Rural electrification has long been the most important topic on the development agenda of many countries. The needs for power supplies to rural areas increased significantly in the past decades. Extending electricity grids to rural areas is of a very high initial cost and is not viable economically. Micro hydroelectric power plants provide a good economical solution, which is also environmentally very friendly. The current study concentrates on selecting and optimizing a suitable cross-flow micro-turbine to be used in micro hydroelectric power plants. Cross-flow turbines are in general of simple structure, low cost, easy to fabricate and of modest efficiency. The main purpose of the present work is to optimize the performance of a selected turbine by establishing the optimal turbine’s design parameters. A complete analysis of the internal flow, which is of turbulent, two-phase and three dimensional in nature, was undertaken by simulating it using various CFD simulation codes. This study reports on the flow simulation using ANSYS CFX with a two-phase flow model, water-air free surface model and shear stress transport (SST) turbulence model. Prediction velocity and pressure fields of inside the turbine are, subsequently, used to characterize the turbine performance for different geometric parameters including the number of runner blades, the angle of attack, the ratio of inner to outer diameter, the nozzle profile, the blade profile, the nozzle throat width, the nozzle to runner blades width and the runner blades width to outer runner diameter. The results revealed the highly complex nature of the flow and provided a very good insight to the flow structure and performance optimization parameters.

This thesis investigates the relations between (1) free stream velocity, blade radius as well as the number of blades, and (2) generated torque, power and efficiency in the design of a water turbine. In the study, blade element momentum theory (BEMT) is exploited to devise the shape of the horizontal water turbine. Further, a CFD package is in used to simulate the flow and pressure fields. The result shows that torque and power generated by turbine vary with such parameters as inlet velocity and blade radii. As the number of blade increases, the generated power is also on the rise but to a lessened degree.It is due to the fact that fluid can hardly flow into the cross section as the blade number increases, which brings about lower cross-section velocity. So the rotational speed should decline as a consequence to obtain the angle of attack satisfying the greatest lift-drag ratio. The largest power efficiency is thus gained.

Ce travail porte sur la mise en œuvre de simulations sur des pales de machines tournantes. Une première partie de la thèse porte sur l’amélioration des performances du couplage fluide-structure. Des nouveaux algorithmes sont présentés. Une nouvelle méthode de déformation de maillage est évaluée. Les développements sont validés à partir de plusieurs cas tests. La deuxième partie porte sur l’application des avancées à des machines tournantes. Une première validation est faite sur une hydrolienne. La vibration d’une pale au passage du mat est étudiée. Enfin, des résultats sur une hydrolienne industrielle sont exposés. / A methodology to simulate blades of turbines is developed. A first part is dedicated to improving the performance of the fluid-structure coupling. New algorithms are presented. A new mesh morphing solution is shown. Developments are validated on many test cases. A second part is dedicated to applying the developments on turbines. A first validation is made on a water turbine. The vibration of a blade interacting with a mast is studied. Finally, some results of an industrial water turbine are shown.

This thesis aims to investigate the performance of a horizontal water turbine in ocean current. The design of the water turbine is based on the Blade Element Momentum theory to begin with. As the water current flows past a single turbine, the water inflow velocity and the rotational speed are the parameters to be investigated. Furthermore, the interaction of more than two turbines due to the relative distance is also discussed. The relative distance encompasses both the front and the back. The results show that the water inflow velocity and the turbine rotational speed influence the performance of the turbine. When two turbines function simultaneously, the flow field is different from the one of a single turbine and thus influences the performance of the other turbines in the vicinity. Lastly, the site arrangement of three turbines is discussed, and it is revealed that a proper arrangement can enhance the performance of the turbines.

