Idénergie develops the first domestic hydrokinetic turbine for rivers. Itaims at producing about 100W in a 1.4m/s river to power up remote locations.Idénergie’s turbine has two main advantages: a completely watertight shaftlessgenerator and an integrated smart converter. The first turbines are planned tobe sold in June 2014.To be able to test the embedded intelligence in the lab, Idénergie’s testbench must be able to reproduce river conditions. Measurements have beenperformed in a river and provide the torque developed by the river at differentspeeds. On the test bench controlled by a LabView program, the rotationalspeed is measured and the corresponding torque computed. This torque is setas the new command and makes the test bench behave as if it was driven by aturbine in a river.Idénergie’s generator contains a rotor made of permanent magnets.These magnets are provided by a supplier and their quality needs to bechecked. For this purpose, a magnetometer is designed and built. It contains 5Hall effect sensors which move at a constant speed above a magnet andmeasure its magnetic field. The magnetometer is able to compare magnets to areference and to detect the faulty ones. The sensors are also used to measurethe magnetic field of the rotor and show that the custom-made shape of themagnets has no influence on the sinusoidal field.The converter transforms the three-phase current to direct current andcontrols the rotational speed. This is done thanks to an embedded electroniccard, which is about to be working properly. The Maximum Power PointTracking algorithm ensures that the rotational speed is optimum in order toproduce the maximum power output. The code loaded on this card is written inits main part but needs to be tested on the test bench once the card will beoperational.

Many people around the world still lack access to a reliable electricity grid. Supplying electricity to remote off grid areas like villages around Leticia, Colombia is often interrelated with high costs and geographical limitations. Today most of the electricity demand is met through the usage of diesel generators. The generators are easy to use and have a relatively reliable functionality. However, fuel is expensive and there are other negative aspects as fumes and sound pollution. In order to provide a cleaner, more reliable and cost efficient alternative the company Jabe Energy AB has in cooperation with the volunteer organization Ankarstiftelsen developed a new type of hydrokinetic turbine (slow moving none damming turbine). Previous studies have shown that there is potential for hydrokinetic turbines to increase their power output simply by their relative placement (coupling potential). That is, it might be possible to extrude more power from a system where two hydrokinetic turbines are placed in a close relation rather than being completely separated. Since the turbine investigated is newly developed there have been no previous studies regarding its specific coupling potential. To investigate this potential given the conditions in the Amazon basin, a field study is conducted where measurements on water velocity at different heights in the water column is collected. The data is later used as input conditions for a turbine model developed in the program COMSOL. The aim is to use simulations in order to determine whether a turbine is sensitive for its relative placement to a former (coupling potential) and furthermore to investigate a possible optimal turbine coupling position. The results will show that the turbine is coupling sensitive and that there exists more advantageous placements. Comparing the best and worst case of the coupling study displays an 11.87% difference in possible energy output. The conclusion is that further empirical studies are necessary in order to validate the results. Finally a suggestion on how these studies should be conducted is presented and discussed.

This thesis focuses on generating real world turbulence levels in a water tunnel rotor test using fractal grids and characterizing the effect of the fractal grid generated-turbulence on the performance of hydrokinetic turbines. The research of this thesis is divided into three studies: one field study and two laboratory studies. The field study was conducted at the Canadian Hydro Kinetic Turbine Test Centre (CHTTC) on the Winnipeg River. An Acoustic Doppler Velocimeter (ADV) was used in the field study to collect flow measurements in the river. The laboratory studies were conducted at the University of Victoria (UVic) fluids research lab and the Sustainable Systems Design Lab (SSDL). In addition, the Particle Image Velocimetry (PIV) technique was used in the experiential studies to obtain quantitative information about the vector flow field along the test section, both upstream and downstream of the rotor’s plane. The first study is a field study aiming to provide real flow characteristics and turbulence properties at different depths from the free-surface to boundary layer region of a fast river current by conducting a field study in the Winnipeg River using ADV. A novel technique to deploy and control an ADV from free-surface to boundary layer in a fast-current channel is introduced in this work. Flow characteristics in the river, including mean flow velocities and turbulence intensity profiles are analyzed. The obtained results indicate that the maximum mean velocity occurs below the free-surface, suggesting that the mean velocity is independent of the channel depth. From the free-surface to half depth, it was found that changes in both the mean velocity and turbulence intensity are gradual. From mid-depth to the river bed, the mean velocity drops rapidly while the turbulence intensity increases at a fast rate. The turbulent intensity varied from 9% at the free-surface to around 17.5% near the river bed. The results of this study were used in the second lab study to help designing a fractal grid for a recirculating water flume tank. The goal was to modify the turbulence intensity in the water tunnel such that the generated turbulence was similar to that in the river at a location typical of a hydrokinetic device. The properties of fractal-generated turbulence were experimentally investigated by means of 2D Particle Image Velocimetry (PIV). The streamwise turbulent intensity profiles for different grids along the channel are presented. Additionally, visualization of the average and fluctuating flow fields are also presented. The results are in good agreement with results in literature. The third and final study investigated the power coefficient of a scale hydrokinetic turbine rotor in controlled turbulent flow (7.4 % TI), as well as in the low-turbulence smooth flow (0.5% TI) typical of lab scale testing. PIV was employed for capturing the velocity field. The results show that using realistic TI levels in the water tunnel significantly decrease the turbine’s power coefficient compared to smooth flow, highlighting the importance of considering this effect in future experimental campaigns. / Graduate

