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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Combined Experimental and Numerical Study of Active Thermal Control of Battery Modules

He, Fan 16 April 2015 (has links)
Lithium ion (Li-ion) batteries have been identified as a promising solution to meet the increasing demands for alternative energy in electric vehicles (EVs) and hybrid electric vehicle (HEVs). This work describes experimental and numerical study of thermal management of battery module consisting of cylindrical Li-ion cells, with an emphasis on the use of active control to achieve optimal cooling performance with minimal parasitic power consumption. The major contribution from this work is the first experimental demonstration (based on our review of archival journal and conference literature) and the corresponding analysis of active thermal control of battery modules. The results suggest that the active control strategy, when combined with reciprocating cooling flow, can reduce the parasitic energy consumption and cooling flow amount substantially. Compared with results using passive control with unidirectional cooling flow, the parasitic energy consumption was reduced by about 80%. This contribution was achieved in three steps, which was detailed in this dissertation in chapters 2, 3, and 4, respectively. In the first step, an experimental facility and a corresponding CFD model were developed to capture the thermal behavior of multiple battery cells. Based on the experimental and CFD results, a reduced-order model (ROM) was then developed for active monitoring and control purposes. In the second step, the ROM was parameterized and an observer-based control strategy was developed to control the core temperature of battery cells. Finally, based on the experimental facility and the ROM model, the active control of a battery module was demonstrated. Each of these steps represents an important facet of the thermal management problem, and it is expected that the results and specifics documented in this dissertation lay the groundwork to facilitate further study. / Ph. D.
32

Modèle hybride incertain pour le calcul de réponse en fonctionnement d'un alternateur / Uncertain hybrid model in structural dynamics : application to alternator

Kuczkowiak, Antoine 12 November 2014 (has links)
Le comportement dynamique de structures complexes, comme les alternateurs, doit être maîtrisé afin d’en garantir un fonctionnement fiable. Cependant, la modélisation comporte de nombreuses incertitudes rendant délicates la prédiction du comportement vibratoire. Ces travaux de recherche ont pour objectif de fournir des outils d’aide à la décision afin de faciliter la prise de décision rapide suite au redémarrage d’alternateurs. Basé sur la théorie info-gap, un premier outil d’aide à la décision est proposé : il a pour objectif d’évaluer la robustesse de réponses dynamiques vis-à-vis d’un modèle modal incertain. Nous avons également étudié comment de l’information nouvelle peut être intégrée au modèle d’incertitude pour améliorer sa représentativité à la réalité.Une expansion par l’erreur en relation de comportement étendue de modes propres identifiés permet ensuite d’enrichir la représentativité du modèle numérique fournissant ainsi un modèle qualifié d’hybride et permettant d’évaluer les niveaux de réponse. Comme la modélisation comporte de nombreuses méconnaissances, nous avons proposé le procédé d’expansion robuste dont l’objectif est d’obtenir des vecteurs étendus robustes. En présence de méconnaissances sévères, nous montrons enfin qu’il est préférable de calibrer un modèle en maximisant la robustesse vis-à-vis des incertitudes plutôt qu’en maximisant uniquement la fidélité vis-à-vis des données. Couplée à des techniques de réduction de modèle et de construction de méta modèles,nous appliquons cette démarche à une structure de complexité industrielle représentative du contexte industriel. / The complex structural dynamic behavior of alternator must be well understood in order to insuretheir reliable and safe operation. The numerical model is however difficult to construct mainlydue to the presence of a high level of uncertainty. The objective of this work is to providedecision support tools in order to assess the vibratory levels in operation before to restart thealternator. Based on info-gap theory, a first decision support tool is proposed: the objective hereis to assess the robustness of the dynamical response to the uncertain modal model. Based on realdata, the calibration of an info-gap model of uncertainty is also proposed in order to enhance itsfidelity to reality. Then, the extended constitutive relation error is used to expand identified modeshapes which are used to assess the vibratory levels. The robust expansion process is proposed inorder to obtain robust expanded mode shapes to parametric uncertainties. In presence of lack-ofknowledge,the trade-off between fidelity-to-data and robustness-to-uncertainties which expressesthat robustness improves as fidelity deteriorates is emphasized on an industrial structure by usingboth reduced order model and surrogate model techniques.
33

Análise dinâmica não linear bidimensional de risers verticais. / Nonlinear dynamic analysis of bidimensional vertical risers.

