cas impliquant un mouvement de piston, ainsi que dans le cadre d'une comparaison avec le code MUSES3D. Enfin, des résultats très encourageants prouvent la faisabilité d'un calcul d'injection dans une chambre de combustion d'un spray polydisperse avec le modèle EMSM.
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Jaegle, Félix. "LARGE EDDY SIMULATION OF EVAPORATING SPRAYS IN COMPLEX GEOMETRIES USING EULERIAN AND LAGRANGIAN METHODS." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2009. http://tel.archives-ouvertes.fr/tel-00452501.
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Dû aux efforts apportés à la réduction des émissions de NOx dans des chambres de combustion aéronautiques il y a une tendance récente vers des systèmes à combustion pauvre. Cela résulte dans l'apparition de nouveaux types d'injecteur qui sont caractérisés par une complexité géométrique accrue et par des nouvelles stratégies pour l'injection du carburant liquide, comme des systèmes multi-point. Les deux éléments créent des exigences supplémentaires pour des outils de simulation numériques. La simulation à grandes échelles (SGE ou LES en anglais) est aujourd'hui considérée comme la méthode la plus prometteuse pour capturer des phénomènes d'écoulement complexes qui apparaissent dans une telle application. Dans le présent travail, deux sujets principaux sont abordés: Le premier est le traitement de la paroi ce qui nécessite une modélisation qui reste délicate en SGE, en particulier dans des géométries complexes. Une nouvelle méthode d'implémentation pour des lois de paroi est proposée. Une étude dans une géométrie réaliste démontre que la nouvelle formulation donne de meilleurs résultats comparé à l'implémentation classique. Ensuite, la capacité d'une approche SGE typique (utilisant des lois de paroi) de prédire la perte de charge dans une géométrie représentative est analysée et des sources d'erreur sont identifiées. Le deuxième sujet est la simulation du carburant liquide dans une chambre de combustion. Avec des méthodes Eulériennes et Lagrangiennes, deux approches sont disponibles pour cette tâche. La méthode Eulérienne considère un spray de gouttelettes comme un milieu continu pour lequel on peut écrire des équations de transport. Dans la formulation Lagrangienne, des gouttes individuelles sont suivies ce qui mène à des équations simples. D'autre part, sur le plan numérique, le grand nombre de gouttes à traiter peut s'avérer délicat. La comparaison des deux méthodes sous conditions identiques (solveur gazeux, modèles physiques) est un aspect central du présent travail. Les phénomènes les plus importants dans ce contexte sont l'évaporation ainsi que le problème d'injection d'un jet liquide dans un écoulement gazeux transverse ce qui correspond à une version simplifiée d'un système multi-point. Le cas d'application final est la configuration d'un seul injecteur aéronautique, monté dans un banc d'essai expérimental. Ceci permet d'appliquer de manière simultanée tous les développements préliminaires de ce travail. L'écoulement considéré est non-réactif mais à part cela il correspond au régime ralenti d'un moteur d'avion. Dû aux conditions préchauffées, le spray issu du sstème d'injection multi-point s'évapore dans la chambre. Cet écoulement est simulé, utilisant les approaches Eulériennes et Lagrangiennes et les résultats sont comparés aux données expérimentales.
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Heising, Raymond. "Effectiveness of pulsed spray combustion for suppression of combustion instabilities." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16682.
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Mohd, Yasin Mohd Fairus Bin. "Modelling of biodiesel spray combustion." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648856.
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Majhool, Ahmed Abed Al-Kadhem. "Advanced spray and combustion modelling." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/advanced-spray-and-combustion-modelling(eb3ef22a-53d0-4e70-aa9d-bec37775d451).html.
