[pt] Neste trabalho um novo elemento de viga co-rotacionado é apresentado para a análise não-linear geométrica tridimensional, estática e dinâmica, de linhas marítimas de Materiais com Gradação Funcional (MGF). Assume-se que o módulo de elasticidade e a massa específica do material da viga variam ao longo da espessura da seção transversal tubular de acordo com uma lei de potência. Na discretização espacial das equações de equilíbrio, a linha marítima é representada por um elemento de viga de dois nós, com base nas hipóteses do modelo para vigas de Euler-Bernoulli, em que polinômios cúbicos de Hermite são utilizados na interpolação dos deslocamentos nodais e a cinemática do movimento é descrita através de grandezas referidas a um sistema coordenado local co-rotacionado. Consideram-se não linearidades geométricas envolvendo grandes deslocamentos e rotações, mas com pequenas deformações. Nas equações de movimento da linha marítima, são consideradas as seguintes influencias: do peso próprio, do empuxo, dos carregamentos hidrodinâmicos (devidos às ações de ondas, correntes e forças de massa adicional), dos deslocamentos prescritos (junto à fixação da embarcação), da ação de flutuadores e das forças de interação solo-estrutura. A integração temporal das equações de equilíbrio é realizada utilizando-se o algoritmo de discretização HHT (Hilbert-Hughes-Taylor) e a solução numérica obtida com a técnica iterativa de Newton Raphson. A metodologia numérica foi implementada e diversos exemplos são apresentados e discutidos enfatizando-se as diferenças de comportamento estrutural entre os modelos de viga com MGF e com material homogêneo. Resultados referentes a situações práticas da engenharia offshore são também tratados nos exemplos. / [en] This work presents a new co-rotational beam element formulation to model the geometric three-dimensional static and dynamic nonlinear analysis of risers of Functionally Graded Materials (FGM). The material modulus of elasticity and density of the beam are assumed to vary through the pipe cross-section thickness following a power law function. In the spatial discretization of the riser equilibrium equations, a two node beam element based on Euler-Bernoulli theory is considered, with cubic Hermitian interpolation functions used for nodal displacement interpolations and element kinematics, all referred to a co-rotation coordinate system attached to the element local frame. In the element model, geometric non-linear effects are considered, involving large displacements and rotations but small strains. The motion of the riser results from the following applied forces: self weight, buoyancy, hydrodynamic (due to maritime waves, currents and added mass inertia), prescribed displacements (at the floating platform), action of floaters and seabed-structure interactions. Step-by-step time integration of the equilibrium equations is performed with HHT (Hilbert-Hughes- Taylor) algorithm and the numerical solution is obtained using the Newton- Raphson iterative technique. The methodology has been implemented and various sample results presented, that highlight the behavior of functionally graded material beams as compared to homogeneous beams. Applications related to practical offshore engineering situations are also considered.

Les chantiers de maintenance et d’assainissement dans les centrales nucléaires nécessitent la mise en place d’enceintes ventilées autour des zones contaminées afin de limiter la propagation de la contamination à l’environnement extérieur. L’air rentre dans l’enceinte aux travers d’ouvertures sous la forme d’un écoulement directionnel, orienté de l’extérieur vers l’intérieur, assurant ainsi le confinement dynamique. En raison des opérations qui se déroulent à l’intérieur de l’enceinte et des perturbations externes, il est possible que l’écoulement de confinement dynamique aux ouvertures soit perturbé et subisse des inversions locales et instationnaires, conduisant ainsi à transporter la contamination à l’extérieur de l’enceinte. La présente étude s’intéresse aux petites ouvertures de type fentes minces rectangulaires où l’écoulement au droit de celles-ci est généralement turbulent. Les principaux objectifs de la thèse sont d’une part d’identifier les conditions aérodynamiques susceptibles de produire le phénomène de rétrodiffusion aux ouvertures, d’autre part d’évaluer la capacité des approches de modélisation de la turbulence URANS et LES à reproduire les instabilités liées à ce type d’écoulement. Il a été montré que l’apparition du phénomène de rétrodiffusion est principalement liée à la présence d’une perturbation aéraulique additionnelle, de type jet turbulent ou sillage, en compétition avec l’écoulement initial de confinement dynamique. Des expériences de traçage gazeux ont été mises en place sur une maquette expérimentale dans le but de quantifier la rétrodiffusion en fonction des différentes conditions aérauliques à l’ouverture et des caractéristiques de celle-ci. Des visualisations des écoulements à l’ouverture ont également été réalisées à l’aide d’un dispositif de tomographie laser. Enfin, l’analyse des résultats des simulations CFD a démontré que les approches de type RANS ou URANS ne permettaient pas de reproduire les instabilités de l’écoulement conduisant au phénomène de rétrodiffusion, contrairement aux simulations des grandes échelles de la turbulence (LES) qui reproduisent fidèlement les structures locales et instantanées à l’origine du phénomène.

