RESUME : Les machines axiales à rotors contrarotatifs subsoniques sont une bonne solution pour les industries où de fortes élévations de pressions et d'efficacités sont nécessaires sans augmenter le diamètre ou la vitesse de rotation des rotors. Néanmoins, le comportement des CRS et les paramètres impactant ses performances ne sont pas encore totalement compris. Cette thèse mène une investigation expérimentale sur la performance et les paramètres influents sur un étage contrarotatif. La technique de design et les méthodes de mesure sont repris sur une thèse précédente réalisée au laboratoire Dynfluid (Arts et métiers ParisTech). Trois étages contrarotatifs ont été fabriqués (JW1, JW2 et JW3) et testés sur le banc d'essai normalisé AERO2FANS. Ces machines ont été conçues pour avoir le même point de fonctionnement mais avec une répartition de charge différente. Les résultats expérimentaux se concentrent dans un premier temps sur JW1. Les grandeurs physiques regardées sont l'efficacité globale et l'élévation de pression statique pour juger de la performance globale de la machine. La fluctuation de pression pariétale et le champ de vitesse sont aussi mesurés. L'impact du changement de rapport de vitesse ou la distance entre les deux rotors sur la machine JW1 a été étudiée grâce aux grandeurs physiques décrits précédemment. Enfin dans une dernière partie, les trois machines sont comparées toujours grâce aux grandeurs physiques définies précédemment. / ABSTRACT : The counter rotating subsonic axial flow fans could be a good solution for applications where the highly improved static pressure and efficiency are required without the increase of rotational speed and fan diameter. However, the mechanisms of high performance CRS and parameters influences are not well understood nowadays. This thesis is an experimental investigation of the performance and parameter studies of two counter rotatingaxial flow ducted fans. The design and measurement methods are based on the previous research work in Laboratory Dynfluid (Arts et Métiers ParisTech). Three Counter Rotating Stages (CRS) (named JW1, JW2 and JW3) are developed and tested on a normalized test bench (AERO2FANS). These systems have same design point and differ by the distribution of loading as well as the ratio of angular velocity between the Front Rotor (FR) and Rear Rotor (RR). The first part of results focus on the JW1. The overall performance is obtained by the experimental results of the static pressure rise and static efficiency, as well as the wall pressure fluctuations recorded by a microphone on the casing wall. The parameter study is conducted to investigate the effects of the axial distance and the ratio of angular velocity between the FR and RR on the global performance and flow fields measured by Laser Doppler Velocimetry (LDV).The last part of the work is devoted to analyze the differences of the three CRS with different distribution of work, in terms of the global performance and flow features.

Ce travail de thèse, mené dans le cadre d’une convention CIFRE entre Snecma, le CERFACS et le LMFA, s’inscrit dans un contexte d’amélioration des performances et d’extension de la plage de fonctionnement des compresseurs de type axial équipant les turboréacteurs. L’une des principales difficultés rencontrée dans cette démarche concerne la maîtrise des écoulements dans la zone de jeu en tête des aubes rotors et qui peuvent entraîner une perte de stabilité du système (pompage et décollement tournant).Une solution technologique prometteuse pour améliorer la stabilité est le traitement de carter qui consiste en un dispositif passif complexe de fentes implantées au carter au droit des rotors. En vue d’en améliorer sa conception, les travaux de thèse visent plus particulièrement à approfondir la compréhension des mécanismes d’action grâce à une approche numérique CFD avec le code elsA développé par l’ONERA et le CERFACS, en modélisation stationnaire et instationnaire. Ces travaux s’articulent autour de trois axes principaux. Le premier a eu pour objectif de développer un outil numérique d’aide à la compréhension des mécanismes d’action des traitements de carter et de diagnostic de leur efficacité. Le principe de l’outil, qui est une extension du modèle initialement proposé par Shabbir et Adamczyk, repose sur une évaluation des contributions des termes des équations de Navier-Stokes stationnaires et instationnaires sur un volume de contrôle pris dans l’écoulement. Dans le cas pratique, cela revient à quantifier les efforts appliqués sur le fluide. Le second axe traite de l’analyse des mécanismes d’action des traitements de carter axisymétriques dans deux compresseurs axiaux : l’un subsonique à carter cylindrique (CREATE) et l’autre transsonique à carter conique (NASA Rotor 37). Les enseignements de cette étude indiquent que ce type de géométrie est marqué par son effet d’aspiration de fluide dans la veine. Ce mécanisme est d’autant plus amplifié par un phénomène d’interaction