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The thesis presents work across three different subjects of investigations into the modelling of spray development and its interaction with non-reactive and reactive flow. The first part of this research is aimed to create a new and robust family of convective scheme to capture the interface between the dispersed and the carrier phases without the need to build up the interface boundary. The selection of Weighted Average Flux (WAF) scheme is due to this scheme being designed to deal with random flux scheme which is second-order accurate in space and time. The convective flux in each cell face utilizes the WAF scheme blended with Switching Technique for Advection and Capturing of Surfaces (STACS) scheme for high resolution flux limiters. However in the next step, the high resolution scheme is blended with the scheme to provide the sharpness and boundedness of the interface by using switching strategy. The proposed scheme is tested on capturing the spray edges in modelling hollow cone type sprays without need to reconstruct two-phase interface. A test comparison between TVD scheme and WAF scheme using the same flux limiter on convective flow on hollow cone spray is presented. Results show that the WAF scheme gives better prediction than the TVD scheme. The only way to check the accuracy of the presented models are evaluations according to physical droplets behaviour and its interaction with air. In the second part, due to the effect of evaporation the temperature profile in the released fuel vapour has been proposed. The underlying equation utilizes transported vapour mass fraction. It can be used along with the solution of heat transfer inside a sphere. After applying boundary conditions, the equation can provide a solution of existing conditions at liquid-gas interface undergoing evaporation and it is put in a form similar to well-known one-third rule equation. The resulting equation is quadratic type that gives an accurate prediction for the thermo-physical properties due to the non-linear relation between measured properties and temperature. Comparisons are made with one-third rule where both equations are implemented in simulating hollow cone spray under evaporation conditions. The results show the presumed equation performs better than one-third rule in all comparisons. The third part of this research is about a conceptual model for turbulent spray combustion for two combustion regimes that has been proposed and tested for n-heptane solid cone spray type injected into a high-pressure, high-temperature open reactor by comparing to the available experimental data and to results obtained using two well known combustion models named the Combined Combustion Model (CCM) and the unsteady two-dimensional conditional moment closure (CMC) model. A single-zone intermittent beta-two equation turbulent model is suggested to characterise the Lumped zone. This model can handle both unburned and burned zones. Intermittency theory is used to account for the spatially non-uniform distribution of viscous dissipation. The model suggests that the Lumped zone can be identified by using the concept of Tennekes and Kuo-Corrsion of isotropic turbulence that suggests that dissipative eddies are most probably formed as vortex tubes with a diameter of the order of Kolmogorov length scale and a space of the order of Taylor length scale. Due to the complexity of mixture motion in the combustion chamber, there exist coherent turbulent small scale structures containing highly dissipative vortices. The small size eddies play an important role in extinguishing a diffusion spray flame and have an effect on the combustion reaction at molecular scale because small scales turbulence increase heat transfer due to the dissipation. A common hypothesis in constructing part of the model is if the Kolmogorov length scale is larger than the turbulent flame thickness. The Lumped strategy benefits from capturing small reactive scales information provided by numerics to improve the modelling and understand the exact implementation of the underlying chemical hypothesis. The Lumped rate is estimated from the ratio of the turbulent diffusion to reaction flame thickness. Three different initial gas temperature test cases are implemented in simulations. Lumped spray combustion model shows a very good agreement with available experimental data concerning auto-ignition delay points.
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Cannevière, Karine. "Simulation Numérique Directe de la combustion turbulente diphasique: Application à l'étude de la propagation et de la structure des flammes." Phd thesis, INSA de Rouen, 2003. http://tel.archives-ouvertes.fr/tel-00006820.
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Ce travail est consacré à l'étude de la propagation et de la structure des flammes dans le cas des écoulements turbulents diphasiques. Pour cela, un code de simulation numérique directe (DNS) est utilisé. Les équations et le modèle chimique employés dans le code de DNS sont tout d'abord présentés. Ensuite, une étude des flammes diphasiques laminaires est réalisée. Dans un premier temps, une étude analytique portant sur la dynamique d'évaporation des gouttes est proposée. L'influence importante sur le mode de combustion du rapport entre le temps de préchauffage de la goutte et le temps d'évaporation, est mise en évidence. La simulation de la propagation d'une flamme au sein d'un nuage de gouttes est réalisée et un comportement de flamme pulsée est abordée. Une étude de ces flammes en fonction de la topologie du combustible liquide nous a permis de montrer qu'elles avaient une structure de flamme double composée d'une flamme de prémélange suivie d'une flamme de diffusion. L'étude des flammes turbulentes diphasiques fait l'objet de notre dernière étude. Des DNS de l'injection de sprays monodisperses sont effectuées en variant les paramètres d'injection de la phase liquide (densité, rapport d'équivalence). La base de données obtenue nous permet de décrire les régimes de flamme locaux et globaux apparaissant dans la combustion de sprays, et qui sont répertoriés en quatre familles principales : régime externe ouvert et fermé, combustion de groupe et combustion mixte. Enfin, un diagramme de combustion est développé, impliquant le temps d'évaporation des gouttes, la distance inter-gouttes ou inter-groupes de gouttes, et enfin le rapport d'équivalence injecté.