Ce travail a pour but de comparer les approches de simulation numérique des grandes échelles explicite (LES) et implicite (ILES) pour un jet turbulent non-réactif ou réactif d’hydrogène à grande vitesse dans un co-courant d’air, typique d’un super-statoréacteur. La résolution des calculs va de 32 × 32 × 128 à 256 × 256 × 1024, à l’aide d’un schéma WENO d’ordre 5. Les LES explicites emploient les modèles sous-maille de Smagorinsky et de Fonction de Structure Sélective, associés au transport moléculaire. Les LES implicites sont réalisées avec et sans modèle de transport moléculaire, en résolvant les équations de Navier- Stokes ou d’Euler. Dans le cas non-réactif, le modèle de Smagorinsky est trop dissipatif. Le modèle de Fonction de Structure Sélective améliore les résultats, sans faire mieux que l’approche ILES quelle que soit la résolution. Dans le cas réactif, une coupure physique visqueuse est indispensable pour fixer une épaisseur à la flamme, et assurer la convergence en maillage de l’approche ILES. On montre aussi que les résultats LES/ILES sont moins sensibles aux conditions d’injection que ceux de l’approche RANS. Le premier chapitre est une introduction générale au contexte de l’étude. Au second chapitre, on rappelle les équations générales pour un écoulement réactif et on détaille les modèles thermodynamique et de transport retenus. Au troisième chapitre, les équations de la LES et les modèles sous-maille sont présentés. On examine également quelques propriétés du schéma numérique. Le chapitre 4 est consacré à la méthode numérique et au code de calcul. Enfin, on présente les cas-tests et on discute les résultats au chapitre 5. / This work is intended to compare Large Eddy Simulation and Implicit Large Eddy Simulation (LES and ILES) for a turbulent, non-reacting or reacting high speed H2 jet in co-flowing air, typical of scramjet engines. Numerical simulations are performed at resolutions ranging from 32 × 32 × 128 to 256 × 256 × 1024, using a 5th order WENO scheme. Physical LES are carried out with the Smagorinsky and the Selective Structure Function models associated to molecular diffusion. Implicit LES are performed with and without molecular diffusion, by solving either the Navier-Stokes or the Euler equations. In the nonreacting case, the Smagorinsky model is too dissipative. The Selective Structure Function leads to better results, but does not show any superiority compared to ILES, whatever the grid resolution. In the reacting case, a molecular viscous cut-off in the simulation is mandatory to set a physical width for the reaction zone in the ILES approach, hence to achieve grid-convergence. It is also found that LES/ILES are less sensitive to the inlet conditions than the RANS approach. The first chapter is an introduction to the context of this study. In the second chapter, the governing equations for multispecies reacting flows are presented, with emphasis on the thermodynamic and transport models. In the third chapter, physical LES equations and explicit sub-grid modeling strategies are detailed. Some properties of the numerical scheme are also investigated. In chapter four, the numerical scheme and some aspects of the solver are explained. Finally, non-reacting and reacting numerical experiments are presented and the results are discussed.