Yamao, Michele 10 May 2013 (has links)
Na última década foram descobertas jazidas de petróleo e gás em águas profundas ao longo da costa sudeste do Brasil, o que tem levado à reavaliação de conceitos e técnicas até então utilizados para sua exploração em pequenas profundidades. Parâmetros que anteriormente eram supostamente não críticos passaram a ser relevantes no dimensionamento estrutural dos risers. Efetivamente, a descoberta de novas jazidas na Bacia de Santos incentivou o desenvolvimento de pesquisas nesta área, no Brasil e no mundo. Os depósitos de petróleo e gás encontrados abaixo da camada de sal (daí serem referidas por pré-sal) ocorrem em áreas com lâmina dágua de mais de 2.000 metros, requerendo novas tecnologias para viabilizar sua extração. Os risers de produção nada mais são do que tubulações que levam petróleo e gás do fundo do oceano para a superfície. Nas suas diversas configurações geométricas (vertical, em catenária, lazy wave, entre outros), são elementos estruturais extremamente esbeltos, que devem suportar carregamentos dinâmicos oriundos da correnteza marítima em grande profundidade, ondas de superfície, escoamento interno e deslocamentos impostos, atendendo a exigentes critérios de projeto. O riser vertical será o foco deste trabalho, no qual se pretende utilizar modelos matemáticos com poucos graus de liberdade, denominados modelos de ordem reduzida (MOR), mas com adequada capacidade de representação qualitativa e quantitativa da resposta estrutural, fazendo uso de modos não lineares como funções de projeção, dentro do método de Galerkin não linear. Os modos não lineares, intensivamente estudados no Grupo de Pesquisa Dinâmica, Estabilidade e Controle de Sistemas Estruturais da Escola Politécnica da USP, por conterem intrinsecamente informações de harmônicos de ordem superior, são capazes de, em menor número do que os modos lineares utilizados no método da superposição modal clássico, descreverem acuradamente a resposta do sistema não linear. Serão utilizados procedimentos baseados tanto no método das variedades invariantes, quanto no método das múltiplas escalas, em modelos analíticos. Para a redução de graus de liberdade, será utilizado o método de projeção que se baseia na imposição da igualdade entre os trabalhos virtuais dos modelos de alta e baixa hierarquia (MOR), de sorte que o sistema sob carregamento dinâmico possa ser estudado em espaço de fase de baixa dimensão. A presente pesquisa, além dos desafios acadêmicos inerentes ao tema, apresenta evidente relevância econômica e estratégica para o País. / In the last decade, deposits of oil and gas under deep waters were discovered along the Brazilian Southeast coast, which led to reassessment of concepts and techniques previously used for their exploitation under shallow waters. Parameters that were not previously considered to be critical became relevant in the structural design of the risers. Indeed, the discovery of new deposits in the so-called Santos Basin encouraged the development of research in this area in Brazil and worldwide. The oil and gas deposits found in the pre-salt layer occur in waters deeper than 2,000 meters, requiring new technologies to facilitate their extraction. The risers of production are nothing more than pipes that carry oil and gas from the ocean to the surface. In its various geometric configurations (vertical, catenary, lazy waves, etc.), they are extremely slender structural elements, which must withstand dynamic loads from deep currents, surface waves, internal flow and imposed motions, observing the strict design criteria regarding ultimate and service limit states. The vertical riser will be the focus of this work, which uses mathematical models with few degrees of freedom, known as reduced-order models (ROM), but with adequate capacity to represent the structural response both qualitatively and quantitatively, using non-linear modes as projection functions within the non-linear Galerkin method. The non-linear modes were intensively studied in the research group \"Dynamics, Stability and Control of Structural Systems\" at the Escola Politécnica of USP. Because they contain information of higher-order harmonics, they are able to accurately describe the response of the nonlinear system, using a smaller number of modes than the linear modes used in the classical modal superposition method. Procedures based on the method of invariant manifold and the method of multiple scales alike will be applied to analytical continuum models (with infinite number of degrees of freedom). For the reduction of degrees of freedom, a method based on the identification of the virtual works in both the high-hierarchy and the ROM will be used, so that the system under dynamic loading can be studied in a low-dimension phase space. 13 This research, in addition to academic challenges inherent to the subject has obvious economic and strategic importance for the country.
34