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Verdier, Antoine. "Experimental study of dilute spray combustion." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMIR27/document.
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La combustion diphasique implique de nombreux phénomènes physiques complexes, comprenant l'atomisation, la dispersion, l'évaporation et la combustion. Bien que la simulation numérique soit un outil performant pour aborder ces différentes interactions entre les phases liquides et gazeuses, la méthode doit être validée par des études expérimentales fiables. Par conséquent, des données expérimentales précises sur la structure de la flamme et sur les propriétés de la phase liquide et gazeuse le long des étapes d'évaporation et de combustion sont nécessaires. La complexité des configurations aéronautiques réelles implique d'étudier l'effet des propriétés locales sur la dynamique des flammes pour une configuration canonique. Ce travail, réalisé dans le cadre du projet ANR TIMBER, a pour objectif d'améliorer la compréhension de la combustion en flux diphasique, ainsi que de produire une base de données efficace et originale pour la validation des modèles utilisés dans les LES<br>Liquid fuels are the primary energy source in a wide range of applications including industrial and residential furnaces, internal combustion engines and propulsion systems. Pollutant emission reduction is currently one of the major constraints for the design of the next generation combustion chamber. Spray combustion involves many complex physical phenomena including atomization, dispersion, evaporation and combustion, which generally take place simultaneously or within very small regions in the combustion chambers. Although numerical simulation is a valuable tool to tackle these different interactions between liquid and gas phases, the method needs to be validated through reliable experimental studies. Therefore, accurate experimental data on flame structure and on liquid and gas properties along the evaporation and combustion steps are needed and are still challenging. A joint effort between numerical and experimental teams is necessary to meet tomorrow's energy challenges and opportunities. The complexity of the real aeronautical configurations implies to study the effect of local properties in flame dynamics on a canonical configuration, which presents the essential feature of very well defined boundary conditions. This work, carried out within the framework of the ANR TIMBER project, aims to improve the understanding of two-phase flow combustion, as well as to produce an efficient and original database for the validation of the models used in LES
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Matheson, Tomas. "Presumed pdf modelling for turbulent spray combustion." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/413770/.
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Bhikuning, Annisa. "Spray and combustion characteristics in biodiesel fuels." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13127440/?lang=0, 2020. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13127440/?lang=0.
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バイオディーゼルは、メタノールと触媒を使用したエステル交換プロセスによって製造されます。バイオディーゼルには、高セタン価、酸化安定性、低排出など、いくつかの利点があります。ただし、バイオディーゼルの高粘度と沸騰温度は、ディーゼルエンジンの噴霧燃焼に影響を与える可能性があります。したがって、高燃料と低沸点燃料を混合することでバイオディーゼルの特性を改善するために、新しい燃料設計法が適用されます。<br>Biodiesel is one of the promising alternative fuels in the future. Biodiesel is made from the trans-esterification process that uses methanol or alcohol and catalyst. The use of biodiesel in diesel engine has some advantages such as high cetane number, oxidation stability and can reduce some emissions. However, high viscosity, boiling temperatures and surface tension in biodiesel may affect the spray characteristics as compared to diesel oil. To overcome the unbenefited in biodiesel, therefore, the new fuel designed method that high-boiling point fuel is mixed to a low-boiling point fuel is applied in order to improve the properties in biodiesels.<br>博士(工学)<br>Doctor of Philosophy in Engineering<br>同志社大学<br>Doshisha University
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Bishop, Robert Phelps. "Combustion efficiency in internal combustion engines." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15164.
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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.<br>MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING<br>Bibliography: leaf 26.<br>by Robert Phelps Bishop.<br>B.S.
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Rajakaruna, Hobinanuwan Tikiri Banda. "A mathematical model for liquid fuel spray combustion." Thesis, De Montfort University, 1997. http://hdl.handle.net/2086/5207.
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Schroll, Peter. "Conditional moment closure for spray combustion and ignition." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609129.
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Fujita, Akitoshi. "Numerical Simulations of Spray Combustion and Droplet Evaporation." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142213.