MOTA, Sandra Mara Brasileiro. Linfoma não-Hodgkin difuso de grandes células B : características clínicas, tratamento e prognóstico com os esquemas quimioterápicos CHOP e CHOP-Bleo. 2006. 75 f. Dissertação (Mestrado em Ciências Farmacêuticas) - Universidade Federal do Ceará. Faculdade de Farmácia, Odontologia e Enfermagem, Fortaleza, 2006. / Submitted by denise santos (denise.santos@ufc.br) on 2013-01-04T14:28:51Z No. of bitstreams: 1 2006_dis_smbmota.pdf: 287907 bytes, checksum: 7e0bc229874c243a42727335a9fd1299 (MD5) / Approved for entry into archive by Erika Fernandes(erikaleitefernandes@gmail.com) on 2013-01-23T11:37:46Z (GMT) No. of bitstreams: 1 2006_dis_smbmota.pdf: 287907 bytes, checksum: 7e0bc229874c243a42727335a9fd1299 (MD5) / Made available in DSpace on 2013-01-23T11:37:46Z (GMT). No. of bitstreams: 1 2006_dis_smbmota.pdf: 287907 bytes, checksum: 7e0bc229874c243a42727335a9fd1299 (MD5) Previous issue date: 2006 / Diffuse Large B-Cell Lymphomas (DLBCL) corresponds to 50% of non-Hodgkin’s lymphomas (LNH). Their treatment of choice is the association chemotherapy, in special the CHOP therapy (cyclophosphamide, doxorubicin, vincristine and prednisone) considered the standard treatment initial of the DLBCL. Variations of this therapy, with the CHOP-Bleo protocol (cyclophosphamide, doxorubicin, vincristine, prednisone and bleomycin) have been used with the intention of obtaining complete response rates for the patients. In Brazil, little is known about the incidence, clinical behavior, response to therapy and survival of the patients with DLBCL. This study aimed to set out the epidemiological profile of patients with diffuse large B-Cell lymphomas, who received medical care at Hospital Universitário Walter Cantídio (HUWC), outline in Ceará state, with the first attendment from January 1989 to December 2003, who the used the CHOP and/or CHOP-Bleo therapy; Evaluating the security and efficiency of the protocols proposed by analysis of the kind of therapeutical response, clinical and laboratorial outcomes of these patients. The data collection was performed from medical recording of the 31 patients analyzed. These, 21 (67,74%) were the men and 10 (32,26%) women. The average age was 45,81 ± 16,3 anos. Agriculturists represented 25,82% (8/31) of all patients. The stage III the Ann Arbor classification were the most frequent (32,26%), but only 45% of the patients had B symptoms. The values of lactate dehydrogenises (LDH) enzyme were elevated in 49% of the patients at diagnosis, but in 16% of the patients these values at diagnosis were unknown. As much as the IPI, 71% were classified as an IPI low and intermediate risk, 13% as an IPI intermediate-high risk, none of the study patients showed as an IPI high risk and 16% there is not possible the classification to establish due to the data is unknown. As much as the chemotherapy protocols used, 58% (18/31) of the patients was received CHOP chemotherapy, 36% (11/31) CHOP-Bleo chemotherapy and 6% (2/31) received CHOP associated with CHOP-Bleo chemotherapy. Among the patients who used CHOP chemotherapy, 78% was achieving complete response (CR), 17% was achieving relapse of the disease and only 5% were the death. In the group who used CHOP-Bleo chemotherapy, 63% was achieving RC, 18% was achieving relapse of the disease and 19% died. The 2 patients who used CHOP and CHOP-Bleo chemotherapy were achieving relapse of the disease. The values of the LDH after chemotherapy showed decreased in patients with RC as much as the relapsed patients. We verified that the overall survival (OS) and disease-free survival (DFS) were not influenced by the clinic stage and initial values of the LDH patients. The logistic regression did not show statistical differences when the complete response was analyzed comparing to outcomes the studied variables after QT, except for the proportion of reduction of LDH levels and response to the treatment. The results stress the security and efficiency of the protocols CHOP e CHOP-Bleo in our study population. The data obtained also the need epidemiological studies in different DLBCL populations for the security in the choice chemotherapy, well as standardized the classification and description of the DLBCL and prognoses factures by pathologists and oncologists. / O linfoma difuso de grandes células B (LDGCB) corresponde a 50 % dos casos de linfoma não-Hodgkin (LNH). Seu tratamento de escolha é a quimioterapia de associação, em especial o esquema CHOP (ciclofosfamida, doxorrubicina, vincristina e prednisona), considerado o tratamento inicial padrão dos LDGCB. Variações deste esquema, como o protocolo CHOP-Bleo (ciclofosfamida, doxorrubicina, vincristina, prednisona e bleomicina) tem sido utilizadas com a intenção de se obter maiores taxas de remissão completa pelos pacientes. No Brasil, pouco se conhece a respeito da incidência, do comportamento clínico, da resposta às terapêuticas utilizadas e da sobrevida de pacientes com LDGCB. Este estudo teve como objetivos traçar o perfil epidemiológico dos pacientes portadores de linfoma difuso de grandes células B, atendidos no Hospital Universitário Walter Cantídio (HUWC), com data de primeiro atendimento