POD Approach for Aeroelastic Updating / Approche POD pour le Recalage du Modele Aeroelastique

Vetrano, Fabio 17 December 2014 (has links)
Bien que les méthodes de calcul peuvent donner de bons résultats, ils ne sont généralement pas en accord avec exactement les données d'essais en vol en raison des incertitudes dans les modelé de calcul de structure et aérodynamiques. Une méthode efficace est nécessaire pour la mise à jour des modelé aeroelastiques en utilisant les données d'essais en vol, les données d'essais de vibration au sol ( GVT ) et les données de soufflerie. Tout d'abord tous les développements ont été valides sur une section de l'aile 2D et sur un modèle 3D simple et après l'approche POD a été applique= a une configuration industrielle (modèle de soufflerie aile-fuselage et modèle d' avions complète). / Although computational methods can provide good results, they usually do not agree exactly with the flight test data due to uncertainties in structural and aerodynamic computational models. An effective method is required for updating computational aeroelastic models using the flight test data along with Ground Vibration Test (GVT) data and wind tunnel data. Firstly all developments have been validated on a 2D wing section and on a simple 3D model and after the POD approach has been applied to an industrial configuration (wing-fuselage wind tunnel model and complete aircraft model).
35

Développement d’algorithmes de réduction de modèles pour l’optimisation du procédé de placement de fibres robotisé / Reduced order model algorithms for Automated Tape Placement optimisation

Bur, Nicolas 08 April 2015 (has links)
La réalisation par des procédés robotisés de pièces composites à destination, notamment, de l’aéronautique vise à en augmenter la productivité. Cependant le Placement de Fibres Robotisé (PFR) est encore en phase de maturation et requiert de nombreux développements, en particulier dans le cas des composites à matrice thermoplastique ou à fibre sèche. Dans cette thèse, nous proposons différents outils qui permettent in fine de déterminer à l’avance la meilleure puissance de chauffe pour la mise en œuvre de ces composites. La difficulté réside dans le fait que cette puissance dépend de nombreux paramètres, non seulement au niveau de la matière utilisée (densité, chaleur spécifique. . .), mais encore au niveau du procédé lui-même (vitesse de déplacement, nombre et orientation des plis. . .). Nous avons construit un modèle réduit multi-paramétrique en utilisant la technique appelée Proper Generalised Decomposition (PGD). Les résultats ont été confrontés à ceux obtenus par des méthodes plus conventionnelles et aussi à des données expérimentales. / Realising composite parts mainly dedicated to aeronautics sector by robotised processes tends to increase productivity. However, Automated Tape Placement (ATP) is still in ripening stage and requires various developments, particularly in case of thermoplastic composites or dry fibres. In this manuscript, we propose different tools allowing to determine in advance the best heating power to drape composite fibres. Difficulty arises from dependence on many parameters, from material (density, specific heat) or from process itself (velocity, number and orientation of plies). Therefore we construct a multi-parametric reduced order model using the so called Proper Generalised Decomposition (PGD). Results have been faced to those obtained from more conventional methods but also to experimental data.
36

Análise dinâmica não linear bidimensional de risers verticais. / Nonlinear dynamic analysis of bidimensional vertical risers.

