Gas-Partikel-Stroemungen finden sich in weiten Bereichen der Energie- und Verfahrenstechnik. Beispiele fuer haeu- fig anzutreffende Problemstellungen sind der Transport, die Separation oder die Injektion eines Gemisches aus festen Partikeln und einem Traegergas. Fuer die numerische Simulation solcher disperser Mehr- phasenstroemungen hat sich das Lagrange-Verfahren als besonders geeignet erwiesen. Andererseits stellt die An- wendung dieses Berechnungsverfahrens hoechste Anforderun- gen an die Ressourcen der verwendeten Rechner. Dies gilt im besonderen Masse fuer die Simulation von Stroemungen mit einer moderaten bis hohen Partikelbeladung, in denen die Partikel-Partikel-Kollisionen einen grossen Einfluss auf das Stroemungsverhalten haben. Um das grosse Leistungspotential, das heutige massiv par- allele Hochleistungsrechner bieten, effizient zu nutzen, wurden im Rahmen dieser Arbeit parallele Simulationsalgo- rithmen fuer die numerische Berechnung kollisionsbehafte- ter Gas-Partikel-Stroemungen entwickelt. Die Effizienz dieser Algorithmen wurde anhand verschiedener Testfaelle untersucht. Auf der Grundlage der dabei erzielten Ergeb- nisse wurden Vorschlaege fuer weitere Entwicklungsmoeg- lichkeiten erarbeitet. / Gas-particle-flows can be found widely in the field of energy production and process engineering. Examples for applications of such kind of flows are transport, se- paration or injection of a mixture of solid particles and a gaseous phase. The Lagrangian approach has proved to be a suitable means for the numerical simulation of disperse multiphase flows. On the other hand its application requires a large amount of computational power, especially when flows with a mo- derate or high particle loading are computed and particle- particle collisions have a significant influence on the flow. In order to use efficiently the large computational power that parallel computers provide nowadays, parallel algo- rithms for the numerical simulation of gas-particle flows including particle-particle collisions were developed in the cource of this work. The algorithms' efficiency was investigated considering different test cases. On the basis of the results suggestions for further developments were made.

In this paper we present detailed Euler-Euler Large Eddy Simulations (LES) of dispersed bubbly flow in a rectangular bubble column. The motivation of this study is to investigate potential of this approach for the prediction of bubbly flows, in terms of mean quantities. The set of physical models describing the momentum exchange between the phases was chosen according to previous experiences of the authors. Experimental data, Euler-Lagrange LES and unsteady Euler-Euler Reynolds-Averaged Navier-Stokes model are used for comparison. It was found that the presented modelling combination provides good agreement with experimental data for the mean flow and liquid velocity fluctuations. The energy spectrum made from the resolved velocity from Euler-Euler LES is presented and discussed.