de janeiro de 1989 a dezembro de 2003, e que fizeram uso dos esquemas quimioterápicos CHOP e/ou CHOP-Bleo; avaliar a eficácia e segurança terapêutica dos esquemas propostos através da análise do tipo de resposta terapêutica, achados clínicos e laboratoriais destes pacientes. A coleta dos dados foi realizada a partir dos prontuários médicos dos 31 pacientes analisados. Destes, 21 (67,74%) eram do sexo masculino e 10 (32,26%) do feminino, com idade média de 45,81 ± 16,3 anos. A ocupação trabalhador agrícola representou 25,82% (8/31). O estádio III da classificação de Ann Arbor foi o mais freqüente (32,26%), mas apenas 45% dos pacientes apresentaram sintomas B. A lactato desidrogenase (LDH) sérica de 49% dos pacientes encontrava-se elevada à época do diagnóstico, sendo que outros 16% dos pacientes não apresentavam resultado desta enzima em seus prontuários. Quanto ao IPI, 71% foram classificados como de risco baixo e intermediário, 13% de alto risco intermediário, nenhum dos pacientes do estudo apresentou IPI compatível com de alto risco e em 16% dos pacientes não foi possível estabelecer a classificação devido à ausência de dados nos prontuários. Quanto à utilização dos protocolos quimioterápicos, 58% (18/31) dos pacientes fizeram uso do esquema CHOP, 36% (11/31) utilizaram CHOP-Bleo e 6% (2/31) utilizaram os dois esquemas quimioterápicos. Entre os pacientes que utilizaram o esquema CHOP, 78% atingiram a remissão completa (RC), 17% apresentaram recidiva da doença e apenas 5 % foram a óbito. No grupo que utilizou o esquema CHOP-Bleo, 63% atingiram a RC, 18% apresentaram recidiva da doença e 19% foram a óbito. Os 2 pacientes que utilizaram os dois esquemas como tratamento apresentaram recidiva da doença. Os valores de LDH dos pacientes após a quimioterapia apresentam-se reduzidos tanto em pacientes que atingiram a remissão completa como naqueles que tiveram recidiva. Verificamos que a sobrevida global (SG) e a sobrevida livre de doença (SLD) não foram influenciadas pelo estádio clínico e LDH inicial dos pacientes. A regressão logística não mostrou significância estatística quando analisou a remissão completa dos pacientes a partir dos resultados das variáveis em estudo pós QT, com exceção da proporção de redução da LDH e a resposta ao tratamento. Os resultados mostraram a eficácia e segurança dos esquemas terapêuticos CHOP e CHOP-Bleo em nossa população de estudo. Os resultados demonstram ainda que se faz necessário o estudo epidemiológico de diferentes populações com LDGCB para que haja segurança na escolha de esquemas quimioterápicos, bem como a uniformidade em descrever e classificar os linfomas e os seus fatores prognóstico por parte dos patologistas e oncologistas.

WIEGAND, Mario Cesar. Proposta metodológica para estimativa da produção de sedimentos em grandes bacias hidrográficas: estudo de caso Alto Jaguaribe, CE. 2009. 109 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2009. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-24T19:17:44Z No. of bitstreams: 1 2009_dis_mcwiegand.pdf: 10173855 bytes, checksum: 4bf39f0c74e0ccbca5361594889230d0 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:20:14Z (GMT) No. of bitstreams: 1 2009_dis_mcwiegand.pdf: 10173855 bytes, checksum: 4bf39f0c74e0ccbca5361594889230d0 (MD5) / Made available in DSpace on 2016-07-21T20:20:14Z (GMT). No. of bitstreams: 1 2009_dis_mcwiegand.pdf: 10173855 bytes, checksum: 4bf39f0c74e0ccbca5361594889230d0 (MD5) Previous issue date: 2009 / Estimation of sediment yield in large river basins has great importance for the analysis and monitoring of water availability and, consequently, for water resources management. However, there are several difficulties related to such estimation. Thus, the scope of this study was to propose a methodology to estimate sediment yield in large river basins with a large number of dams. The study basin is located within the Upper Jaguaribe basin and presents an area, obtained by SRTM data, of 20,670 km². The sediment yield estimation was based on a suspended sediment rating-curve, obtained by measurements of liquid and solid discharges at the basin outlet. The bedload was estimated using the model of Einstein and Brown. Also, the estimation of sediment retention in reservoirs located upstream the basin outlet was carried out. They were classified as small dams (< 50 hm³), which were grouped into five classes according to their storage capacity, and strategic dams (> 50 hm³). Note that sediment yield was obtained for a 25-years period (1984-2008). The results obtained for total sediment yield within the basin was about 450 t.km-².year-1. From this total, about 130 t.km-².year-1 reach the basin outlet, of which 79% correspond to suspended sediment and 21% is bedload. On the other hand, approximately 320 t.km-².year-1 are retained in the surface reservoirs: 91% are trapped in small reservoirs and 9% are trapped in the large dams of the basin. It can be concluded that the results obtained in this study for the total sediment yield in a large river basin is in agreement to that obtained by other authors in South America. It should also be pointed out that the small dams play an important role