Michele Yamao 10 May 2013 (has links)
Na última década foram descobertas jazidas de petróleo e gás em águas profundas ao longo da costa sudeste do Brasil, o que tem levado à reavaliação de conceitos e técnicas até então utilizados para sua exploração em pequenas profundidades. Parâmetros que anteriormente eram supostamente não críticos passaram a ser relevantes no dimensionamento estrutural dos risers. Efetivamente, a descoberta de novas jazidas na Bacia de Santos incentivou o desenvolvimento de pesquisas nesta área, no Brasil e no mundo. Os depósitos de petróleo e gás encontrados abaixo da camada de sal (daí serem referidas por pré-sal) ocorrem em áreas com lâmina dágua de mais de 2.000 metros, requerendo novas tecnologias para viabilizar sua extração. Os risers de produção nada mais são do que tubulações que levam petróleo e gás do fundo do oceano para a superfície. Nas suas diversas configurações geométricas (vertical, em catenária, lazy wave, entre outros), são elementos estruturais extremamente esbeltos, que devem suportar carregamentos dinâmicos oriundos da correnteza marítima em grande profundidade, ondas de superfície, escoamento interno e deslocamentos impostos, atendendo a exigentes critérios de projeto. O riser vertical será o foco deste trabalho, no qual se pretende utilizar modelos matemáticos com poucos graus de liberdade, denominados modelos de ordem reduzida (MOR), mas com adequada capacidade de representação qualitativa e quantitativa da resposta estrutural, fazendo uso de modos não lineares como funções de projeção, dentro do método de Galerkin não linear. Os modos não lineares, intensivamente estudados no Grupo de Pesquisa Dinâmica, Estabilidade e Controle de Sistemas Estruturais da Escola Politécnica da USP, por conterem intrinsecamente informações de harmônicos de ordem superior, são capazes de, em menor número do que os modos lineares utilizados no método da superposição modal clássico, descreverem acuradamente a resposta do sistema não linear. Serão utilizados procedimentos baseados tanto no método das variedades invariantes, quanto no método das múltiplas escalas, em modelos analíticos. Para a redução de graus de liberdade, será utilizado o método de projeção que se baseia na imposição da igualdade entre os trabalhos virtuais dos modelos de alta e baixa hierarquia (MOR), de sorte que o sistema sob carregamento dinâmico possa ser estudado em espaço de fase de baixa dimensão. A presente pesquisa, além dos desafios acadêmicos inerentes ao tema, apresenta evidente relevância econômica e estratégica para o País. / In the last decade, deposits of oil and gas under deep waters were discovered along the Brazilian Southeast coast, which led to reassessment of concepts and techniques previously used for their exploitation under shallow waters. Parameters that were not previously considered to be critical became relevant in the structural design of the risers. Indeed, the discovery of new deposits in the so-called Santos Basin encouraged the development of research in this area in Brazil and worldwide. The oil and gas deposits found in the pre-salt layer occur in waters deeper than 2,000 meters, requiring new technologies to facilitate their extraction. The risers of production are nothing more than pipes that carry oil and gas from the ocean to the surface. In its various geometric configurations (vertical, catenary, lazy waves, etc.), they are extremely slender structural elements, which must withstand dynamic loads from deep currents, surface waves, internal flow and imposed motions, observing the strict design criteria regarding ultimate and service limit states. The vertical riser will be the focus of this work, which uses mathematical models with few degrees of freedom, known as reduced-order models (ROM), but with adequate capacity to represent the structural response both qualitatively and quantitatively, using non-linear modes as projection functions within the non-linear Galerkin method. The non-linear modes were intensively studied in the research group \"Dynamics, Stability and Control of Structural Systems\" at the Escola Politécnica of USP. Because they contain information of higher-order harmonics, they are able to accurately describe the response of the nonlinear system, using a smaller number of modes than the linear modes used in the classical modal superposition method. Procedures based on the method of invariant manifold and the method of multiple scales alike will be applied to analytical continuum models (with infinite number of degrees of freedom). For the reduction of degrees of freedom, a method based on the identification of the virtual works in both the high-hierarchy and the ROM will be used, so that the system under dynamic loading can be studied in a low-dimension phase space. 13 This research, in addition to academic challenges inherent to the subject has obvious economic and strategic importance for the country.
37