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Kolakaluri, Ravi. "Engine spray combustion modeling using unified spray model with dynamic mesh refinement." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1468103.
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Tabrizi, Behzad Samadzadeh. "Three-dimensional diesel spray predictions in combustion chamber flows." Thesis, Imperial College London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287861.
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Ribeiro, Mateus Dias. "Fuel spray modeling for application in internal combustion engines /." Guaratinguetá, 2019. http://hdl.handle.net/11449/183102.
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Orientador: José Antônio Perrella Balestieri<br>Abstract: Direct injection spark ignition (DISI) engines aim at reducing specific fuel consumption and achieving the strict emission standards in state of the art internal combustion engines. Therefore, in this work the goal is to develop code for simulations of the internal flow in DISI engines, as well as the phenomenon of fuel spray injection into the combustion chamber using a Lagrangian-Eulerian approach for representing the multiphase flow, and Large-eddy Simulations (LES) for modeling the turbulence of the continuum medium by means of the open-source CFD library OpenFOAM. In order to validate the obtained results and the developed models, experimental data from the Darmstadt optical engine, and the non-reactive “Spray G” gasoline injection case, along with the reactive “Spray A” case from the Engine Combustion Network (ECN) will be employed. Finally, a novel open-source solver will be proposed to simulate the Darmstadt optical engine in motored and fired operation under stratified mixture condition, using data compiled by the Darmstadt Engine Workshop (DEW) for validation. Moreover, a deep learning framework is presented to train an artificial neural network (ANN) with the engine LES data generated in this work, in order to make predictions of the small scale turbulence behavior.<br>Resumo: Motores de ignição a centelha com injeção direta (direct injection spark ignition engines, DISI engines) visam reduzir o consumo específico de combustível e respeitar os restritos níveis de emissão em motores de combustão interna de última geração. Assim, pretende-se com este trabalho desenvolver código para simulação do escoamento interno em motores DISI, assim como os fenômenos de injeção de combustível no interior da câmara de combustão utilizando uma abordagem Lagrangeana-Euleriana para representação do escoamento multifásico e Simulação de Grandes Escalas (Large-eddy simulation, LES) para a modelagem da turbulência no meio contínuo, por intermédio da biblioteca CFD de código aberto OpenFOAM. De modo a validar os resultados e os modelos desenvolvidos, dados experimentais serão utilizados, obtidos do motor óptico de Darmstadt, e do caso de teste de injeção de gasolina não-reativo “Spray G”, juntamente com o caso reativo “Spray A” da Rede de Combustão em Motores (Engine Combustion Network, ECN). Enfim, um novo código aberto será proposto para simular o motor óptico de Darmstadt em condições de escoamento a frio (sem combustão) e com combustão em condição de mistura estratificada, usando dados compilados pelo Workshop do Motor de Darmstadt (Darmstadt Engine Workshop, DEW) para validação. Além disso, uma abordagem de aprendizado profundo (deep learning) será apresentada para treinar uma rede neural artificial (artificial neural network, ANN) com dados de simulação LES de moto... (Resumo completo, clicar acesso eletrônico abaixo)<br>Doutor
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Zhu, Min. "Modelling and simulation of spray combustion with PDF methods." Thesis, University of Cambridge, 1996. https://www.repository.cam.ac.uk/handle/1810/272496.
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Cho, Sung Taek. "Spray development and combustion in direct injection diesel engines." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/8638.
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Metzger, Brian. "Glycerol Combustion." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-07312007-153859/.
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As worldwide production of biodiesel fuel increases, one of the largest concerns is the abundance of waste glycerol. The price of crude glycerol has fallen drastically and many large biodiesel producers are currently paying to landfill this large waste stream. In the search to find a value added alternative, glycerol combustion may be one of the simplest solutions. Heat recovered from glycerol oxidation could easily be used to reduce heating costs inherent to large-scale biodiesel production. It has been stated ?Combustion of glycerol would be an elegant solution, if it worked?. Clean combustion of glycerol is difficult due to its high viscosity, high auto ignition temperature, and concerns of hazardous emissions. In particular, most in the biodiesel producing community share a fear that burning glycerol could produce acrolein, an aldehyde which is a thermal decomposition product of glycerol and is toxic at very low concentrations. This report will detail the design of a burner that can safely and easily burn crude glycerol for process heating. Emissions testing in the burner using glycerol sources of varying quality confirm that this burner design completely oxidizes the glycerol into CO2 and H2O with very low levels of pollutants, typical of other hydrocarbon fuels. These results show that safe, clean, and efficient combustion of a wide range of glycerol purities is possible with a properly designed burner.
