Ces travaux de thèse sont focalisés sur le développement d’une boucle diphasique LHP pour le contrôle thermique de composants intégrés dans les moteurs aéronautiques. L’étude concerne les compartiments situés à l’intérieur de la nacelle, en lien avec les challenges thermiques des moteurs de future génération. Tout d’abord, une étude de faisabilité a été menée, basée sur une évaluation de l’environnement thermique, une analyse des contraintes d’intégration et une première identification d’un couple fluide de travail-matériau de construction. En ce qui concerne ce dernier aspect, l’eau et le DowthermTM J ont été identifiés comme les meilleurs candidats pour leur utilisation avec les alliages souhaités pour cet environnement. D’un côté, le point triple élevé de l’eau a obligé la vérification de la tenue mécanique du milieu capillaire mouillé à des cycles de gel/dégel. Le milieu poreux fritté en titane a montré une excellente résistance mécanique et il est resté parfaitement intact après plus de 1500 cycles. D’un autre côté, vu le manque d’informations concernant la compatibilité du DowthermTM J avec les matériaux sélectionnés, des tests de compatibilité ont été effectués avec trois thermosiphons en parallèle, et ont montré un taux de génération de gaz non condensables déjà à faible température. Pour cette raison, la compatibilité entre le DowthermTM J et les matériaux a été jugé non satisfaisante et le fluide a été rejeté. L’étape suivante a été la conception d’un prototype de boucle LHP. Des outils numériques robustes ont été développés pour la validation finale : un modèle 0D pour la boucle entière ainsi qu’un modèle couplé 1D - 2D du condenseur. Le prototype de LHP a été construit et testé sous différentes conditions opératoires. Une quantité de gaz non condensable a été observée initialement, due à la passivation des surfaces intérieures à la boucle. Néanmoins, les résultats expérimentaux ont montré que la boucle répond aux cahiers de charge thermique, même en présence de ces gaz,étant capable de fonctionner sous hautes températures et haute pression. La génération de gaz s’est arrêtée après un certain nombre d’heures cumulées de fonctionnement ; pourtant, les inspections internes à l’évaporateur après les tests ont montrés une dégradation significative de l’état de surface, due aux réactions chimiques entre le fluide de travail et les matériaux de la boucle. Les résultats de ces travaux de thèse constituent une étape fondamentale vers le développement d’une boucle LHP pour le contrôle thermique de composants intégrés dans la nacelle. Des informations essentielles à la conception des prototypes de future génération sont fournies, vers la validation et la certification des LHP pour leur utilisation dans cet environnement. / In this work, the development of a Loop Heat Pipe (LHP) for aircraft nacelle thermal management is presented. The study is focused on engine compartments and integrated equipment applications, according to the upcoming thermal management challenges in the next generation of engines. First, a feasibility study was performed, analyzing the thermal environment, the integration constraints and the identification of suitable working fluid construction material pairs. As for the latter aspect, water and DowthermTM J were identified as most suitable candidates with the lightweight aeronautical alloys considered for this environment. On one hand, the high triple point of water obliged to verify the wick mechanical resistance to repeated freezing cycles when soaked into pure water. On the other hand, compatibility tests were performed between DowthermTM J and the selected alloys, due to the lack of related data. In the former, the sintered titanium wick provided an excellent stiffness and it remained perfectly intact after more than 1500 cycles. In the latter, the thermal tests performed on parallel thermosyphon shave clearly shown the generation of non-condensable gases (NCG) inside all the samples starting from low operating temperatures. As a result, the compatibility of DowthermTM J was considered not fully satisfactory and this fluid was discarded. The next step concerned the design of the titanium/water LHP prototype. Robust numerical tools were developed for the final design validation: a simplified 0D nodal model for the entire device and a coupled 1D and 2D condenser model representation. The LHP prototype was manufactured and tested in different operating conditions. A significant amount of NCG was initially generated inside the device, due top assivation of the internal surfaces. Nonetheless, the experimental results demonstrated the LHP capability to satisfy the thermal requirements, even in presence of NCG, with standing high operating temperatures and pressures. Although the gas generation rate became negligible after several hours of tests, internal inspections performed at the end of the test revealed a deep alteration of the internal surface state, due to the chemical reactions with the working fluid. The results of this work represent an important milestone for the development of a LHP for aircraft nacelle applications. Essential information for the design of future generations of prototypes are provided, toward the validation and certification of LHP for nacelle thermal management.

No description available.