POD Approach for Aeroelastic Updating / Approche POD pour le Recalage du Modele Aeroelastique

Vetrano, Fabio 17 December 2014 (has links)
Bien que les méthodes de calcul peuvent donner de bons résultats, ils ne sont généralement pas en accord avec exactement les données d'essais en vol en raison des incertitudes dans les modelé de calcul de structure et aérodynamiques. Une méthode efficace est nécessaire pour la mise à jour des modelé aeroelastiques en utilisant les données d'essais en vol, les données d'essais de vibration au sol ( GVT ) et les données de soufflerie. Tout d'abord tous les développements ont été valides sur une section de l'aile 2D et sur un modèle 3D simple et après l'approche POD a été applique= a une configuration industrielle (modèle de soufflerie aile-fuselage et modèle d' avions complète). / Although computational methods can provide good results, they usually do not agree exactly with the flight test data due to uncertainties in structural and aerodynamic computational models. An effective method is required for updating computational aeroelastic models using the flight test data along with Ground Vibration Test (GVT) data and wind tunnel data. Firstly all developments have been validated on a 2D wing section and on a simple 3D model and after the POD approach has been applied to an industrial configuration (wing-fuselage wind tunnel model and complete aircraft model).
38

Multilevel model reduction for uncertainty quantification in computational structural dynamics / Réduction de modèle multi-niveau pour la quantification des incertitudes en dynamique numérique des structures