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Elmedhem, Bashir A. "Modelling of liquid fuel combustion in furnaces." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325303.
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Bai, Chengxin. "Modelling of spray impingement processes." Thesis, Online version, 1996. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.299814.
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Ghorbali, Ali. "Cyclic variation in combustion in a constant volume combustion chamber." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6757.
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Cycle to cycle variations in combustion and turbulence characteristics in a swirling flow were measured in a cylindrical vessel. The vessel was charged by rapid tangential injection using a shrouded valve for two valve lifts (7 mm and 12 mm). A premixed lean mixture of propane and air ($\phi$ = 0.8) was ignited at quarter radius from the center. Pressure rise as a function of time was measured using a pressure transducer. Mean flow, turbulence intensity and Taylor microscale were estimated by statistical analysis of a single hot wire anemometer signal using ensemble averaging and cyclic analysis. Results obtained indicate that changing the valve lift changes turbulence characteristics at mid-radius. However, turbulence characteristics at quarter radius from center and quarter radius to wall were found to be independent of valve lift. Mean time, standard deviation of mean time delay and Taylor microscale were estimated using combustion pressure traces. Results indicate that the mean time and the standard deviation ignition are weak functions of mean flow and turbulence intensity and strong functions of the Taylor microscale as implied by the Tennekes model. Cyclic variations at ignition were observed to contribute the most to cyclic variations.
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Wright, Yuri Martin. "Numerical investigation of turbulent spray combustion with conditional moment closure /." Zürich : ETH, 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16386.
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Wang, De Ming. "Modelling spray wall impaction and combustion processes of diesel engines." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260644.
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Salcedo, Saulo Alfredo Gómez. "CFD analysis in spray combustion using a pressure swirl injector." Instituto Tecnológico de Aeronáutica, 2015. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3292.
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The object of this work is to apply CFD simulation in the description of the spray burning. As a case study, a pressure swirl injector, characterized and tested by NIST, has been chosen, which atomize liquid kerosene in an atmosphere of gaseous oxygen. The chamber dimensions allow a complete evaporation, avoiding the impact of drops on the circular wall. Swirl-axisymmetric domain and steady state permit to include combustion, a complex process, without requiring of high computational resources. Continuous phase is treated with an Eulerian reference, while fuel drops are tracked following the Lagrangian formulation. Chemical kinetics is reduced to the concept of mixture fraction. This assumption avoids the solution of too many transport equations for all involved species. In the first simulation, the inlet boundary of the continuous phase is obtained from the numerical solution of a fully developed flow transporting the oxidant gas. Then, four cases are proposed and solved, changing the turbulence intensity and swirl velocity on the inlet boundary, each parameter with two different values. Finally, results for the axial velocity, streamlines, drops trajectories, temperature, distribution and total production of selected species are analyzed and compared with other related studies.
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Paulhiac, Damien. "Modélisation de la combustion d’un spray dans un brûleur aéronautique." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14495/1/paulhiac_partie_1_sur_2.pdf.
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La combustion d’hydrocarbures représente encore aujourd’hui une part très majoritaire de la production d’énergie mondiale, en particulier dans la propulsion aérospatiale. La plupart des brûleurs industriels sont alimentés par un carburant sous forme liquide, qui est injecté directement dans la chambre de combustion, ce qui génère une forte interaction entre le spray, l’écoulement turbulent et la zone de combustion. Cette interaction a déjà largement été étudiée, mais certaines questions restent ouvertes. En particulier, la prise en compte de la combustion de goutte isolée dans le cadre de la Simulation aux Grandes Echelles (‘Large Eddy Simulation’ LES) de géométries complexes reste un problème difficile. L’objectif de cette thèse est d’améliorer la modélisation de la combustion du spray dans le contexte de la LES de configurations complexes avec une approche Euler-Lagrange. Dans un premier temps, un modèle de combustion de gouttes incluant les différents régimes pour la LES, appelé MustARD pour « Multi-State Algorithm for Reacting Droplets », est proposé et validé dans plusieurs configurations académiques de complexité croissante. Dans un deuxième temps, MustARD est évalué sur une configuration de brûleur expérimental et comparé aux modèles classiques sans combustion de gouttes isolées. Cette étude montre que le régime de combustion de gouttes isolées n’est pas négligeable dans une telle configuration et qu’il modifie la structure de flamme. D’autre part, les comparaisons avec les résultats expérimentaux montrent que le modèle MustARD permet d’améliorer la précision des LES de sprays turbulents réactifs.