Accurate determination of the pressure losses at the bit is very important for drilling practices in petroleum industry. In the literature, there are several studies on determination of the pressure losses. Major focus is concentrated on single phase drilling fluids, which is far from accurate estimation of pressure losses for multiphase fluids, i.e., fluids including a liquid and a gas phase, at the bit. Some of these models are valid for multiphase fluids, however, they are either valid for very high gas flow rates, or developed using very strong assumptions. This study presents a mathematical model for calculating bit hydraulics for gasified drilling fluids. The theory, which is valid for both sonic (critical) and subsonic (sub-critical) regimes, is based on the solution of the general energy equation for compressible fluid flow. The model is sensitive to changes in internal energy, temperature and compressibility. In addition, the model uses &ldquo / mixture sound velocity&rdquo / approach. A computer program is developed based on the proposed mathematical model. The program calculates pressure drop through a nozzle in subsonic flow region, and suggest flow rate if the calculated pressure drop values is in the sonic flow pressure ranges. The program has been run at reasonable field data. The results of the models have been compared with the results of existing models in the literature. The results show that the pressure losses through the bit can be estimated with a variation less than 9%. Also, it has been observed that bottom hole pressure, velocity of the liquid phase and nozzle size have a strong influence on bit pressure drop.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-12T15:40:08Z No. of bitstreams: 1 DANIELA PASSOS SIMÕES DE ALMEIDA TAVARES - TESE PPGEQ 2016..pdf: 15494076 bytes, checksum: 86040371b4c9f0e560658409f7d3b95d (MD5) / Made available in DSpace on 2018-03-12T15:40:08Z (GMT). No. of bitstreams: 1 DANIELA PASSOS SIMÕES DE ALMEIDA TAVARES - TESE PPGEQ 2016..pdf: 15494076 bytes, checksum: 86040371b4c9f0e560658409f7d3b95d (MD5) Previous issue date: 2016-08-18 / Capes / O vazamento de fluidos tóxicos em tubulações submarinas devido à corrosão, erosão ou falhas na estrutura, geralmente conduzem a danos extensivos à vida marinha, saúde humana e recursos naturais. Quando um vazamento acidental ocorre, uma resposta rápida e adequada é necessária para reduzir as consequências ambientais. Logo, compreender, por exemplo, o comportamento da pluma de óleo vazado possibilita a determinação do percurso da pluma de óleo e a dispersão da mesma na correnteza marítima e, assim, propor técnicas e/ou tecnologias para eliminar ou minimizar os danos causados pelo vazamento. Neste sentido, foi realizado um estudo do comportamento da pluma e sua dispersão, adotando-se uma abordagem Euleriana-Euleriana. Foi utilizado um modelo matemático representativo da fluidodinâmica de uma pluma de óleo originada do vazamento em um riser tipo catenária. Adotou-se um escoamento bifásico (Modelo de Superfície Livre), isotérmico e turbulento (modelo k-ε padrão) para se resolver as equações de conservação de massa e momento linear utilizando ANSYS CFX® v.15. Os resultados dos campos de pressão, velocidade e fração volumétrica, além dos perfis de fração volumétrica possibilitaram a avaliação do comportamento da pluma e de sua dispersão no mar. Observou-se que a pluma atingiu a superfície marítima quando adotado altas velocidades de vazamento de óleo e baixas velocidades da correnteza marítima. Para os casos em que a densidade do óleo é maior, houve espalhamento lateral subsuperfície. Para os casos com maior velocidade do jato de óleo e menor velocidade da água do mar, na chegada do óleo à superfície observou-se que houve espalhamento horizontal a montante e a jusante do sentido de escoamento. A depender das condições de velocidade de vazamento, da correnteza marítima e da diferença de densidade percebeu-se uma tendência da pluma não atingir a superfície marítima. / The leak of toxic fluids in submarine pipes due to corrosion, erosion or failures in the structure, generally lead to extensive damage to marine life, human health and natural resources. When occurs an accidental leak, a quick and adequate response is needed to reduce the environmental consequences. Therefore, understand, for example, the behavior of leaked oil plume enables the determination of the oil plume path and the dispersion of the same in the sea current and like this propose techniques and/or technologies to eliminate or minimize the damage caused by the leak. In this sense, it was proposed a study of the behavior of plume and its dispersion, adopting an EulerianEulerian approach. It was used a representative mathematical model of the fluid dynamics of an oil plume originated from leak at riser in catenary format. It was adopted a two-phase flow (Free Surface Model), isothermal and turbulent (k-ε standard model) to solve the mass and momentum conservation equations using ANSYS CFX® v.15. The results of the pressure, velocity and volumetric fraction fields, and the volumetric fraction profiles allowed the plume behavior assessment and dispersal at sea. Also it was observed that the plume reaches the sea surface when adopted high velocities of oil leak and low velocities of sea current. For the cases in which the oil density is higher, there was lateral subsurface scattering. For the cases with higher velocity of the oil jet and lower velocity of the sea water, in the arrival of the oil to the surface it was observed that there was horizontal scattering upstream and downstream of the direction of flow. Moreover, depending on conditions of the leak velocity, of the sea current and of the density difference was noticed a tendency of the plume not reach the sea surface.