in the region, not only in relation to the accumulation of water, but also to the retention of sediment generated in the basin. Such retention prevents that the sediment reaches the strategic dams (Orós, for instance), reducing their sedimentation rates and thus, minimizing the impact of sedimentation on overall water availability in the basin. / A estimativa da produção de sedimentos em grandes bacias hidrográficas possui vasta importância para a análise e o monitoramento da disponibilidade hídrica e, por consequência, para a gestão dos recursos hídricos. Todavia, vários são os óbices relacionados a tal estimativa. Desta forma, o escopo geral deste estudo foi propor uma metodologia para estimar a produção de sedimentos em grandes bacias hidrográficas com número elevado de açudes. A bacia estudada encontra-se inserida na bacia do Alto Jaguaribe e apresentou uma área, obtida através do SRTM, de 20.670 km². A estimativa da produção de sedimento foi realizada com base na curva-chave de sedimento em suspensão, obtida através de medições de descargas líquidas e sólidas no exutório da bacia. A carga de sedimento de leito foi estimada aplicando-se o modelo Einstein e Brown. Procedeu-se, ainda, a estimativa do total de sedimento retido em reservatórios a montante do exutório da bacia monitorada. Estes foram classificados em pequenos açudes (<50 hm³), os quais foram agrupados em cinco classes de acordo com sua capacidade total de acumulação, e açudes estratégicos (>50 hm³). Salienta-se que a produção de sedimento foi obtida para uma série histórica de 25 anos (1984-2008). O resultado encontrado para a produção de sedimento total dentro da bacia foi da ordem de 450 t.km2.ano1. Desse total, cerca de 130 t.km-2.ano-1 passam pelo exutório da bacia, dos quais 79% correspondem a sedimento em suspensão e 21% a sedimento de leito. Por sua vez, 320 t.km-2.ano-1 ficam retidos nos reservatórios, sendo que 91% ficam presos nos pequenos reservatórios e 9% ficam presos nos grandes açudes da bacia. Conclui-se, desta forma, que o resultado encontrado neste estudo para a produção total de sedimento em grandes bacias aproxima-se do obtido por outros autores para a América do Sul. Ressalta-se, ainda, que a pequena açudagem exerce um papel de grande relevância na região, não somente em relação ao acúmulo de água para dessedentação e irrigação, mas também, quanto à retenção de sedimento erodido na bacia. Tal retenção evita que o sedimento chegue aos açudes estratégicos (Orós, por exemplo) diminuindo sua taxa de assoreamento e, portanto, minimizando a redução da disponibilidade hídrica na bacia.

Les élastomères présentent une diversité d’utilisation et des caractéristiques mécaniques spécifiques (grandes déformations, comportement dissipatif, ...) qui en font une famille de matériaux très utilisés dans l’industrie. Lors de leur fonctionnement, les pièces réelles subissent des sollicitations complexes. Comprendre les phénomènes induits par la fatigue multiaxiale constitue ainsi un enjeu important dans la phase de conception industrielle. Le matériau utilisé au cours de cette étude est un polychloroprène (CR), fourni par la société Hutchinson et présent dans les poulies découpleuses. Celui-ci possède une réponse dissipative en grandes déformations. Son comportement est modélisé à partir de lois de comportements viscohyperélastiques suivant deux approches : une méthode analytique impliquant un calcul simple en un point d’un cylindre et l’autre utilisant un calcul éléments finis implémenté dans ANSYS. Une campagne expérimentale en fatigue multiaxiale est alors réalisée, en traction-torsion afin de tester l’énergie dissipée comme critère de fatigue multiaxial. Celui-ci présente des résultats intéressants. Des diagramme de Haigh ont été établis afin de mettre en évidence le phénomène de cristallisation. Des analyses post-mortem ont été menés avec un microscope électronique à balayage et expose des spécificités morphologiques liées à la sollicitation vue par le matériau. / Due to their interesting mechanical behavior (large strain, dissipative behavior ...) and their diversity, elastomers are more and more used in industry. In service conditions, rubber components are subjected to complex loadings. Therefore, understanding phenomena induced by multiaxial fatigue constitutes an important issue in the industrial conception’s step. The material used in this work is a polychloroprene rubber, provided by Huchinson society and dedicated to silent-block’s applications. This elastomer possess a dissipative component at large strains. This behavior is determined following two approaches : an analytic method, implying a simple calculation at a local point of a cylinder and a finite elements analysis implemented with ANSYS software. An experimental investigation in multiaxial fatigue is then realized to test the dissipated energy density as a multiaxial fatigue criterion. This parameter obtained interesting results. Haigh diagrams has been built to point out crystallization phenomenon. Post-mortem analyses has been carried out with a scanning electronic microscope and exposes morphological specificities related to the material’s sollicitation.