The increasing demand of more economical and environmentally friendly aero engines leads to the proposal of a new concept – geared turbofan. In this thesis, the characteristics of this kind of engine and relevant considerations of integration on a flying wing aircraft were studied. The studies can be divided into four levels: GTF-11 engine modelling and performance simulation; aircraft performance calculation; nacelle design and aerodynamic performance evaluation; preliminary engine installation. Firstly, a geared concept engine model was constructed using TURBOMATCH software. Based on parametric analysis and SFC target, the main cycle parameters were selected. Then, the maximum take-off thrust was verified and corrected from 195.56kN to 212kN to meet the requirements of take-off field length and second segment climb. Besides, the engine performance at offdesign points was simulated for aircraft performance calculation. Secondly, an aircraft performance model was developed and the performance of FW-11 was calculated on the basis of GTF-11 simulation results. Then, the effect of GTF-11 characteristics performance on aircraft performance was evaluated. A comparison between GTF-11 and conventional turbofan, RB211- 524B4, indicated that the aircraft can achieve a 13.1% improvement in fuel efficiency by using the new concept engine. Thirdly, a nacelle was designed for GTF-11 based on NACA 1-series and empirical methods while the nacelle dimensions of conventional turbofan RB211-525B4 were obtained by measure approach. Then, the installation thrust losses caused by nacelle drags of the two engines were evaluated using ESDU 81024a. The results showed that the nacelle drags account for about 4.08% and 3.09% of net thrust for GTF-11 and RB211-525B4, respectively. Finally, the considerations of engine installation on a flying wing aircraft were discussed and a preliminary disposition of GTF-11 on FW-11 was presented.

Tidal Energy is one of the growing renewable energy technologies that is aimed at tackling global energy challenges. The Horizontal Axis Tidal Turbine (HATT) is an in-stream Tidal Energy Converter (TEC) which extracts kinetic energy from tidal flows. These tidal turbines face many reliability challenges due to their complexity, harsh operating environment and low accessibility. One of the component contributing significantly to the reliability of a TEC is the bearing supporting the rotating shaft within the nacelle. The reliability assessment of this component is essential during the design process and before their eventual deployments. This work is describes shaft bearing reliability assessment procedures. In recent years, the Offshore Renewable Energy (ORE) Catapult’s National Renewable Energy Centre has developed a dedicated multi axis test facility for full scale testing of tidal turbine nacelles and components (i.e. Nautilus). This work presents a methodology for testing tidal turbine shaft bearings in a representative manner in the full scale nacelle test rig, Nautilus. Two aspects are considered, namely the damage assessment and the damage replication in an accelerated manner. The damage assessment process considers the global loading on the shaft bearing and a Rigid Dynamics (RD) model has been applied to identify the local bearing loads. Local loads are converted to stress enabling the identification of stress-life relationship and bearing damage. The damage replication process is aimed to evaluate the 20 year damage and the Acceleration by Phase-shift (AbP) method has been developed to accelerate the cumulative damage. The AbP method enables the assessment of performance characteristics of shaft bearings in a laboratory environment, reducing failure rates, validate performance in a cost effective manner by reduced testing times. Within this work, novel processes for shaft bearing reliability assessments and demonstration are suggested and it concludes with the presentation of a recommended test plan for carrying out accelerated tests on a full scale bearing.

With the growing demand of renewable wind energy, logistics and operations associated with a wind turbine makes for compelling study and analysis. The study entails understanding of transporting a wind turbine nacelle from Denmark till Australia. The methods of transporting the wind turbine nacelle and the modes of transportation that are currently in use have been studied. Factors that are detrimental to efficient shipping have been reviewed with existing literature and analysed for a wind turbine nacelle. The two key factors that influence transportation namely humidity and G-force have been identified. Simple and cost effective solutions such as use of insulation material, use of desiccants to overcome the effects of humidity, use of shock absorber pallets to reduce shock and vibration have been proposed. For the damages caused to a wind turbine nacelle due to random causes, some suggestions to prevent such damages have also been provided.