Diversas aplicações industriais envolvem escoamentos multifásicos, como é o caso das operações de produção de petróleo em águas profundas, onde partículas sólidas, como areia ou hidratos, podem estar presentes, dando origem ao escoamento sólido-líquido-gás. O escoamento no padrão golfadas é frequentemente encontrado em linhas de produção de petróleo provocado pela topografia do terreno. É de grande valia para a indústria, a compreensão da dinâmica deste tipo de escoamento para o projeto de linhas de produção de óleo e gás, assim como para o dimensionamento de separadores e equipamentos. Nesse contexto, o presente trabalho experimental caracteriza o escoamento de três fases, gás-sólidolíquido em um tubo horizontal, visando determinar o impacto das partículas sólidas sintéticas (similares aos hidratos de gás) sobre os parâmetros característicos do escoamento em golfadas (velocidade da frente da bolha, frequência de passagem da célula unitária, comprimento da bolha e do pistão). Os testes experimentais foram realizados utilizando partículas sólidas, com massa específica semelhante às partículas de hidratos de gás, dispersas na fase líquida. Partículas sintéticas modelo de polietileno de 0,5 mm de diâmetro e 938 kg/m3 de massa específica foram utilizadas como a fase sólida. Água e ar comprimido foram utilizados como fase líquida e gasosa, respectivamente. A seção de testes compreende uma tubulação de 26 mm de diâmetro interno e 9 m de comprimento. As estruturas do escoamento foram monitoradas por meio de sensores resistivos e uma câmara de alta velocidade. Diversas combinações de velocidades superficiais de líquido e gás, que garantam o padrão intermitente em golfadas, e diferentes concentrações de partículas foram aplicadas nos testes. Os sinais obtidos foram processados e apresentados através de funções densidade de probabilidade (PDF) e valores médios. Estes valores obtidos foram discutidos e comparados com o escoamento bifásico em golfadas líquido-gás para condições semelhantes. Pôde ser observado que as partículas sólidas influenciam positivamente na velocidade da frente da bolha e a frequência, e influenciam negativamente nos comprimentos do pistão e da bolha. / Multiphase flows appear during a large number of industrial operations, as in the case of oil and gas offshore production operations, where solid particles, such as sand and hydrates may occasionally be present in the flow, starting the solid-liquid-gas flow. Slug flow in ducts is a frequently observed flow regime in oil and gas transportation lines. The onset of this kind of flow is due to instabilities generated by irregular pipe topography. Understanding the hydrodynamics of the slug flow is significant in the design of crude oil production lines as well as in the project of equipment involved in oil and gas operations. The present work experimentally characterizes the gas-liquid-solid three-phase flows in a horizontal pipe. The objective here is to determine the role played by solid particles (similar to hydrates) on the characteristic parameters of slug flows, namely the bubble front velocity, unit cell frequency and bubble and liquid slug lengths. Experimental tests with solid particles (whose specific mass are similar to those of the hydrate particles) dispersed in the liquid were carried out. The test section comprised a 26 mm ID, 9 m long transparent acrylic pipe. The flow structures were monitored and measured by means of resistive sensors and a high-speed camera. Several pairs of gas and liquid superficial velocities, for which the slug flow regime was observed, at different solid particle concentration were investigated during the tests. Synthetic standard 0.5 mm diameter polyethylene particles with 938 kg/m3 density constituted the solid phase. Water and compressed air were used as the liquid and gas phase, respectively. The signals captured during the tests were processed and presented in terms of a probability density function (PDF) and averaged values. The experiments and their results are discussed and compared to the two-phase gas-liquid flows at similar conditions. It was observed that solid particles influence positively the bubble front velocity and frequency, and influence negatively the piston and bubble lengths.