L’objet de cette thèse est de modéliser et de simuler des écoulements turbulents diphasiques incompressibles à phases non miscibles. La modélisation et la simulation de ce type d’écoulements sont traitées dans le cadre des méthodes de Simulation des Grandes Echelles (SGE) ou Large Eddy Simulation (LES) en anglais qui consistent à calculer directement les plus grandes structures de l’écoulement et à modéliser les plus petites. Ces méthodes adaptées aux écoulements turbulents monophasiques sont étendues au cadre des écoulements turbulents diphasiques. Pour cela, elles sont couplées avec une méthode eulérienne de type ’ Volume Of Fluid’ (VOF) spécifique au caractère diphasique de l’écoulement. La pertinence du couplage entre les modélisations SGE et VOF est testée sur la configuration industrielle proposée par le CEA-CESTA: l’impact d’un jet rond turbulent sur une surface libre eau/air dans une cavité. Des mesures expérimentales de vitesse (Particle Image Velocimetry PIV) réalisées au CEA-CESTA sont disponibles pour valider les résultats numériques issus des simulations. / The scope of this dissertation is to model and simulate non-miscible two-phase turbulent and incompressible flows. The modeling and the simulation of this kind of flows are carried out in the framework of the Large Eddy Simulation (LES) which consists in calculating directly the largest structures of the flow and in modeling the finest ones. These numerical methods, applied usually to the simulation of single-phase turbulent flows, are extended to the simulation of two-phase turbulent flows in this work. Hence, the LES methods are coupled with an Eulerian ’Volume of Fluid’ (VOF) approach which is particularly adapted to interfacial flows. The relevance of this numerical coupling bewtween LES and VOF methods is validated in the following industrial configuration of the CEA-CESTA: the impact of a turbulent round jet on a free water/air surface in a cavity. Some experimental velocity measurements (Particle Image Velocimetry PIV), carried out at the CEA-CESTA, are available to validate the numerical results.

Le moteur à allumage commandé downsizé, couplé à une stratégie d’injection directe, est l’une des solutions privilégiées par les constructeurs automobiles afin de réduire les émissions polluantes et d’augmenter le rendement. Toutefois, l’augmentation de la pression d’injection visant à favoriser l’atomisation du spray et donc l’homogénéité du mélange peut engendrer une forte interaction entre le spray et les parois de la chambre de combustion. Cette interaction est à l’origine d’hétérogénéités locales susceptibles d’altérer la combustion. Du fait de son caractère instationnaire, l’interaction spray/paroi (formation et évaporation d’un film liquide) et plus généralement la préparation du mélange en moteur à injection directe essence sont des phénomènes difficiles à analyser expérimentalement. En effet, un moteur muni d’accès optiques ne peut pas fonctionner dans les conditions thermodynamiques réelles (pression, température...). Dans ce contexte, la modélisation et plus particulièrement la Simulation aux Grandes Echelles (“Large Eddy Simulation” LES) est un moyen d’analyse complémentaire et indispensable. L’objectif de cette thèse est de développer les modèles physiques nécessaires à la description de la phase liquide avec une approche Euler-Lagrange pour la simulation dans les moteurs à piston. Dans un premier temps, une modélisation des caractéristiques physiques du spray en sortie d’injecteur, nommée GDI, est proposée et validée par comparaison avec des mesures expérimentales. Les résultats montrent la capacité du modèle GDI à reproduire la dynamique générale d’un spray pour deux types d’injecteurs multi-trous. Dans un deuxième temps, deux modèles sont développés pour traiter respectivement l’interaction entre le spray et les parois et l’évaporation du film liquide. Les premières validations de ces modèles sont faites sur des expériences académiques dédiées, permettant des comparaisons précises avec les mesures. Finalement deux configurations moteur sont simulées. La première, sans combustion, permet d’évaluer l’impact d’une modélisation fine de l’interaction spray/paroi par rapport à une approche simplifiée. Les résultats montrent que la prise en compte de la formation et de l’évaporation du film liquide modifie significativement la formation du mélange, notamment le champ de richesse au Point Mort Haut. La seconde est utilisée pour analyser l’impact de la phase liquide sur le mélange et la combustion. Ces calculs sont comparés à des calculs réalisés sans injection liquide et à des mesures expérimentales. Les résultats mettent en évidence que les stratifications de richesse et de température, causées par l’évaporation du liquide, ont un effet de plissement sur la flamme et diminuent sa vitesse de propagation. / Downsized spark ignition engines coupled with a direct injection strategy, are more and more attractive for car manufacturers in order to reduce pollutant emissions and increase efficiency. However, the high pressure levels used to promote spray atomization and consequently mixing can generate a strong interaction between the spray and the combustion chamber walls. The combustion process may be affected by local heterogeneities caused by this interaction. Spray/walls interaction (formation and evaporation of the liquid film) and mixture preparation are unsteady phenomena, explaining why their experimental studies are limited. In fact, it is difficult to reproduce the thermodynamic conditions (pressure, temperature...) representative of an engine with optical accesses. In this context, numerical simulation, and in particular Large Eddy Simulation (LES) is a complementary mean of analysis. This work aims at developing the necessary models for the two-phase combustion simulation for engines, using an