Ezvan, Olivier 23 September 2016 (has links)
Ce travail de recherche présente une extension de la construction classique des modèles réduits (ROMs) obtenus par analyse modale, en dynamique numérique des structures linéaires. Cette extension est basée sur une stratégie de projection multi-niveau, pour l'analyse dynamique des structures complexes en présence d'incertitudes. De nos jours, il est admis qu'en dynamique des structures, la prévision sur une large bande de fréquence obtenue à l'aide d'un modèle éléments finis doit être améliorée en tenant compte des incertitudes de modèle induites par les erreurs de modélisation, dont le rôle croît avec la fréquence. Dans un tel contexte, l'approche probabiliste non-paramétrique des incertitudes est utilisée, laquelle requiert l'introduction d'un ROM. Par conséquent, ces deux aspects, évolution fréquentielle des niveaux d'incertitudes et réduction de modèle, nous conduisent à considérer le développement d'un ROM multi-niveau, pour lequel les niveaux d'incertitudes dans chaque partie de la bande de fréquence peuvent être adaptés. Dans cette thèse, on s'intéresse à l'analyse dynamique de structures complexes caractérisées par la présence de plusieurs niveaux structuraux, par exemple avec un squelette rigide qui supporte diverses sous-parties flexibles. Pour de telles structures, il est possible d'avoir, en plus des modes élastiques habituels dont les déplacements associés au squelette sont globaux, l'apparition de nombreux modes élastiques locaux, qui correspondent à des vibrations prédominantes des sous-parties flexibles. Pour ces structures complexes, la densité modale est susceptible d'augmenter fortement dès les basses fréquences (BF), conduisant, via la méthode d'analyse modale, à des ROMs de grande dimension (avec potentiellement des milliers de modes élastiques en BF). De plus, de tels ROMs peuvent manquer de robustesse vis-à-vis des incertitudes, en raison des nombreux déplacements locaux qui sont très sensibles aux incertitudes. Il convient de noter qu'au contraire des déplacements globaux de grande longueur d'onde caractérisant la bande BF, les déplacements locaux associés aux sous-parties flexibles de la structure, qui peuvent alors apparaître dès la bande BF, sont caractérisés par de courtes longueurs d'onde, similairement au comportement dans la bande hautes fréquences (HF). Par conséquent, pour les structures complexes considérées, les trois régimes vibratoires BF, MF et HF se recouvrent, et de nombreux modes élastiques locaux sont entremêlés avec les modes élastiques globaux habituels. Cela implique deux difficultés majeures, concernant la quantification des incertitudes d'une part et le coût numérique d'autre part. L'objectif de cette thèse est alors double. Premièrement, fournir un ROM stochastique multi-niveau qui est capable de rendre compte de la variabilité hétérogène introduite par le recouvrement des trois régimes vibratoires. Deuxièmement, fournir un ROM prédictif de dimension réduite par rapport à celui de l'analyse modale. Une méthode générale est présentée pour la construction d'un ROM multi-niveau, basée sur trois bases réduites (ROBs) dont les déplacements correspondent à l'un ou l'autre des régimes vibratoires BF, MF ou HF (associés à des déplacements de type BF, de type MF ou bien de type HF). Ces ROBs sont obtenues via une méthode de filtrage utilisant des fonctions de forme globales pour l'énergie cinétique (par opposition aux fonctions de forme locales des éléments finis). L'implémentation de l'approche probabiliste non-paramétrique dans le ROM multi-niveau permet d'obtenir un ROM stochastique multi-niveau avec lequel il est possible d'attribuer un niveau d'incertitude spécifique à chaque ROB. L'application présentée est relative à une automobile, pour laquelle le ROM stochastique multi-niveau est identifié par rapport à des mesures expérimentales. Le ROM proposé permet d'obtenir une dimension réduite ainsi qu'une prévision améliorée, en comparaison avec un ROM stochastique classique / This work deals with an extension of the classical construction of reduced-order models (ROMs) that are obtained through modal analysis in computational linear structural dynamics. It is based on a multilevel projection strategy and devoted to complex structures with uncertainties. Nowadays, it is well recognized that the predictions in structural dynamics over a broad frequency band by using a finite element model must be improved in taking into account the model uncertainties induced by the modeling errors, for which the role increases with the frequency. In such a framework, the nonparametric probabilistic approach of uncertainties is used, which requires the introduction of a ROM. Consequently, these two aspects, frequency-evolution of the uncertainties and reduced-order modeling, lead us to consider the development of a multilevel ROM in computational structural dynamics, which has the capability to adapt the level of uncertainties to each part of the frequency band. In this thesis, we are interested in the dynamical analysis of complex structures in a broad frequency band. By complex structure is intended a structure with complex geometry, constituted of heterogeneous materials and more specifically, characterized by the presence of several structural levels, for instance, a structure that is made up of a stiff main part embedding various flexible sub-parts. For such structures, it is possible having, in addition to the usual global-displacements elastic modes associated with the stiff skeleton, the apparition of numerous local elastic modes, which correspond to predominant vibrations of the flexible sub-parts. For such complex structures, the modal density may substantially increase as soon as low frequencies, leading to high-dimension ROMs with the modal analysis method (with potentially thousands of elastic modes in low frequencies). In addition, such ROMs may suffer from a lack of robustness with respect to uncertainty, because of the presence of the numerous local displacements, which are known to be very sensitive to uncertainties. It should be noted that in contrast to the usual long-wavelength global displacements of the low-frequency (LF) band, the local displacements associated with the structural sub-levels, which can then also appear in the LF band, are characterized by short wavelengths, similarly to high-frequency (HF) displacements. As a result, for the complex structures considered, there is an overlap of the three vibration regimes, LF, MF, and HF, and numerous local elastic modes are intertwined with the usual global elastic modes. This implies two major difficulties, pertaining to uncertainty quantification and to computational efficiency. The objective of this thesis is thus double. First, to provide a multilevel stochastic ROM that is able to take into account the heterogeneous variability introduced by the overlap of the three vibration regimes. Second, to provide a predictive ROM whose dimension is decreased with respect to the classical ROM of the modal analysis method. A general method is presented for the construction of a multilevel ROM, based on three orthogonal reduced-order bases (ROBs) whose displacements are either LF-, MF-, or HF-type displacements (associated with the overlapping LF, MF, and HF vibration regimes). The construction of these ROBs relies on a filtering strategy that is based on the introduction of global shape functions for the kinetic energy (in contrast to the local shape functions of the finite elements). Implementing the nonparametric probabilistic approach in the multilevel ROM allows each type of displacements to be affected by a particular level of uncertainties. The method is applied to a car, for which the multilevel stochastic ROM is identified with respect to experiments, solving a statistical inverse problem. The proposed ROM allows for obtaining a decreased dimension as well as an improved prediction with respect to a classical stochastic ROM
39