In this thesis, the turbine blade design eligible for ocean current conditions is proposed using blade element momentum theory. in the beginning, the performance of water turbines is evaluated by CFD (computational fluid dynamics) package code, so as to design the suitable turbine under various conditions. The blade design encompasses parameters of the hydrofoil selection and blade shape which affect the turbine performance. Shortly following the investigation of the aforementioned parameters, the turbine¡¦s performance with radius of two meter is also studied. The current conditions include the yaw and the pitch angle of the turbine relative to the current flow direction, as well as the periodic flow conditions on the performance of the water turbine. Lastly, the electricity generation is estimated by the present device. The results show that hydrofoils with less changes in the angle of attack with respect to the lift-drag ratio help enhance the turbine¡¦s performance. The feedback mechanism is added to the blade design procedure to make sure that the turbine design caters to the best angle of attack. A turbine with two-meter radius can garner 34% of the sea current energy at most, living up to the project goal of exceeding the efficiency of 30%. The simulated test indicates that the adequate enlargement of the blade not only sustains the maximal efficiency, but it also lowers the stress imposed on the blade. Given the ocean current conditions, it is also shown that the turbine¡¦s efficiency is proportional to the cubic cosine incident angle of inflow velocity alongside with the enlargement of the turbine radius. When it comes to the current electricity generation, from the in-situ measurement data, the current maximal velocity near the sea region is around 1.3 m/s. If incorporated with the self excited induction generator with the efficiency of 55%, a one-meter-radius turbine is estimated to be able to generate 530W at most, while a two-meter-radius turbine is estimated to generate 2.5KW. However, the use of the permanent magnet generator can produce 45% more electricity than a self excited induction generator.

Cette thèse s'inscrit dans le cadre des énergies renouvelables au sein du programme HARVEST centré sur le développement d'un concept d'hydrolienne dérivé des turbines Darrieus et Gorlov. L'ajout d'un dispositif appelé carénage à la turbine permet à celle-ci d'extraire une portion de l'énergie cinétique du courant plus grande. Toutefois ce dernier peut favoriser la cavitation qui nuit à la turbine. Parmi les différents axes du programme, les travaux de thèse se situent dans cette problématique. En régime subcavitant et cavitant, l'analyse de l'hydrolienne a été menée suivant une approche numérique et expérimentale. Pour ce faire deux outils ont été mis en place. Du coté expérimental, le tunnel hydrodynamique du LEGI a été équipé d'une balance qui donne la mesure instantanée des forces et du couple qui s'exercent sur la turbine. Du coté numérique, les efforts ont été orientés sur l'amélioration et le développement du code de calcul universitaire, CAVKA. L'utilisation intensive de ces deux moyens, couplée à des modèles théoriques, a permis de mettre en évidence d'une part le fonctionnement de la turbine libre ou carénée et, d'autre part, les limites de fonctionnement vis-à-vis de la cavitation. / The general context of the present thesis is renewable energies within the HARVEST project, which consists in a water current turbine (WCT) development, inspired from the Darrieus and Gorlov geometries. The main advantage of the HARVEST WCT is the introduction of a channelling device, which allows extracting a bigger amount of the kinetic energy contained in the flowstream. However, the shrouding device can eventually increase cavitating risks, which generally damage the WCT itself and its performance. The main topic of this work is cavitation. The hydrodynamic behavior of the WCT is analyzed both numerically and experimentally, in non cavitating and cavitating conditions. For this analysis, two devices have been developed. On the one hand, the LEGI hydrodynamic channel is equipped with a measurement platform which provides the instantaneous and average measurements of two dimensional thrusts as well as the hydrodynamic torque. On the other hand, in the numerical domain, the work has been oriented to the improvement and the development of a CFD code, named Cavka. The intensive utilisation of these two devices, coupled to theoretical models, allow highlighting the functioning of the bare and shrouded WCTs and their limits in cavitating conditions.