Cette thèse étudie des méthodes de conception aérodynamique pour les avions de ligne de demain. A l'heure actuelle, les avions de ligne sont en général conçus de manière à ce que les moteurs, conçus séparément du reste de l'aéronef, n'interagissent que très peu avec la cellule de l'avion (la voilure, le fuselage,...). Pour diminuer la consommation de carburant, de nouveaux concepts comme l'ingestion de couche limite émergent, dans lesquels l'avion est conçu pour tirer profit des interactions aérodynamiques qui peuvent s'établir entre le moteur et la cellule de l'avion sur certaines configurations. Il devient alors nécessaire de simuler ces interactions pour s'assurer que le bénéfice pour l'avion en termes de consommation de carburant est réel. La méthode développée dans cette thèse a pour objectif de rendre possible la simulation de ces interactions, à un coût de calcul qui reste acceptable. La soufflante, qui est l'élément du moteur le plus à même d'interagir avec l'avion, est modélisée à l'aide d'un champ de force qui reproduit son aspiration de l'écoulement d'air. Cette approche permet de reproduire les interactions aérodynamiques entre l'avion et ses moteurs à un coût 50 fois inférieur à celui d'une simulation complète du moteur et de l'avion, ce qui permettra en pratique d'optimiser les lignes aérodynamiques des futurs avions. / This work explores new méthodologies for the aerodynamic conception of future commercial aircraft. In general, commercial aircraft are designed to limit aerodynamic interactions between the engines and the airframe. New aircraft concepts such as boundary layer ingestion are now studied, in which the aircraft is designed to take advantage of these interactions. It is then necessary to be able to simulate these interactions to ensure that real benefits in terms of aircraft fuel burn are possible. The methodology that is developed in the présent thesis aims at enabling the simulation of these aerodynamic interactions at affordable computational cost. The fan, which is the part of the engine the most likely to internet with the airframe, is modeled using a force field that reproduces the suction of the air inside the engine. This approach allows to reproduce fan- airframe interactions at a fraction of the cost of a complété simulation of the aircraft and the engines, and enable the practical optimization of the aerodynamic performance of future aircraft.

Esse trabalho descreve uma investigação prática e teórica de características aerodinâmicas de um modelo referente a um avião bimotor leve \"Piper PA-34 SENECA III\" construído em escala 1:6,5. Basicamente, duas configurações fazem parte da avaliação: \"asa limpa\" e Nacele \"Pusher\". O principal objetivo é o de avaliar o comportamento aerodinâmico da configuração \"Pusher\" em três diferentes posições através da obtenção de dados práticos e teóricos de distribuição de pressão estática no aerofólio e no próprio nacele na condição não motorizada. A metodologia emprega testes em túnel de vento de baixa velocidade para a aquisição dos dados experimentais através da variação do ângulo de ataque para as configurações citadas. A obtenção dos dados numéricos, como comparativos aos experimentais, é através da utilização do método dos painéis aplicado à aerodinâmica. Os resultados experimentais e teóricos mostram que a presença do nacele nas posições \"Pusher\" avaliadas gera interferência diminuindo à sustentação do aerofólio. / This work describes a practical and theoretical investigation of aerodynamic characteristics of a 1:6,5 scale model of a light twin-engined Piper Seneca III aircraft. Basically, two configurations are considered in this evaluation: clean wing and pusher nacelle. The principal objective is to evaluate the aerodynamic characteristics of the pusher configuration in three different positions, in order to obtain practical and theoretical data with reference to static pressure distribution on the surface of the aerofoil and of the nacelle in a power-off condition. The methodology employed used low speed wind tunnel test for the acquisition of experimental data for a selection of angles of attach, as cited. The generation of numerical data, to be compared the experimental equivalent, is though the use of a low order panel method. The experimental and theoretical results show that the presence of pusher nacelle in the positions mentioned generated interference, reducing the local lift of the aerofoil.