complexe des fentes avec l’écoulement de jeu et la proximité de l’intrados de l’aube adjacente. Cette partie s’est également attardé à la réponse des rainures à un phénomène instationnaire de type sillage de roue amont. Les résultats ont montré que les fentes amortissent les fluctuations de gradient de pression adverse. Le troisième axe porte sur l’analyse des mécanismes des traitements de carter non-axisymétriques à travers l’étude numérique d’un cas test transsonique à carter cylindrique (CBUUA). Le mécanisme d’action améliorant la stabilité de la machine tient en la capacité des fentes à limiter la migration dans la direction circonférentielle du vortex de jeu. Les résultats montrent que ce type de géométrie est caractérisé par son effet de réinjection d’air qui vient ré-énergétiser l’écoulement proche carter. / This thesis work, conducted as part of a CIFRE agreement between Snecma, CERFACS and LMFA, deals with the context of improving performance and extending the operating range of axial compressors fitted turbojets. One of the main difficulties in this approach is the flow control in the rotor tip region, which can cause the loss of the system stability (surge and rotating stall). A promising technology known to bring substantial stability is the casing treatment. This passive control device consists of slots of complex geometry within the rotor casing. In order to improve its design, the thesis aimed specifically at improving the understanding of their mechanisms through a numerical approach using the CFD code elsA developed by ONERA and CERFACS, with steady and unsteady approaches. This work focused on three main axes. The first concerns the development of a numerical tool to support the understanding of casing treatment mechanisms and the diagnosis of their efficiency. The principle of the tool, which is an extension of the model originally proposed by Shabbir and Adamczyk, is based on an assessment of the contributions of the terms of the steady and unsteady Navier-Stokes equations on a control volume taken in the flow. In practice, this permits to quantify the forces applied to the fluid. The second axis deals with the analysis of the flow mechanisms induced by axisymetric casing treatments in two axial compressors : one subsonic with a cylindrical casing (CREATE) and the other transonic with a conical casing (NASA Rotor 37). The findings of this study indicate that this type of geometry is characterized by its bleeding effect. This mechanism is further amplified by a complex phenomenon of interaction between grooves, tip leakage vortex and the proximity to the pressure side of the adjacent blade. This part has also dwelt on the groove’s response to unsteady upstream stator wakes. The results showed that the slots are able to damp fluctuations of adverse pressure gradient. The third area concerns the analysis of the flow mechanisms induced by non-axisymmetric casing treatment through the numerical study of a transonic compressor with cylindrical casing (CBUUA). The mechanism leading to an enhancement of the stability results in slots ability to limit the migration in the circumferential direction of the tip leakage vortex. The results show that this type of geometry is characterized by its effect of re-injection of fluid that comes re-energize the near casing flow.

The advancement in manufacturing technologies to produce high-performing engineered wood products (EWP) has allowed wood to be utilized beyond the traditional low-rise light-frame structures and to become a viable material option for much larger structures. Although glued-laminated timber (glulam) is included as a material option in the current blast code (CSA, 2012), its response to blast loading is not yet well documented. An experimental program investigating the behaviour of seventy glulam beams and columns was developed with focus on establishing the dynamic characteristics of glulam beams and columns with and without the effect of FRP reinforcement. A shock tube capable of simulating high strain rates similar to those experienced during blast was used. Thirty-eight beams with three different cross-sections were tested statically and dynamically to establish the high strain rate effects (dynamic increase factor). Six columns were also tested dynamically with axial load levels ranging from 15 to 75 % of the columns’ compression design capacity. Different retrofit configurations varying from simple tension reinforcement to U-shaped tension reinforcement with confinement using both unidirectional and bi-directional FRP were investigated on a total of twenty-six beams. A procedure capturing the strain-rate effects, variable axial load and FRP, was developed and found to be capable of predicting the flexural behaviour of the beams up to maximum resistance with reasonable accuracy when compared to experimentally obtained static and dynamic resistance curves. Implications on the design of both retrofitted and unretrofitted specimens are also discussed.