[pt] Óleos brutos altamente parafínicos podem causar problemas operacionais significativos, tais como bloqueio de um oleoduto devido à precipitação e deposição de componentes de parafina durante a produção e transporte de petróleo bruto. O custo de gerenciamento da parafina é enorme e aumenta significativamente com o aumento da produção de petróleo em áreas marítimas profundas. Mas estes custos podem ser significativamente reduzidos se a deposição de parafina em dutos puder ser prevista com precisão. Nesta pesquisa, o fenômeno de deposição foi analisado numericamente. O modelo de deslizamento foi utilizado para prever o fluxo multifásico e a deposição de parafina foi determinada a partir de um modelo de convecção. Este modelo previu com precisão as taxas de deposição de escala de laboratório em regime de fluxo laminar e turbulento. A taxa de deposição de parafina apresentou uma boa concordância com os resultados do software comercial OLGA. A comparação com a produção de petróleo de um poço real foi modelado, e bons resultados foram obtidos no impacto da queda de pressão devido à redução da área seção transversal causada pela deposição de parafina progressiva na parede do tubo. Os resultados deste trabalho mostraram uma boa consistência física e um acordo razoável com os dados experimentais e de campo comparados. / [en] Highly waxy crude oils can cause significant operational problems such as blockage of a pipeline due to the precipitation and deposition of select wax components during the production and transportation of the crude oil. The cost of wax management is enormous and rapidly increasing because of increased oil production in deep sea areas. Wax management costs can be significantly reduced if wax deposition in pipeline can be accurately predicted. In this research, the wax deposition phenomenon was numerically investigated. The drift flux model was employed to predict the multiphase flow and the wax deposition was determined based on a convective model. This model accurately predicted the deposition rates for lab scale under laminar and turbulent flows. The wax deposition rate presented a good agreement with the results of commercial software OLGA. A comparison with an existing oil production well was performed, and good results were obtained in the impact in pressure drop due to cross section area reduction caused by progressive wax deposition on the pipe wall. The results of this work showed a good physical consistency and a reasonable agreement with the compared experimental and field data.

Les Champs Phlégréens, situés dans la métropole napolitaine (Italie du sud), forment l’une des plus grandes structures volcaniques au monde. Depuis 1950, ce complexe volcanique manifeste un regain d’activité, qui s’est amplifié au cours de la dernière décennie. Cette accélération s’exprime au travers d’une intensification de la sismicité, de la déformation du sol ainsi qu’une extension de la zone de dégazage. L’ensemble des récentes études s’accorde à dire que le système s’achemine actuellement vers un point critique, sans toutefois pouvoir préciser quand et où pourrait avoir lieu une éventuelle éruption. Cette difficulté à prédire l’état réel du système est principalement associée à la présence d’un système hydrothermal relativement développé. Aux Champs Phlégréens, il est en effet difficile de déconvoluer les signaux provenant du forçage magmatique de ceux résultant de la réponse hydrothermale. L’objectif de cette thèse est donc d’améliorer les connaissances actuelles du système hydrothermal superficiel du volcan de la Solfatara, lieu où se concentre actuellement la reprise d’activité. Pour cela, une approche multidisciplinaire a été menée en deux phases : l’imagerie géophysique du volcan puis la modélisation de son système hydrothermal.La tomographie haute-résolution de résistivité électrique 3-D du cratère a permis de reconnaître les principales formations géologiques et leurs connexions avec les structures et écoulements hydrothermaux. L’interprétation du modèle de résistivité électrique a été réalisée grâce à un ensemble de mesures superficielles complémentaires : flux de CO2, température, potentiel spontané, capacité d’échange cationique et pH du sol. Deux panaches à dominante liquide ont été identifiés : la mare de boue de la Fangaia et la fumerole de Pisciarelli. À la Fangaia, une