La conception des nacelles doit répondre à des contraintes géométriques d’encombrement mais aussi à des spécifications motoristes qui précisent les niveaux de performance exigés. Au sol, l’une des principales contraintes imposées par le motoriste concerne le niveau de distorsion de pression totale dans le plan fan quand la nacelle est soumise à un vent de travers. Dans le cas le plus limitant, c’est-à-dire lorsque la direction du vent est perpendiculaire à l’axe de la nacelle, il se produit un décollement au niveau de l’entrée d’air côté vent. L’hétérogénéité de l’écoulement crée des efforts instationnaires sur les aubes du fan. Ces efforts peuvent amener à un régime de pompage endommageant ainsi le moteur. De plus, la tendance actuelle est de réaliser des nacelles courtes, réduisant la distance qu’à l’écoulement pour s’homogénéiser avant d’impacter le fan, conduisant à un couplage entre le décollement et le fan. Le but de cette étude est de simuler numériquement l’écoulement intervenant dans une nacelle courte soumise à un vent de travers et d’étudier l’impact de la présence du fan. Tout d’abord, la définition de la distorsion est basée sur les grandeurs totales. Ainsi, la compréhension du comportement des grandeurs totales au voisinage d’une paroi et l’influence des paramètres numériques sur leur évolution est nécessaire. Une approche analytique et numérique sur plaque plane a permis d’évaluer le comportement des grandeurs totales à la frontière externe de la couche limite et l’influence des paramètres numériques RANS sur leur évolution. Cette étude a permis de choisir les paramètres numériques utilisés pour la simulation de la nacelle. Pour faire ressortir l’influence du fan sur la distorsion, deux types de simulations ont été menés : une simulation de nacelle isolée et une simulation de l’ensemble complet nacelle/fan respectivement comparées à un essai en soufflerie sur une maquette de nacelle isolée et à un essai de moteur complet à échelle 1 :1 réalisé en « soufflerie » à veine ouverte. La description correcte de la distorsion nécessite de prendre en compte les phénomènes de transition. Une méthode innovante de prise en compte de la transition par équations de transport est utilisée. Comme le coût de calcul de l’ensemble complet est prohibitif, la question du découplage du calcul en injectant une distorsion, issue d’une simulation de nacelle isolée, dans un calcul de fan isolé est discutée. La distorsion par vent de travers intervient lorsque l’avion est au sol. Par conséquent, l’impact de la présence du sol est étudié dans le cas de la nacelle isolée. Enfin, le critère de distorsion utilisé présente plusieurs défauts importants et peut être remis en cause. Une nouvelle méthode de mesure et de calcul estétudiée. / Inlet design must fulfill geometrical constraints and engine requirements. One of these requirementsis the homogeneity of the flow impacting the fan which is quantified by the distortionlevels of stagnation pressure. When the airplane is on the ground and ready to take-off, crosswindconditions are critical for the distorsion level. The most critical case is when the wind directionis normal to the engine axis. Subsonic and supersonic separations occur near the inlet lip. Theso-created heterogeneity produces an unsteady stress on the fan blades which can lead to surge.Furthermore, short inlets are designed nowadays reducing the distance available for the flow tohomogenize before the fan leading to a coupling between the fan and the separated flow region.The aim of this study is to numerically predict the flow in a short inlet under crosswind conditionsand to investigate the fan influence on the distortion. First of all, the distortion definition isbased on stagnation quantities. Therefore, the stagnation quantities behavior and the numericalparameters influence must be investigated. The behavior of the stagnation quantities near theboundary layer edge is studied with analytical and numerical approaches. The numerical parameterschosen for the inlet simulation come from the so-obtained results obtained. In order tohighlight the fan influence on the distortion, two kinds of simulations were proceeded and comparedto experimental results : an isolated inlet simulation and a inlet/fan simulation. To correctlypredict the distortion, transition has to be be taken into account. Therefore an innovative solutionusing transport equations is used. As the computation cost for the inlet/fan computation isprohibitive, the decoupling which consists in injecting on a isolated fan the distortion obtainedduring a isolated inlet computation, is discussed. In fact, crosswind conditions occur when theairplane is on the ground, thus, the ground influence over the inlet distortion is studied for anisolated inlet. Finally, the distortion criterion used in this study has evidenced some strong defectsand can be questioned. Another approach of measurement with another criterion definitionis investigated.

Esse trabalho descreve uma investigação prática e teórica de características aerodinâmicas de um modelo referente a um avião bimotor leve \"Piper PA-34 SENECA III\" construído em escala 1:6,5. Basicamente, duas configurações fazem parte da avaliação: \"asa limpa\" e Nacele \"Pusher\". O principal objetivo é o de avaliar o comportamento aerodinâmico da configuração \"Pusher\" em três diferentes posições através da obtenção de dados práticos e teóricos de distribuição de pressão estática no aerofólio e no próprio nacele na condição não motorizada. A metodologia emprega testes em túnel de vento de baixa velocidade para a aquisição dos dados experimentais através da variação do ângulo de ataque para as configurações citadas. A obtenção dos dados numéricos, como comparativos aos experimentais, é através da utilização do método dos painéis aplicado à aerodinâmica. Os resultados experimentais e teóricos mostram que a presença do nacele nas posições \"Pusher\" avaliadas gera interferência diminuindo à sustentação do aerofólio. / This work describes a practical and theoretical investigation of aerodynamic characteristics of a 1:6,5 scale model of a light twin-engined Piper Seneca III aircraft. Basically, two configurations are considered in this evaluation: clean wing and pusher nacelle. The principal objective is to evaluate the aerodynamic characteristics of the pusher configuration in three different positions, in order to obtain practical and theoretical data with reference to static pressure distribution on the surface of the aerofoil and of the nacelle in a power-off condition. The methodology employed used low speed wind tunnel test for the acquisition of experimental data for a selection of angles of attach, as cited. The generation of numerical data, to be compared the experimental equivalent, is though the use of a low order panel method. The experimental and theoretical results show that the presence of pusher nacelle in the positions mentioned generated interference, reducing the local lift of the aerofoil.

This diploma thesis deals with the flow analysis around the landing gear nacelle of L 410 and with its following aerodynamical optimalization. In the first part the calibration is performed on the known geometry which was tested in wind tunnel. The following parts contain own design of the optimal geometry, design of the computional mesh with its numerical solution and results evaluation.