Cette thèse porte sur l'étude de machines polyentrefers et leurs limitations, dans le contexte d'avion plus électrique et du projet de déplacement des avions au sol. Ces moteurs, basés sur l'utilisation de plusieurs éléments mobiles et fixes mis en parallèle, permettent d'obtenir de hautes performances. Une étude sur les tolérances des dimensions des éléments actifs montre que les performances peuvent être dégradées si des précautions lors de la réalisation ne sont pas prises et si les entrefers utilisés ne sont pas faibles. Ce manuscrit présente un système totalement innovant permettant d'utiliser un entrefer réduit à son minimum sans que les performances ne soient dégradées par de la friction. Ce système est appelé système de compensation des efforts de plaquage. Afin de développer un moteur tournant à entraînement direct dans le cadre du taxiage des avions, deux topologies différentes de machines discoïdes sont étudiées et dimensionnées. Les résultats favorisent l'utilisation d'une des deux structures, à entrefer réduit, pour réaliser un maximum de couple dans le volume donné. Afin de prouver la faisabilité du système innovant sur un moteur discoïde, la réalisation d'un prototype laboratoire complet est proposée. Des simulations thermiques et du comportement du système innovant permettront de valider ces études. / This thesis focuses on the study of multi-air gap machines and their limitations, in the framework of more electric aircraft and the project of moving aircrafts on the ground without the main engines. These motors, based on the use of mobile and fixed parts disposed in parallel, induce high performance. A study concerning the tolerance for the dimensions of active parts shows that performance can decrease if precautions are not taken during manufacturing and if the air gaps are not small. This manuscript presents a totally innovative system that permits the use of an air gap reduced to its minimum without reducing performance by friction. This system is called system of attraction control. In order to develop a direct-drive motor for aircraft taxiing, two different topologies of disc-type machines are studied and sized. The obtained results encourage the use of one of the two structures with reduced air gap to realize maximum torque in the fixed volume. To prove the feasibility of the innovative system on a disc-type motor, the conception of an entire laboratory prototype is proposed. Thermal modelling and simulations on the innovative system behaviour will validate the presented work.

[pt] Uma linha de pesquisa de grande interesse no estudo de colunas de perfuração de poços de petróleo aponta para a necessidade de se aumentar a taxa de penetração (ROP) na perfuração em rochas duras. Procurando suprir tal necessidade, este trabalho tem como objetivo estudar mecanismos e propor um novo dispositivo, utilizando as próprias vibrações geradas na coluna durante a perfuração. As várias formas de vibrar da coluna são, geralmente, indesejadas durante a perfuração. Porém, é possível utilizar algumas destas formas de vibrar para melhorar a eficiência do processo de perfuração. Inicialmente, avalia-se a influência das vibrações torcional e axial na ROP. Posteriormente, estuda-se a perfuração na ressonância e alguns aspectos e cuidados no uso desta nova técnica de perfuração, que vem sendo desenvolvida por empresas do setor. Por fim, é desenvolvido um novo dispositivo de perfuração, chamado de perfuração com martelo em ressonância ou perfuração percussiva- rotativa auto-excitada. Este dispositivo tem como premissa usar a vibração axial gerada no processo de corte, para criar uma carga harmônica na broca e excitar uma massa de aço (martelo). Desenvolve-se um modelo com vibro-impacto e atrito seco, representando o martelo e a resistência da rocha, respectivamente. Faz-se aqui, um estudo numérico e uma validação experimental do movimento percussivo de um modelo que representa a broca com este novo dispositivo. Os resultados mostram que a melhor forma do dispositivo operar é impactando a cabeça da broca, em condição de período-1, com um impacto por ciclo de forçamento. Adicionalmente, os parâmetros do experimento são identificados e os resultados numérico-experimental são comparados, mostrando que são similares. / [en] An area of interest in the study of drillstrings is due to the device of increasing the rate of penetration (ROP) in hard rocks. Trying to supply such necessity, this work aims to study mechanisms and to propose a new device, using vibrations generated in the drillstring itself. The various forms of drillstring vibrations are generally regarded as detrimental in the question. However, it is possible to use some of these vibrations forms in such a way as to enhance drilling performance. Initially, the influence of the torsional and axial vibrations in ROP is analyzed. Next, the resonance drilling, that is being developed by companies in this area, and some aspects and cares in the use of this new drilling technique are studied. At the end, a new drilling device, called resonance hammer drilling or self excited percussive rotary drilling, is developed. This device has as premise to use the axial vibration due to the cutting process, to generate a harmonic load at the bit and to excite a steel mass (hammer). A model with vibro-impact and dry friction is developed, representing the hammer and the resistance of the medium, respectively. It is presented a numeric study and an experimental validation of the percussive motion of the model, that represent the bit. The results show that the best way of the hammer to operate is impacting the bit head, in period-1 condition, ie, with one impact per cycle. Moreover, the experimental parameters are identified and since the numerical-experimental results are similar, the model used is validated.