Experimental and Computational Investigation of a Rotating Bladed Disk under Synchronous and Non-Synchronous Vibration

Kurstak, Eric 13 October 2021 (has links)
No description available.
40

Surrogate models coupled with machine learning to approximate complex physical phenomena involving aerodynamic and aerothermal simulations / Modèles de substitution couplés à de l'apprentissage automatique pour approcher des phénomènes complexes mettant en jeu des simulations aérodynamiques et aérothermiques

Dupuis, Romain 04 February 2019 (has links)
Les simulations numériques représentent un élément central du processus de conception d’un avion complétant les tests physiques et essais en vol. Elles peuvent notamment bénéficier de méthodes innovantes, telle que l’intelligence artificielle qui se diffuse largement dans l’aviation. Simuler une mission de vol complète pour plusieurs disciplines pose d’importants problèmes à cause des coûts de calcul et des conditions d’opérations changeantes. De plus, des phénomènes complexes peuvent se produire. Par exemple, des chocs peuvent apparaître sur l’aile pour l’aérodynamique alors que le mélange entre les écoulements du moteur et de l’air extérieur impacte fortement l’aérothermie autour de la nacelle et du mât. Des modèles de substitution peuvent être utilisés pour remplacer les simulations haute-fidélité par des approximations mathématiques afin de réduire le coût de calcul et de fournir une méthode construite autour des données de simulations. Deux développements sont proposés dans cette thèse : des modèles de substitution utilisant l’apprentissage automatique pour approximer des calculs aérodynamiques et l’intégration de modèles de substitution classiques dans un processus aérothermique industriel. La première approche sépare les solutions en sous-ensembles selon leurs formes grâce à de l’apprentissage automatique. En outre, une méthode de reéchantillonnage complète la base d’entrainement en ajoutant de l’information dans des sous-ensembles spécifiques. Le deuxième développement se concentre sur le dimensionnement du mât moteur en remplaçant les simulations aérothermiques par des modèles de substitution. Ces deux développements sont appliqués sur des configurations avions afin de combler l’écart entre méthode académique et industrielle. On peut noter que des améliorations significatives en termes de coût et de précision ont été atteintes. / Numerical simulations provide a key element in aircraft design process, complementing physical tests and flight tests. They could take advantage of innovative methods, such as artificial intelligence technologies spreading in aviation. Simulating the full flight mission for various disciplines pose important problems due to significant computational cost coupled to varying operating conditions. Moreover, complex physical phenomena can occur. For instance, the aerodynamic field on the wing takes different shapes and can encounter shocks, while aerothermal simulations around nacelle and pylon are sensitive to the interaction between engine flows and external flows. Surrogate models can be used to substitute expensive high-fidelitysimulations by mathematical and statistical approximations in order to reduce overall computation cost and to provide a data-driven approach. In this thesis, we propose two developments: (i) machine learning-based surrogate models capable of approximating aerodynamic experiments and (ii) integrating more classical surrogate models into industrial aerothermal process. The first approach mitigates aerodynamic issues by separating solutions with very different shapes into several subsets using machine learning algorithms. Moreover, a resampling technique takes advantage of the subdomain decomposition by adding extra information in relevant regions. The second development focuses on pylon sizing by building surrogate models substitutingaerothermal simulations. The two approaches are applied to aircraft configurations in order to bridge the gap between academic methods and real-world applications. Significant improvements are highlighted in terms of accuracy and cost gains

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