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Martin, Kendrick. "Switchgrass combustion studies." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29537.
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This thesis presents fundamental research about the combustion gas products and solid phase residue of switch grass combustion. To identify the compounds released during the combustion phase, tests were conducted using a Thermogravimetric Analyzer (TGA) coupled to a Fourier Transform Infrared Spectrometer. These test revealed that aromatic compounds as well as carbon dioxide and water were released.<br>High Pressure Liquid Chromatography (HPLC) and GCMS/GCFID were also used to identify and semi-quantify polycyclic aromatic hydrocarbons (PAH) and benzene derivatives. From these analyses it was concluded that thermal synthesis was not occurring within an oxidative environment and as such no PAHs were found.<br>Finally an infrared microscope and a scanning electron microscope were used to study functional group, morphology and metal content change resulting from the combustion process.<br>This research provided information about the combustion mechanism of switch grass and laid the foundation for pilot-scale testing.
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Cairns, Malcolm. "Titanium particle combustion." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86572.
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In order to increase the validity of numerical models of the detonation of heterogeneous titanium explosives, experimental results are needed. The combustino of titanium is studied using two experimental techniques. The first technique is the study of the burn time for a single particle over a wide range of initial diameters while altering the oxygen concentration. To accomplish this a new flat flame burner to study particle burn time has been designed. Luminous tracks caused by the light emitted by the combustion of the particles are analyzed and burn time is inferred. Burn time in air and in an oxygen enriched atmosphere were determined. A second experiment involves the study of large scale detonation of heterogeneous charges. The charges are filled with nitromethane and a packed bed of titanium particles. The titanium particles varied in morphology and particles size. A critical charge diameter for charge ignition (CDPI) was found for irregularly shaped particles but was not found for spherical particles.<br>Pour augmenter la validit des modles numriques sur dtonation d'explosifs htrognes contenants du titane , des rsultats exprimentaux sont ncessaires. Le combustino de titane est tudi en utilisant deux techniques exprimentales. La premire technique est l'tude du temps brle pour une particule sur une large gamme de diamtres initiaux en changeant la concentration d'oxygne. Pour l'accomplir un nouveau brleur de flamme plat pour tudier la particule brle le temps a t conu. Les empreintes lumineuses provoques par la lumire mise par la combustion des particules sont analyses et brlent le temps est dduit. Brlez le temps dans l'air et dans l'atmosphre enrichie d'un oxygne ont t dtermins. Une deuxime exprience implique l'tude de grande dtonation d'chelle de charges htrognes. Les charges sont remplies de nitromethane et un lit emball de particules de titane. Les particules de titane variaient dans la grandeur de particules et la morphologie. Un diamtre de charge critique pour l'ignition de charge (CDPI) a t trouv pour les particules irrgulirement en forme de, mais n'a pas t trouv pour pour les particules irrgulirement en forme de mais n'a pas t trouv pour les particules sphriques.
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Dutko, Alexander C. "Acoustic enhancement of water spray evaporation within a pulse combustor." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17872.
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Guézennec, Nicolas. "Contrôle actif de la combustion diphasique." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0022/document.