Cette thèse s’intéresse à l’analyse de structures de machines électriques non conventionnelles destinées à la production d’électricité par des groupes électrogènes. Les topologies recherchées doivent utiliser moins de matières actives et/ou simplifier la procédure de fabrication par rapport aux machines actuelles.Une des structures est dédiée au système d’excitation de la machine. Elle possède un stator à griffes avec un bobinage toroïdal. Son dimensionnement est réalisé à l’aide d’un modèle de calcul par éléments finis en 3D, qui a été validé expérimentalement. Cette structure permet d’obtenir une réduction significative de la quantité de cuivre dans le bobinage.Les deux autres structures traitées concernent l’alternateur principal. Une machine synchro-réluctante à barrières deflux et à rotor bobiné a été proposée. L’objectif est d’augmenter la densité de couple grâce au couple de saillance. Elle est dimensionnée et comparée avec la structure conventionnelle. Ce cas met en évidence les limitations des structures proches de la structure actuelle.La dernière structure est une nouvelle topologie de machine électrique. Elle combine les caractéristiques des machines à flux axial et des machines à griffes, permettant de simplifier le système d’excitation. Une approche de modélisation originale a été développée pour l’analyse de cette topologie 3D en vue de son dimensionnement par optimisation. Le système d’excitation a un rôle important dans les performances de cette machine.Cette thèse constate aussi que l’évolution future des matériaux magnétiques pourrait tirer meilleur profit des structures non-conventionnelles avec des trajets de flux tridimensionnels. / The PhD project aims to analyse nonconventional structures of electric machines for electric power generation with diesel gensets. The researched topologies should use less active materials and/or simplify the manufacturing process compared to today’s machines.One of the structures is intended for the excitation system of the electric machine. It is composed of a claw-pole stator and a toroidal winding. It is designed using a 3D Finite Element model, previously validated by a prototype. This structure allows a significant reduction of the quantity of copper of the field winding.The other two structures under study are proposed for the main generator. A synchronous-reluctance machine with flux-barriers and a field winding in the rotor is analysed. The objective is to increase the torque density by increasing the reluctance torque. The designed machine is compared to the conventional structure. This case shows the limitations of structures similar to the current structure.The last structure is a new topology of electric machine. It combines the characteristics of claw-pole machines andaxial-flux machines. An original modelling approach is developed to analyse this 3D structure for its design based on an optimization algorithm. The study shows that the excitation system has a key role in its performances.This work also notes that the future evolution of magnetic materials should benefit the use of non-conventional structures with 3D flux paths.