Euler-Lagrange approach. First, a modeling of the spray physics downstream to the injector exit is proposed and validated by comparison with experimental data. Second, two models are proposed and implemented to adress respectively the spray/wall interaction and the liquid film evaporation. These models are first validated on dedicated academics experiments, allowing an accurate comparison with experimental data. Then, two engine configurations are simulated. The first one, without combustion, allows the evaluation of an accurate spray/wall interaction modeling in comparison with a simplified approach. Results show that accounting for the formation and evaporation of the liquid film has a significant impact on the fuel/air mixing, especially on the equivalence ratio distribution at the Top Dead Center. The second one is used to analyze the impact of liquid on the mixing and the combustion. The simulations are compared to experiments data and to simulations assuming a perfect gaseous mixing (without liquid injection). Results show that the temperature and equivalence ratio heterogeneities, created by the liquid evaporation, have a wrinkling effect on the flame and reduce its propagation speed.

Dans un contexte d'amélioration des moteurs aéronautiques en termes de consommation et de pollution, les simulations numériques apparaissent comme un outil intéressant pour mieux comprendre et modéliser les phénomènes turbulents qui se produisent dans les turbomachines. La simulation aux grandes échelles (SGE) d’un étage de turbomachine à des conditions réalistes (nombre de Mach, nombre de Reynolds…) reste toutefois hors de portée dans le cadre industriel. La méthode chorochronique, aujourd’hui largement utilisée pour les calculs URANS, permet de réduire le coût des simulations numériques, mais elle implique de stocker le signal aux frontières du domaine pendant une période complète de l’écoulement. Le stockage direct de l’information étant exclu étant donné la taille des maillages et les pas de temps mis en jeu, la solution la plus courante actuellement est de décomposer le signal sous la forme de séries de Fourier. Cette solution ne retient du signal qu’une fréquence fondamentale (la fréquence de passage de la roue opposée) et un nombre limité d’harmoniques. Dans le cadre d’une SGE, elle implique donc une grande perte d’énergie, et le filtrage des phénomènes décorrélés de la vitesse de rotation comme par exemple un lâcher tourbillonnaire. Le remplacement de la décomposition en séries de Fourier par une décomposition aux valeurs propres (POD pour Proper Orthogonal Decomposition) permet de stocker le signal aux interfaces sans faire d’hypothèse sur les fréquences contenues dans le signal et donc de réduire la perte d’énergie liée à l’utilisation d’un modèle réduit. La compression s’effectue en supprimant les plus petites valeurs singulières et les vecteurs associés. Cette nouvelle méthode est validée sur la simulation URANS d'étages de turbomachines et comparée aux conditions classiques utilisant les séries de Fourier et à des calculs de références contenant plusieurs aubes par roue. Elle est ensuite appliquée à la simulation aux grandes échelles de l'écoulement d'un cylindre. Les erreurs causées par l'hypothèse chorochronique et par la compression sont séparées et on montre que l'utilisation de la POD permet de réduire de moitié le filtrage des fluctuations de vitesses par rapport aux séries de Fourier pour un même taux de compression. Enfin, la simulation aux grandes échelles d'un étage de turbomachine avec des conditions chorochroniques POD est réalisée afin de valider la méthode dans le cadre d'une configuration industrielle. / The more and more restrictive standards in terms of fuel consumption and pollution for aircraft engines lead to a constant improvement of their design. Numerical simulations appear as an interesting tool for a better understanding and modeling of the turbulent phenomena which occur in turbomachinery. The large-eddy simulation (LES) of a turbomachinery stage at realistic conditions (Mach number, Reynolds number...) remains out of reach for industrial congurations. The phase-lagged method, widely used for unsteady Reynolds-averaged Navier--Stockes (URANS) calculations, is a good candidate to reduce the computational cost. However, it needs to store the signal at all the boundaries over a full passage of the opposite blade. A direct storage of the information being excluded given the size of the mesh grid and timesteps involved, the most used solution currently is to decompose the signal into Fourier series. This solution retains the fundamental frequency of the signal (the opposite blade passage frequency) and a limited number of harmonics. In the frame of a LES, as the spectra are broadband, it implies a loss of energy. Replacing the Fourier series decomposition by a proper orthogonal decomposition (POD) allows the storage of the signal at the interfaces without making any assumptions on the frequency content of the signal, and helps to reduce the loss of energy caused by the phase lagged method. The compression is done by removing the smallest singular values and the associated vectors. This new method is first validated on the URANS simulations of turbomachinery stages and compared with Fourier series-based conditions and references calculations with multiple blades per row. It is then applied to the large eddy simulation of the flow around a cylinder. The error caused by the phase-lagged assumption and compression are separated and it is showed that the use of the POD allows to halve the filtering of the velocity fluctuations with respect to the Fourier series, for a given compression rate. Finally, the large eddy simulation of a compressor stage with POD phase-lagged conditions is carried out to validate the method for realistic turbomachinery configurations.