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L’application de cette thèse est le contrôle actif de la combustion dans les brûleurs industriels à combustible liquide. Il s’agit d’explorer les possibilités de contrôle d’un spray par des jets gazeux auxiliaires. Deux familles d’actionneurs utilisant ce procédé ont été testées sur un atomiseur coaxial assisté par air. Le premier dispositif est appelé (Dev). Composé d’un unique jet actionneur, il vise à dévier le spray. La seconde configuration, appelée (Sw), est équipée de 4 jets auxiliaires tangents au spray afin de lui conférer un effet de swirl et d’en augmenter le taux d’expansion. Les mesures de granulométrie par PDA et les visualisations du spray par strioscopie démontrent un effet important du contrôle sur l’atomisation et la forme du spray. On observe en outre une déviation pouvant atteindre 30°avec l’actionneur (Dev) et une augmentation du taux d’expansion de 80% dans le cas (Sw). Des simulations du banc expérimental ont de plus été menées avec le code AVBP. L’écoulement de gaz est calculé par simulation aux grandes échelles (SGE ou LES en Anglais). L’approche lagrangienne est utilisée pour simuler la phase dispersée. Une attention particulière a été portée aux conditions d’injection du gaz et des gouttes dans le calcul. Ceci a abouti au développement d’une nouvelle condition limite caractéristique non réfléchissante (VFCBC) destinée à l’injection d’écoulements turbulents en LES compressible. Les résultats de LES présentent un bon accord avec les mesures expérimentales. Les effets du contrôle sur la dynamique des gouttes et sur la topologie du spray (forme, déviation, expansion) sont correctement décrits<br>The present work focuses on active control of two-phase combustion in industrial burners. The generic method explored in this thesis consists in controlling the injected fuel spray with transverse air jets. Two families of these jet actuators are tested on a coaxial airblast atomizer. The first system (Dev) is used to modify the trajectory of the spray, while the second one (Sw) introduces swirl into the spray to modify its spreading rate and mixing with the surrounding air. Experimental characterisations of the controlled flow with Schlieren visualisations and Phase Doppler Anemometry (PDA) show that actuators induce important effect on the spray. The deviation angle reaches 30° for the actuator (Dev) and the expansion rate increases of 80 % in the swirl case (Sw). Simulations of the experiment are then performed with the CFD code AVBP. The gas flow is computed with Large Eddy Simulation (LES). A Lagrangian formulation is used to simulate droplets trajectories. A particular attention is given to the injection of the gas flow and the droplets in the calculations. Therefore, a new non-reflecting characteristic boundary condition (VFCBC) has been derived to inject turbulent flows in compressible LES. A good agreement is observed between simulation and experiment. Control effects on the spray topology ( features, deviation, spread rate) and on the droplets velocities and diameters are correctly described by the Lagrangian LES
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YAMAMOTO, Kazuhiro, 和弘 山本, 博史 山下, 康太 萩原, Hiroshi YAMASHITA та Kouta HAGIHARA. "噴霧燃焼の燃焼形態に与える液滴の大きさと数密度の影響に関する数値解析". 日本燃焼学会, 2009. http://hdl.handle.net/2237/19738.
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Rochaya, David. "Numerical simulation of spray combustion using bio-mass derived liquid fuels." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2231.
Full textAbstract:
The main objective of this work is to create a robust model for two-phase liquid spray
combustion flow using vegetable oils, to investigate the flow structure generated by a
swirler array with different fuels, and secondly to assess and optimise the capability of
the CFD to predict accurately the results obtained experimentally and eventually
enhance CFD model development and simulation. Validation is achieved by
comparing the numerical results obtained with CFD with the experimental
measurements.
The purpose of this research is to increase the scientific understanding of the
fundamental mechanisms of the spray combustion process using a carbon neutral fuel
such as ethanol and biodiesel. In fact, very few numerical simulations of liquid
biomass fuels in gas turbine systems are available in the literature.
The flames are simulated using the commercial code FLUENT. The
combustion/turbulence interaction is modelled using the laminar flamelet approach
with detailed chemistry modelled using the OPPDIFF model from CHEMKIN.
While the experiments could be carried out only up to 3 atm, the simulations were
further extended to a maximum pressure of 10 atm. The FLUENT results were
assessed qualitatively and quantitatively between the experimental measurements and
the simulation. The cold flow features have been captured by the present simulations
with a good degree of accuracy. Effect of air preheating was investigated for the
biodiesel, and sensitivity to droplet size and spray angles variation were analysed.
Good agreement was obtained for ethanol except in the fuel lean region due to failure
of the FLUENT laminar flamelet model to capture local flame extinction while
biodiesel simulation resulted in a significant overprediction of the flame temperature
especially in the downstream region and satisfactory results further upstream. The
results show the importance of setting proper droplet initial conditions, since it will
significantly affect the structure of the flame.