Le but de cette thèse est le développement et l'optimisation de la chaine électrique d'une hydrolienne fluviale. L'approche est d'abord traitée en simulation pour ensuite finir par la conception et la mise au point d'un prototype. La partie simulation concerne la modélisation des ensembles turbines, génératrices et électronique de puissance mais aussi le développement des diverses lois de commandes. Ces commandes peuvent intervenir à différents niveaux du contrôle jusqu'à la supervision complète du système, permettant de gérer des défauts, des algorithmes de MPPT (extraction maximale de puissance), des synchronisations entre colonne, ... Le prototype d'hydrolienne fluviale sera ensuite présenté, de la mise au point des parties mécaniques jusqu'aux résultats expérimentaux. Les travaux nombreux autour de ce prototype ont permis d'obtenir des résultats satisfaisants et encourageants qui corroborent la théorie. / The purpose of this thesis is the development and optimization of the electrical system of a fluvial cross-flow current turbine. The approach is first treated in simulation and then eventually with the design and development of a prototype. The simulation section deals with the modeling of turbines groups, generators and power electronics, as well as the development of various control laws. These controls may have an influence at different levels of the control strategies up to the complete system supervision for fault management, MPPT (maximum power extraction) algorithms, turbine columns synchronization... The fluvial cross-flow current turbine prototype will then be presented, from the development of the mechanical parts to the experimental results. The various works involving the prototype have yielded satisfactory and encouraging results that corroborate the theory.

This diploma thesis deals with the design of the centrifugal switch of water turbine. The centrifugal switch is the security feature that stops the unit when the permitted unit speed is exceeded. In the first part of this thesis, the currently used types of centrifugal switches are described. This section deals also with the new centrifugal switch design and dynamics analysis of individual switch pins.

L'exploitation de l'énergie cinétique des courants marins ou fluviaux est une source d'énergie prometteuse et renouvelable. Les performances hydrodynamiques des hydroliennes sont à ce jour bien connues et l'attention se porte sur la compréhension des phénomènes de parc et l'interaction entre machines. Ce document présente la construction d'un modèle simplifié (ou méthode d'équivalence) pour les turbines à axe de rotation vertical. Une étape préliminaire consiste à valider l'utilisation de la méthode de maillage rotatif proposée par Code_Saturne (solveur CFD open source). La simulation de la turbine Darrieus/Achard A10 en 2D met en évidence une bonne concordance des mesures expérimentales (PIV). Cet outil sert dans une seconde étape à mettre au point un modèle simplifié de ces mêmes turbines. Celui-ci consiste à représenter la turbine dans l'écoulement par son équivalent en termes sources de quantité de mouvement sur la base d'une paramétrisation efficace des données empiriques. La méthode est validée pour une large plage de vitesses de rotation et de confinements, et sur plusieurs machines. La représentation du sillage par par les deux méthode de simulation est ensuite étudiée en détail. Des mesures par la technique de LDV dans le sillage proche d'un modèle réduit sont effectuées et établissent une référence expérimentale nécessaire pour ce type de machine. La dépendance forte des deux méthodes de simulation aux paramètres et aux modèles de turbulence est constatée. Deux phénomènes principaux sont relevés : la diffusion turbulente et les instabilités à grandes échelles. Des calculs de rendement sur des dispositions de machines variables illustrent l'applicabilité du modèle. Ils mettent notamment en avant l'effet positif de l'intensité turbulente ambiante sur le rendement dans un parc. / Harnessing kinetic energy from oceans or rivers is a promising source of renewable energy. The hydrodynamical performance of water turbines is well known and the focus is now on array optimization and turbine interaction. The present document aims to introduce a new modeling solution for vertical axis water current turbine of Darrieus/Achard type and its construction methodology. A preliminary stage consists in the validation of the new sliding mesh method available in Code_Saturne, EDF CFD open source solver. The good results obtained by comparison with PIV measurements on the Achard type turbine allow the use of this method as a reference tool. The second stage sees the construction of an equivalence model for the Darrieus turbine using momentum source terms. These terms are calculated thanks to an efficient parametrization of empirical data. The comparison of the model with full geometry calculation shows a good agreement in terms of power for a wide range of rotational velocity and blocking ratio. LDV measurements in the near wake of a small scale Achard turbine give a necessary reference set of data. The wake given by both simulations is strongly dependent of turbulence parameters or models, with the cohabitation of two main phenomena : momentum turbulent diffusion, and large scale fluctuations. To conclude, a calculation of the power output for several turbine distributions in an array illustrates the model capability.

This master’s thesis deals with the feasibility study of the pumped-storage hydropower plant. Design is divided at three parts – upper water-reservoir with water intake, penstock with cabel tunnel and mechanical room with four Francis reversible turbine. Study contains engineering report, hydraulic calculations, photodocumentation and drawing documentation.