étude conjointe des modèles de résistivité électrique et de vitesses du sous-sol (obtenues par l’INGV) établit la présence de forts gradients, à la frontière entre panache hydrothermal et zone de dégazage diffus. Au niveau du principal secteur fumerolien, le modèle de résistivité électrique et la localisation des sources acoustiques révèlent clairement l’anatomie d’une zone fumerolienne. Deux conduits séparés, saturés en gaz, alimentent les fumeroles de Bocca Grande et de Bocca Nuova, depuis un même réservoir de gaz situé à ~50 mètres de profondeur. L’intense dégazage diffus produit à proximité de ces fumeroles occasionne la condensation de vapeur. Le modèle de résistivité électrique met en évidence la circulation souterraine de cet important volume d’eau, canalisée à l’intérieur d’une zone fracturée.En utilisant l’ensemble de ces informations structurelles, un modèle thermodynamique des écoulements multiphasiques de la principale zone fumerolienne a été réalisé. Ce modèle reproduit fidèlement les observables des fumeroles : température, flux et rapport CO2/H2O. Il valide l’imagerie géophysique et confirme l’interaction entre la circulation d’eau de condensation et l’un des conduits fumeroliens. Ainsi, cette simulation explique, pour la première fois par un effet d’interaction superficiel, les différentes signatures géochimiques des deux fumeroles : Bocca Nuova et Bocca Grande. L’approche multidisciplinaire, employée dans cette thèse, constitue une nouvelle étape vers une meilleure connaissance des interactions hydrothermales. Celles-ci doivent être prise en compte dans l’objectif de réaliser des modélisations dynamiques précises permettant d’appréhender in fine l’état réel du système volcanique. / The Campi Flegrei caldera is located in the metropolitan area of Naples (Italy), and it is one of the largest volcanic systems on Earth. Since 1950, this volcanic complex shows significant unrest, which accelerated over the last decade with a rise in the seismic activity, ground deformation, and the extent of the degassing area. Recent studies indicate that the volcanic system is potentially moving toward a critical state, although their authors remain unable to point out when and where a possible eruption could take place. The difficulty of predicting the real volcanic state is here mainly related to the hydrothermal system. Indeed, at the Campi Flegrei, it is difficult to separate the magmatic input signal from the hydrothermal response. Hence, the aim of this thesis is to improve our knowledge on the shallow hydrothermal system of the Solfatara volcano, where most of the renewal activity takes place. A multidisciplinary approach has been performed in two steps: first a geophysical imagery of the volcano and second the modeling of its hydrothermal system.The 3-D electrical resistivity tomography of the crater allows to recognize the main geological units, and their connection with hydrothermal fluid flow features. The interpretation of the resistivity model has been realized thanks to numerous soil complementary measurements: CO2 flux, temperature, self-potential, Cation Exchange Capacity and pH. We identify two liquid-dominated plumes: the Fangaia mud pool and the Pisciarelli fumarole. In the Fangaia area, the comparison between electrical resistivity and velocity models reveals strong gradients related to a sharp transition at the border between the hydrothermal plume and the high diffuse degassing region. Combining electrical resistivity model with hydrothermal tremor sources localization reveal the anatomy of the main fumarolic area. Two separated conduits, gas-saturated, feed the two fumaroles Bocca Grande and Bocca Nuova. These conduits originate from the same gas reservoir located 60 m below the surface. The intense degassing activity, produced in the vicinity of fumaroles, creates large amounts of vapor condensation. The resistivity model reveals this condensate circulation, within a fractured area.All these results are incorporated into a multiphase flow model of the main fumarolic area. The simulation accurately reproduces the fumaroles observables: temperature, flux and CO2/H2O ratio. The model validates the geophysical imagery and confirms the interaction between Bocca Nuova fumarolic conduit and the condensate flow. Hence, this simulation explains for the first time the distinct geochemical signature of the two fumaroles due to a shallow water-interaction. The multidisciplinary approach performed in this thesis constitutes a new step toward a better understanding of hydrothermal interactions. Those phenomena have to be taken into account in order to perform dynamic modelling, and thus apprehend the real state of the volcanic system.