The predictive capabilities of blade-resolved unsteady Reynolds averaged Navier-Stokes (URANS) and detached eddy simulation (DES), the most commonly used hybrid RANS/large eddy simulation (LES) model, are assessed for hydrokinetic turbine performance and mean and turbulent flows in the intermediate-wake region, and results for a range of tip-speed ratio encompassing design and off-design conditions are analyzed to understand the wake recovery mechanism. The performance predictions compared within 5% of the experimental data. Both URANS and DES models performed reasonably well for the near wake predictions, where the errors were < 15%. DES outperformed URANS for both mean wake deficit and turbulence predictions in the intermediate-wake region and both quantities compared within 10% of the experiments. The improved prediction by DES is because of 1) its ability to predict the tip vortex breakdown, which plays a critical role in the wake recovery, especially for higher tip speed ratios; 2) the presence of the free-surface which created an upper bypass region of accelerated flow. The study reveals that the tip vortex breakdown mechanism depends on tip speed ratio. For lower values of tip speed ratio, instabilities generated in the root vortex core are identified to be the cause of breakdown. For higher values, the breakdown occurred because of the instabilities generated during the vortex filament entanglement. The presence of the free-surface led to an early vortex breakdown and the interaction between the wake and free-surface is initiated by the interaction of stanchion with the free-surface. Future work should focus on investigation of other hybrid RANS/LES models to address the limitations of the DES models, and extension of the study to include wave effects.

Dans le cadre de la production d'électricité par énergie renouvelable, cette thèse a pour objectif de contribuer à l'amélioration des performances hydrodynamiques des hydroliennes à flux transverse conçues par HydroQuest. Pour y parvenir, deux axes d'étude principaux sont proposés. Le premier consiste à améliorer la compréhension de la performance de l'hydrolienne et de l'écoulement en son sein par voie numérique. L'influence du paramètre d'avance ainsi que celle de la solidité de l'hydrolienne sont étudiées. Les écoulements mis en jeux étant complexes, une méthode de type Simulation des Granges Échelles 3D est utilisée afin de les restituer au mieux. Le phénomène de décrochage dynamique, qui apparaît pour certains régimes de fonctionnement de l'hydrolienne, fait l'objet d'une étude à part entière sur un cas de profil oscillant.Le second axe se concentre sur les carénages de l’hydrolienne qui font l'objet d'une procédure d'optimisation numérique. Afin de pouvoir réaliser les nombreuses simulations requises en un temps réaliste, des méthodes de type Unsteady Reynolds-Averaged Navier-Stokes 2D moins coûteuses et fournissant une précision suffisante pour ce type d'étude sont utilisées. / Within the renewable electricity production framework, this study aims to contribute to the efficiency improvement of the Vertical Axis Hydrokinetic Turbines designed by HydroQuest. To achieve this objective, two approaches are used. The first consists in the improvement of the comprehension of the turbine efficiency such as the flow through the turbine by numerical means. The influence of the tip speed ratio such as the turbine soldity are investigated. The flow through the turbine is complex. A 3D Large Eddy Simulation type is thus used. The dynamic stall phenomenon which could occur in Vertical Axis Hydrokinetic Turbines is also studied in a oscillating blade configuration.The second approach consists in the numerical optimization of the turbine channeling device. To perform the high number of simulations required, a 2D Unsteady Reynolds-Averaged Navier-Stokes simulation type is used.

<p>This thesis proposes the design and documents analysis for a Modular River Current Energy Converter (MRCEC) to improve the efficiency of hydrokinetic turbine power systems. The MRCEC can produce electricity from low-velocity river flow with increased energy affordability and availability. The MRCEC, for the scope of this thesis, consists of the hydroturbine and maintenance systems. The turbine in the MRCEC system is a cross-flow cycloidal turbine that yields a high power coefficient (0.515) through a novel pitch variance mechanism involving a 3D cam that adapts to varying river flow conditions to maximize operational efficiencies. The cycloidal turbine is a four-section three-blade turbine that uses a unique hydrofoil profile designed for the MRCEC. The cycloidal turbine is housed in a frame supported by a flotation system to harness energy from near-surface currents. The flotation system, in turn, is connected to the service dock which houses the mooring, debris blockage, and maintenance systems. The mooring system allows the MRCEC to be fixed at the working site while allowing for self-adjustment with varying river depths. The debris blockage system prevents debris carried by the river from interfering with an operational hydroturbine. The maintenance system enables the installation, operation, and maintenance functions by integrating a flipping mechanism to invert the turbine for transportation and maintenance purposes. Mechanisms of these systems are designed to appropriate standards, then simulated to validate functionality at all stages of installation, operation, and maintenance.</p>