Dans le contexte aéronautique, cette thèse, financée par Safran Helicopter Engine, s’intéresse à l’application de l’approche Simulations aux Grandes Échelles (SGE) pour les systèmes de refroidissement de turbine. Le système de refroidissement industriel complexe est divisé en cas académiques plus simples donnant accès à des caractérisations expérimentales de la dynamique et de la thermique. Le jet impactant est traité en tant que système interne et l’écoulement de protection au bord de fuite en tant que système externe. Après une brève introduction du contexte lié au refroidissement de turbine et des objectifs scientifiques, ce manuscrit est divisé en 3 parties. La 1ère partie traite d’un écoulement de jet impactant sur plaque plane représentatif de l’impact à mi-corde. Elle se concentre sur la validation et la qualification des outils et modèles ainsi que sur l’analyse physique de l’écoulement. Les différentes instationarités de l’écoulement sont reliées à la thermique de paroi à l’aide de diagnostics statistiques et d’analyses modales. La 2ème partie s’intéresse à l’impact sur paroi concave représentatif de l’impact au bord d’attaque. Cette étude se concentre principalement sur la caractérisation de l’effet de courbure pour le jet impactant. Contrairement, au consensus actuel sur l’effet de courbure, la réduction des transferts thermiques est observée pour le cas d’étude de cette thèse. Au vu de ces résultats, une discussion est proposée pour tenter d’expliquer cet écart. Finalement, la 3ème partie de ce manuscrit contient une application de la SGE à un système de protection du bord de fuite par film isolant. Dans ce dispositif, des effets de groupe sont mis en évidence. L’impact des choix de modélisation tels que l’hypothèse de périodicité dans la direction de l’envergure est alors évalué. Il est montré que cette hypothèse de périodicité influe sur la prédiction locale de l’efficacité en forçant l’écoulement. En revanche, la prédiction de l’efficacité globale du système de protection n’est pas impactée. / This PhD thesis, funded by Safran Helicopter Engines, focuses on the application of the Large Eddy Simulation (LES) formalism to cooling systems present in high pressure turbine. The complex industrial problem is simplified into academic test cases for which experimental data are available for the validation process. The manuscript is divided into 3 parts dealing respectively with the impinging jet system on flat and concave plates and with the film cooling at the trailing edge equipped with a cutback on the pressure side. The 1st part deals with a jet impinging on a flat plate representing the impingement at mid-chord. This part focuses on the validation and qualification of the tools and models as well as on the physical analysis of the flow. The unsteadiness present in such an impinging jet flow are linked to the thermal behavior of the wall through the use of statistical analysis and modal decomposition of the flow field. The 2nd part is dedicated to the study of a jet impinging on a concave surface. This study aims at characterizing the effect of curvature for an impinging jet flow. The results found in this study disagreed with the current consensus attributing heat transfer enhancement on concave surface to Gortler instability. Hence, a discussion is proposed in an attempt to explain this discrepancy. Finally, the 3rd part reports an LES of the film cooling at the trailing edge. Group effects, due to the presence of internal ribs, are highlighted for the configuration studied here. These simulations use a spatial periodicity assumption to reduce the size of the computational domain. It is shown that this specific assumption is not suited as it forces the flow and modifies the group effect. The local results, in terms of adiabatic effectiveness, are found to be sensitive to such a forcing. However, the global behavior of the effectiveness is not impacted by this periodic boundary condition.