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-11-05T12:39:57Z No. of bitstreams: 1 GENILDO RIBEIRO DO NASCIMENTO - TESE (PPGEP) 2011.pdf: 15030089 bytes, checksum: e81e7db2dc5710f5ef448ea2e4b1e612 (MD5) / Made available in DSpace on 2018-11-05T12:39:57Z (GMT). No. of bitstreams: 1 GENILDO RIBEIRO DO NASCIMENTO - TESE (PPGEP) 2011.pdf: 15030089 bytes, checksum: e81e7db2dc5710f5ef448ea2e4b1e612 (MD5) Previous issue date: 2011-08-24 / Este trabalho apresenta um estudo teórico sobre escoamento multifásico (gás-óleo pesado-água) em dutos flexíveis que tem uso em diversas aplicações da indústria petrolífera e não petrolífera. As equações governantes são baseadas no modelo multifluido Euleriano-Euleriano não-homogêneo, considerando o escoamento tridimensional em regime permanente laminar e não-isotérmico. As simulações foram efetuadas usando-se o código computacional CFX-3D. Os resultados das distribuições de velocidade, pressão, fração volumétrica e temperatura ao longo do duto são apresentadas e analisadas. Verificou-se que a curvatura do duto e a fração volumétrica das fases presentes têm forte influência na hidrodinâmica do escoamento. Fez-se uma avaliação da região onde pode ocorrer precipitação de parafina e os resultados obtidos são consistentes fisicamente e permitem um melhor conhecimento acerca do escoamento multifásico (água, óleo pesado e gás). / This work presents a theoretical study on multiphase flow (gas-heavy oil-water) in flexible pipe which is used in many applications of petroleum industry and others industries. The governing equations are based on Eulerian-Eulerian multifluid model and non-omogeneous, by considering the steady non-isothermal laminar flow. The simulations were performed using the computer code CFX-3D. Results of the velocity, pressure, volume fraction and temperature distributions along the pipeline are presented and analyzed. It was verified that the curvature of the pipe and the volumetric fraction of the phases has large influence in the hydrodynamic of flow. An evaluation of paraffin precipitation and the results are consistent physically and allow a better knowledge of multiphase flow (water, heavy oil, gas).

La conception de nouveaux moteurs impose de respecter des normes de sécurité concernant les performances d'allumage et de ré-allumage en conditions critiques. Des campagnes d'essais étant onéreuses, les industriels cherchent donc à disposer d'outils numériques fiables. Afin d'améliorer la simulation des écoulements, le caractère multicomposant du carburant doit être pris en compte. L'objectif de cette thèse est d'étudier l'influence de l'évaporation d'un brouillard de gouttes sur un écoulement réactif. Pour cela, une étude de la propagation d'une flamme laminaire 1D est réalisée à l'aide d'un code de calcul multiphysique (CEDRE). Un train continu de gouttes monodisperse est injecté, les gouttes étant mono ou bicomposant. L'influence de la dynamique d'évaporation sur la combustion est étudiée. Deux cinétiques chimiques réduites multicomposant sont comparées. La composition, le diamètre et la richesse initiale des gouttes ont un impact sur la structure de flamme, la vitesse de flamme et la composition des gaz brûlés. Ensuite, l'effet de l'évaporation est étudié en phase d'allumage pour un brouillard de gouttes polydisperses monocomposant avec un modèle de noyau d'allumage local. L’écoulement instationnaire non-réactif dans un secteur de chambre industriel (MERCATO) est calculé avec une approche LES. Le caractère instationnaire, voire périodique, de la phase dispersée est mis en évidence en certains points de l'écoulement. Les résultats, associés au modèle d'allumage et à des critères, sont utilisées pour réaliser une carte de probabilité d'allumage. Des essais de calcul d'allumage complet de la chambre sont réalisés. Les résultats indiquent une surestimation des termes sources liés à l'évaporation de la phase dispersée et à la combustion. / The design of new aircraft engines needs in particular