La myopie est maintenant considérée comme un problème de santé publique. La forte myopie est associée à des pathologies oculaires comme le glaucome, les cataractes précoces et les problèmes de rétine. La longueur axiale de l’oeil, en plus de sa réfraction, sont des mesures importantes pour assurer le suivi de la progression myopique. Bien que ces variables aient été étudiées en position primaire, peu d’auteurs se sont penchés sur leur variation en périphérie. Ce mémoire a pour principal objectif d’étudier, chez des myopes, la variation de la longueur axiale du centre vers la périphérie de la rétine dans les méridiens horizontaux et verticaux. De plus, elle vise à investiguer si la relation qui existe entre la longueur axiale et la réfraction de l’oeil varie selon l’angle auquel ces variables sont mesurées. 53 participants (83% F; 25,6 ± 2,7 ans) ont été recrutés pour cette étude. Trente minutes après l’instillation de gouttes permettant la dilatation pupillaire, des mesures de longueurs axiales (Lenstar) et de réfractions (Grand Seiko WAM-5500) en position primaire et en périphérie ont été prises en rétine horizontale (10°, 20°, 30°) et verticale (5°, 10°) par rapport à la fovéa. Les résultats obtenus montrent une symétrie horizontale de la longueur axiale jusqu’à une excentricité de 20° et suggèrent une symétrie sur 360° jusqu’à 10°. L’analyse statistique a également permis de confirmer que la relation entre la longueur axiale et la réfraction demeurait la même jusqu’à 20° en nasal, alors qu’elle changeait significativement à 20° en rétine temporale. En comparant la rétine nasale à la rétine temporale, les relations obtenues à 10° étaient similaires, alors que les relations obtenues à 20° étaient différentes. En conclusion, la longueur axiale de l’oeil ainsi que sa relation avec la réfraction demeurent symétriques jusqu’à des angles qui varient entre 10 et 20 degrés. Ceci pourrait influencer la conception des produits optiques développés pour le contrôle de la progression de la myopie. / Today, myopia is considered a public health issue. High myopia is associated with eye pathologies such as glaucoma, early cataracts and retinal abnormalities. In fact, the axial length of the eye, in addition to its refraction, are important measures for monitoring myopic progression. Although these variables have been studied in the central retina, few authors have examined their variation in the peripheral retina. The main objective of this study is to evaluate the variation in the axial length from the center to the periphery of the retina in the horizontal and vertical meridians of myopes. In addition, it aims to investigate whether the relationship between axial length and refraction varies depending on the angle at which these variables are measured. 53 participants (83% F; 25.6 ± 2.7 years) were recruited for this study. Thirty minutes after instillation of drops causing pupillary dilation, measurements of central and peripheral axial lengths (Lenstar) and refractions (Grand Seiko WAM-5500) were taken on the horizontal (10°, 20°, 30°) and vertical (5°, 10°) meridians of the retina relative to the fovea. The results demonstrate horizontal symmetry of the axial length up to an eccentricity of 20° and suggest a symmetry over 360° up to an angle of 10°. Statistical analysis also confirmed that the relationship between axial length and refraction remained the same up to 20° nasally, while it changed significantly at 20° temporally. By comparing the nasal retina to the temporal retina, the relationships obtained at 10° were similar, while the relationships obtained at 20° were different. In conclusion, the axial length of the eye as well as its relation to refraction remain symmetrical up to angles varying between 10 and 20 degrees. This could influence the design of optical products developed for the control of the progression of myopia.

[pt] A união de materiais por soldagem é um dos processos mais utilizados na fabricação de estruturas. A soldagem traz maior confiabilidade, segurança ao projeto e resistência mecânica das uniões. Atualmente, diversas indústrias, tais como aeronáutica e automotiva, têm procurando utilizar materiais de baixa densidade e alta resistência mecânica, como as ligas de magnésio e de alumínio. Porém, estas ligas dificultam o processo de união através da soldagem convencional, que tem no seu principal fundamento a fusão do material, por possuírem baixa soldabilidade. Nas ligas de Mg e de Al há a formação uma camada de óxido que precisa ser removida durante o processo de soldagem, além de apresentarem grande susceptibilidade a geração de defeitos, tais como trincas e poros durante o processo de resfriamento da solda. A soldagem por fricção ou por mistura mecânica (FSW) foi desenvolvida como uma alternativa às técnicas de soldagem e uso mais comum existente na indústria, pois esta técnica elimina a fusão do material reduzindo, assim, os defeitos que surgiriam com a soldagem convencional. Por ser uma solda de estado sólido, tem a possibilidade de unir materiais dissimilares, polímeros, compósitos, ligas ferrosas e não ferrosas. O presente trabalho buscou avaliar parâmetros de soldagem variando a velocidade de soldagem (ν) e velocidade de rotação da ferramenta (ômega) utilizando uma ferramenta com rosca. Foram analisados o torque e as