La récupération, grâce aux hydroliennes, de l’énergie cinétique de courants marins et fluviaux constitue une source d’énergie renouvelable considérable et prédictible. La simulation fine, par une description statistique instationnaire de type URANS, de l’écoulement autour d’une hydrolienne isolée à axe vertical, bi-rotor et munie d’un carénage (hydrolienne de type HARVEST) donne accès à une estimation précise de la puissance produite. Cependant, le coût élevé de cette approche URANS la rend inadaptée à la simulation d’un parc de machines. Une analyse de la littérature conduit à retenir un modèle basse-fidélité de type Blade Element Momentum (BEM) pour décrire à moindre coût l’effet du rotor de la turbine sur l’écoulement, dans le contexte d’une description 2D (coupe horizontale). La performance de l’hydrolienne est alors prédite par un calcul RANS incluant des termes sources distribués dans un anneau rotor virtuel et conservant le maillage des parties fixes (carénage). Ces termes sources sont construits grâce à une procédure originale exploitant les conditions locales de l’écoulement en amont des cellules du rotor virtuel et le débit de l’écoulement traversant l’hydrolienne. Les coefficients hydrodynamiques utilisés pour le calcul des termes sources BEM-RANS sont construits une fois pour toutes en exploitant une série de simulations URANS préliminaires ; ils intègrent les effets du carénage et le fonctionnement de chaque rotor à une vitesse de rotation optimale (maximisant la puissance produite) grâce au système de régulation de l’hydrolienne. Le modèle BEM-RANS développé est validé par comparaison avec des simulations URANS de référence : il fournit une estimation fiable de la puissance produite (erreur de quelques % par rapport à l’approche URANS) pour un coût réduit de plusieurs ordres de grandeur. Ce modèle est appliqué à l'analyse de la puissance produite par une rangée d’hydroliennes HARVEST dans un canal pour différents facteurs de blocage et d’espacement latéral ainsi qu’à une ferme marine composée de trois hydroliennes. / The capture, thanks to hydrokinetic turbines, of the kinetic energy generated by sea and river currents provides a significant and predictable source of renewable energy. The detailed simulation, using an unsteady statistical description of URANS type, of the flow around an isolated water turbine of HARVEST type (cross flow vertical axis ducted water turbine) provides an accurate estimate of the power output. However, the cost of the URANS approach is much too expensive to be applied to a farm of several turbines. A review of the literature leads to select a low-fidelity model of Blade Element Momentum (BEM) type to describe at a reduced cost the rotor effect on the flow, in a 2D context (horizontal cross-section). The turbine performance is then predicted using a steady RANS simulation including source terms distributed within a virtual rotor ring and preserving the mesh of the turbine fixed parts (duct). These source terms are derived using an original procedure which exploits both the local flow conditions upstream of the virtual rotor cells and the flow rate through the turbine. The hydrodynamic coefficients used to compute the BEM-RANS source terms are built once for all from a series of preliminary URANS simulations; they include the effects of the duct on the flow and the rotor operating at optimal rotational speed (maximizing the power output) thanks to the turbine regulation system. The BEM-RANS model is validated against reference URANS simulations: it provides a reliable prediction for the power output (within a few % of the URANS results) at a computational cost which is lowered by several orders of magnitude. This model is applied to the analysis of the power produced by a row of Vertical Axis Water Turbines in a channel for various values of the blockage ratio and lateral spacing as well as to a 3-machine sea farm.

This study presents a numerical investigation of ducted tidal turbines, employing three-dimensional Reynolds-averaged Navier-Stokes simulations. Bidirectional ducted turbines are modelled with and without aperture, referred to as ducted and open- centre turbines respectively. The work consists of two investigations. In the first, the turbine rotors are represented by actuator discs, a simplification which captures changes in linear momentum and thus the primary interaction of the turbine with the flow through and around the duct, while greatly reducing computational complexity. In the second investigation, the turbine rotors are represented through a CFD-integrated blade element momentum model, employing realistic rotor data, capturing swirl and blade drag in addition to the extraction of linear momentum. Both modelling techniques were employed to investigate the performances of bare, ducted, and open-centre turbines, relating these to the flow fields exhibited. For axial flow, substantial decreases in power generated by the ducted and open-centre turbines were found, relative to a bare turbine of equal total device diameter. For open-centre turbines, an increase in aperture size leads to a further reduction in power generated. Increased blockage was shown to positively affect the performance of all devices. Two further measures of performance were employed: power density, normalising the power by the rotor area, and basin efficiency, relating the power generated to the overall power removed from the flow. Moderate increases in power density can be achieved for the ducted and open-centre devices, while their basin efficiencies are of similar value to that of the bare turbine. For yawed inflow, the performance of the bare turbine decreases, whilst that of the ducted and open-centre turbines increases. This is due to an increased flow velocity following flow acceleration around the inlet lip of the duct and also an increase in effective blockage as ducts present greater projected frontal area when approached non-axially.