to comply with safety standards for the performance of stabilized combustion and ignition or re-ignition under critical conditions. Experimental campaigns are expensive, so numerical tools are needed. To improve the accuracy of the models used to simulate flow, the multicomponent nature of the fuel must be taken into account, whether it is kerosene or alternative fuel. The objective of this thesis is to study the influence of a droplet mist vaporization on a reactive flow. For this, an academic study of the propagation of a 1D laminar flame is performed using a CFD code {CEDRE). A continuous stream of monodisperse droplets is injected, the droplets being mono or bicomponent. The influence of the dynamics of evaporation on combustion is particularly studied. Two reduced multicomponent chemical kinetics are compared. The composition, the diameter and the initial equivalent ratio of droplets have an impact on the structure of the flame, the flame speed and composition of the burnt gases. A local ignition kernel model is applied to study the influence ofvaporization on ignition in the case of monocomponent, polydisperse droplets. Experimental data are available for a monosector combustion chamber (MERCATO) so the non-reactive unsteady flow is simulated with a LES approach. The unsteady, sometimes periodic, nature of the dispersed phase is highlighted in some points of the flow. A ignition model is applied to instantaneous flow fields and criteria are analysed to realise an ignition probability map which validates the approach. Finally, ignition of a combustion chamber is tested. The results point out an overestimation of source terms related to the evaporation of the dispersed phase and combustion.

Le travail présenté concerne l'étude des instabilités thermo-acoustiques apparaissant dans une chambre de combustion aéronautique. Le montage expérimental permet de faire varier continument les fréquences de résonances et de passer pour une même condition d'écoulement, d'un régime de combustion stable à un régime instable. La caractérisation complète d'un cas instable comprend une mesure des conditions acoustiques aux limites du banc, une analyse du comportement des phases liquide et évaporée, de celui du dégagement de chaleur instationnaire et une mesure de la fonction de transfert de la flamme. Ces travaux ont mis en évidence trois phénomènes jouant sur l’injection cyclique de carburant liquide. Les temps caractéristiques des différents phénomènes intervenant dans le couplage thermo-acoustique et une distribution spatiale de l'indice de Rayleigh sont présentés. / The purpose of this experimental study was to further our understanding of the fuel spray behavior during combustion instability phenomena in combustion chambers. An aeronautical injection system with dual kerosene lines was mounted on the LOTAR setup, which was equipped with an adjustable exhaust length. Stability maps were generated by varying the global equivalent ratio and the fuel split parameter, for two Inner Exhaust Lengths (IEL). A non-unique multiphase flow condition was found to produce stable and unstable combustion for different IELs. Each configuration was fully characterized. Acoustic boundary conditions were measured using the 2-microphone technique. Different optical techniques were used toanalyze the unsteady behavior of the liquid phase, fuel vapor, and heat release. Moreover, two techniques were exploited to study the Flame Transfer Function using velocity measurement supstream and downstream of the injection device. Altogether, these results highlighted three atomization phenomena occurring during the cycles of thermo-acoustic instabilities. The phase-averaged analysis applied on the different measurements permitted to determine thetime scales associated with each process appearing in the thermo acoustic coupling. This cyclic injection of liquid fuel into the chamber was followed by a vapor phase increase corresponding to a wave of equivalent ratio. The delay between the two phenomena was of10°. In addition, OH* emissions showed a cyclic behavior following these waves. The delay between the wave of equivalent ratio and the unsteady heat release was approximately of 25°.Finally, spatial distribution of the Rayleigh index revealed that the inner recirculation zone contributed to sustain the combustion instability.