forças presentes no processo. Os resultados foram comparados com os resultados obtidos com uma ferramenta de soldagem sem rosca. A qualidade da solda foi correlacionada com os parâmetros de soldagem utilizados por meio de ensaios de dureza e tomografia. Foi concluído que a ferramenta com rosca gera defeito de túnel e demanda maior energia do processo em relação ao torque e à força axial. O comportamento das forças envolvidas no processo foi o mesmo para ambas as geometrias de ferramenta. A microdureza ao longo do eixo neutro mostrou a mudança entre a zona de mistura, zona termicamente afetada e o metal de base. / [en] The joining of materials by welding is the process most used in the fabrication of structures. Welding brings greater reliability, safety to the design and mechanical strength of the joints. Today, many industries, such as aeronautics and automotive, are looking to use low density and high mechanical strength materials such as magnesium and aluminum alloys. However, these alloys hinder the bonding process through conventional welding, which has in its main foundation the melting of the material, because they have low weldability. In Mg and Al alloys there is a layer of oxide that needs to be removed during the welding process, besides being very susceptible to the generation of defects, such as cracks and pores during the process of cooling the weld. Friction stir welding (FSW) was developed as an alternative to most commonly used in industry welding techniques, as this technique eliminates melting of the material thus reducing defects that would arise with conventional welding. To being a solid state weld, it has the possibility of joining dissimilar materials, polymers, composites, ferrous and non-ferrous alloys. The present work seeked to evaluate welding parameters by varying the welding speed (ν) and tool rotation (omega) using a threaded tool. The torque and forces were analyzed and the results will be compared with the results obtained with a threadless welding tool. The quality of the weld will be correlated with the welding parameters used by means of hardness test and tomography. It was concluded that the threaded tool generates tunnel defect and demands higher process energy. The behavior of the forces involved in the process was the same for both tool geometries. The microhardness along the neutral axis showed the clear the change between the mixing zone, thermally affected zone and the base metal.

This paper presents a non-linear finite element model (FEM) used to predict the behaviour of slender concrete filled steel tubular (CFST) columns with elliptical hollow sections subjected to axial compression. The accuracy of the FEM was validated by comparing the numerical prediction against experimental observation of eighteen elliptical CFST columns which carefully chosen to represent typical sectional sizes and member slenderness. The adaptability to apply the current design rules provided in Eurocode 4 for circular and rectangular CFST columns to elliptical CFST columns were discussed. A parametric study is carried out with various section sizes, lengths and concrete strength in order to cover a wider range of member cross-sections and slenderness which is currently used in practices to examine the important structural behaviour and design parameters, such as column imperfection, non-dimension slenderness and buckling reduction factor, etc. It is concluded that the design rules given in Eurocode 4 for circular and rectangular CFST columns may be adopted to calculate the axial buckling load of elliptical CFST columns although using the imperfection of length/300 specified in the Eurocode 4 might be over-conservative for elliptical CFST columns with lower non-dimensional slenderness.

No / PURPOSE: To estimate refractive indices used by the Lenstar biometer to translate measured optical path lengths into geometrical path lengths within the eye. METHODS: Axial lengths of model eyes were determined using the IOLMaster and Lenstar biometers; comparing those lengths gave an overall eye refractive index estimate for the Lenstar. Using the Lenstar Graphical User Interface, we noticed that boundaries between media could be manipulated and opposite changes in optical path lengths on either side of the boundary could be introduced. Those ratios were combined with the overall eye refractive index to estimate separate refractive indices. Furthermore, Haag-Streit provided us with a template to obtain 'air thicknesses' to compare with geometrical distances. RESULTS: The axial length estimates obtained using the IOLMaster and the Lenstar agreed to within 0.01 mm. Estimates of group refractive indices used in the Lenstar were 1.340, 1.341, 1.415, and 1.354 for cornea, aqueous, lens, and overall eye, respectively. Those refractive indices did not match those of schematic eyes, but were close in the cases of aqueous and lens. Linear equations relating air thicknesses to geometrical thicknesses were consistent with our findings. CONCLUSION: The Lenstar uses different refractive indices for different ocular media. Some of the refractive indices, such as that for the cornea, are not physiological; therefore, it is likely that the calibrations in the instrument correspond to instrument-specific corrections and are not the real optical path lengths.