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Abdelsamie, Abouelmagd [Verfasser]. "Direct numerical simulations of turbulent flow and spray combustion / Abouelmagd Abdelsamie." Magdeburg : Universitätsbibliothek, 2017. http://d-nb.info/1136955100/34.
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SOUZA, OBERDAN MIGUEL RODRIGUES DE. "PRESUMED PDF MODEL WITH TABULATED CHEMICAL KINETIC APPLIED FOR SPRAY COMBUSTION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30283@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>PROGRAMA DE EXCELENCIA ACADEMICA<br>Neste trabalho, foi desenvolvida uma modificação do modelo para simulação de sprays Diesel com o método de PDF presumida e cinética química tabulada. Através do acoplamento entre a parte química e a parte
turbulenta, avaliou-se os efeitos do spray com a metodologia flamelet. Onde o conceito flamelet trata a chama difusiva e transiente como um conjunto de chamas unidimensionais, utilizando o modelo de PDF presumida para a avaliação dos valores turbulentos. A validação do modelo foi realizada com dados experimentais do laboratório Sandia, em uma câmara a volume constante. A validação e a aplicação do modelo foram conduzidas em diferentes tipos de ensaios experimentais: avaliação e comparação para
diferentes modelos de cinética química do n-heptano, validação do método para o modelo de turbulência K-epsilon na câmara de volume constante do Sandia para o n-heptano não reativo, validação e comparação do modelo para o spray reativo e aplicação de modelo para o estudo comprimento do ancoramento de chama e para o tempo de atraso de ignição do n-heptano para diferentes temperaturas ambientes. Em geral, a modelagem proposta tem demonstrado excelente capacidade de previsão para a combustão com spray Diesel numa vasta gama de aplicações e é um candidato altamente promissor para outras aplicações em motores Diesel.<br>In this work, a modification of the model for the simulation of diesel sprays with the presumed PDF method and tabulated chemical kinetics was developed. Through the coupling between the chemical part and the
turbulent part, the effects of the spray were evaluated for the flamelet methodology. Where the textit flamelet concept treats the diffusive and transient flame as a set of one-dimensional flames, using the presumed PDF model for the evaluation of turbulent values. The validation of the model was performed with experimental data from the Sandia laboratory, in a chamber at constant volume. The validation and application of the model were conducted in different types of experimental trials: evaluation and comparison for different chemical kinetics models of n-heptane, validation of the method for the turbulence model K-epsilon in the constant volume chamber of the Sandia for non-reactive n-heptane, validation and comparison of the model for the reactive spray and model application for the study of the flame anchoring length and for the ignition delay time of n-heptane at different ambient temperatures. In general, the proposed modeling has demonstrated excellent predictive capacity for diesel spray combustion in a wide range of applications and is a highly promising candidate for other applications in diesel engines.
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Librovich, Bronislav. "Modelling of group combustion of droplets in a spray fuel cloud." Thesis, University of Central Lancashire, 1999. http://clok.uclan.ac.uk/19287/.
Full textAbstract:
Release and combustion of a spray cloud in an atmosphere is a phenomenon encountered in a wide range of applications. For solution of a set of problems which is connected with ecology, theory of combustion and explosion, engine design, fire safety, etc. the knowledge of spray combustion behaviour is required. To investigate the influence of a variety in density and transport coefficients and flame front structure, combustion of pure gas cloud is studied numerically. Combustion of a small-scale spherical pocket of fuel droplets in a calm environment may be considered as a model enabling the transient combustion process to be studied conveniently in one-dimensional geometry. Apart from pure academic interest, such a study provides useful estimations of burning spray cloud characteristics which can be applied for the analysis of more complicated situations. An analytical approach is used to find quasi-steady state distributions of gas temperature and fuel mass fraction for both pure evaporating and burning clouds. This approach is quite fruitful, it gives important qualitative analytical relationships, which help to comprehend the complex process of evaporation or combustion of spray the cloud. Numerical method is used to solve the problem of spray cloud combustion using more common unsteady statement. Two types of ignition are used at the centre or from penphery of cloud. Two types of flames (premixed and diffusion flames) are observed in the numerical simulations. Distributions of all components and temperature are obtained at different moments of time for both types of ignition. The diffusion burning time and total evaporation time are estimated using numerical results.
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Sone, Kazuo. "Unsteady simulations of mixing and combustion in internal combustion engines." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12171.
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