Download or read book Oscillating foils Hydrokinetic Turbine Performance Prediction written by Étienne Gauthier and published by . This book was released on 2015 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: This master's thesis focuses on a novel prototype of hydrokinetic turbine based on oscillating foils. This concept known as HAO, which stands for "Hydrolienne à Ailes Oscillantes", has been under development for about 10 years at Laval University and its potential in power extraction has been confirmed through numerical and experimental studies. Efforts are now focused on developing tools to predict the turbines behavior prior to its deployment in rivers or tidal streams. To achieve this goal, computational fluid dynamics (CFD) is used to investigate the impact of different parameters on the power-extraction performance of the HAO turbine. This study describes, among other things, the influence of the turbulence modeling, the presence of the frame structure and the blockage effects. First of all, a methodological study performed on a single oscillating foil is presented which compares two different turbulence modeling approaches. This work has shown that even if the Scale-Adaptive Simulation model presents finer structures in the wake of the foil, instantaneous forces and mean performance parameters closely match the results obtained with the Spalart-Allmaras model which is thus used to simulate the complete HAO hydrokinetic turbine prototype. In a second study, the HAO hydrokinetic turbine is simulated considering two hydrofoils oscillating within the frame structure. The overset mesh technique is used to represent the relative motions of the different bodies. This methodology allows to study the impact of the frame structure on the turbine performance and to optimize its shape in order to increase the power extracted. In addition to the enhanced performances, the optimized frame shape provides an improved robustness to misaligned upstream flows. The third principal aspect addressed in this thesis is the impact of flow confinement on the performance of oscillating-foils. In fact, towing tank walls, sea and river bed topology and free surface proximity are likely to have an impact on the turbine hydrodynamic performance. Simulations of a single oscillating foil for different blockage levels have shown that the power extracted increases with the blockage ratio, but more precisely that this relation is linear for confinement of less than 40%. Finally, a technique is suggested to correlate the performance of the oscillating-foils turbines in different confined environments.
Download or read book Vortex Dynamics and Machine Learning on Oscillating foil Turbines written by Bernardo Luiz Rocha Ribeiro (Ph.D.) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oscillating foils in a combined heave/pitch motion are an effective way to extract hydrokinetic energy and offer benefits of shallow water operation, scalability, and low cut-in speeds. In a flapping-foil turbine, power generation is a function of the foil kinematics, namely operating foil frequency, heave, and pitch amplitude. The efficiency and kinematics of a single foil in freestream conditions are well understood both numerically and experimentally, however foils in coordinated array configurations have not received as much attention. As observed in other wind and hydrokinetic turbines, the downstream foils of arrays suffer from reduced freestream velocity and wake disturbances. Thus, a major challenge within the industry is to accurately predict and model how the wake of one turbine affects the others downstream. Progress has been made in wind farm layouts, however due to the oscillatory, rather than rotational, kinematics the wake structure of oscillating foils is vastly different from that of traditional horizontal-axis turbines. This thesis first revisits single-foil turbines and analyze the Reynolds number effects on the energy harvesting. It is found that comparing data between Re=50,000 and Re=1000, the high Reynolds number flows demonstrated a moderate 0.8 - 6.7% increase in power compared to the low Reynolds number flow. Using data from experiments and simulations, an in-depth wake analysis is performed and the mean velocity and the turbulent kinetic energy are quantified in the wake. With the mean wake velocity, a predictive wake model is able to distinguish three regimes through analyzing trailing foil efficiency profiles. Using machine learning algorithms, further investigation is made on the wake from those three regimes of foil kinematics and wake patterns are distinguished with respect to the foil parameters. Lastly, a power prediction model is developed based on the effects of vortex-foil interactions in two-foil arrays and can be used to predict array performance at different configurations only using single-foil data.
Download or read book Analysis Optimization and Demonstration of a New Concept of Hydrokinetic Turbine Based on Oscillating Hydrofoils written by Thomas Kinsey and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of the Sweep Angle on the Leading Edge Vortex and Its Relation to the Power Extraction Performance of a Fully passive Oscillating plate Hydrokinetic Turbine Prototype written by Waltfred Lee and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Oscillating-foil hydrokinetic turbines have gained interest over the years to extract energy from renewable sources. The influence of the sweep angle on the performance of a fully-passive oscillating-plate hydrokinetic turbine prototype was investigated experimentally in the present work. The sweep angle was introduced to promote spanwise flow along the plate in order to manipulate the leading edge vortex (LEV) and hydrodynamically optimize the performance of the turbine. In the present work, flat plates of two configurations were considered: a plate with a 6° sweep angle and an unswept plate (control), which were undergoing fully-passive pitch and heave motions in uniform inflow at the Reynolds numbers ranging from 15 000 to 30 000. The resulting kinematic parameters and the energy extraction performance were evaluated for both plates. Planar (2D) particle image velocimetry (PIV) was used to obtain patterns of the phase-averaged out-of-plane vorticity during the oscillation cycle. The circulation in the wake was then related to the induced-forces on the plate by calculating the moments of vorticity of the LEV with respect to the pitching axis of the plate. Tomographic (3D) PIV was implemented in evaluating the influence of the spanwise flow on the dynamics of the vortex structure in three-dimensional space. The rate of deformation of the vortex length was quantified by calculating the deformation terms embedded in the vorticity equations, then linked to the stability of the vortex. The results show evidence of delay of the shedding of LEV and increased vortex stability, in the case of the swept plate. The manipulation of the LEV by the spanwise flow was related to the induced kinematics exhibited by the prolonged heave forces experienced by the swept plate, which led to the higher power extraction performance at high inflow velocities. In the presence of spanwise flow, positive vortex stretching along the vortex line increased the stabilization of the vortex core and prevented the onset of helical vortex breakdown, observed in the case of the unswept plate. The use of the sweep profile on the plate has led to the improvement of energy extraction performance of the fully-passive hydrokinetic turbine.
Download or read book Experimental Investigation of Oscillating foil Technologies written by Dylan Iverson and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis contains an experimental campaign on the practical implementation of oscillating-foil technologies. It explores two possible engineering applications of oscillating-wings: thrust-generation, and energy-extraction. The history of, benefits of, and difficulties involved in the use of oscillating-foils is discussed throughout. Many existing technologies used for thrust generation and hydrokinetic energy extraction are based on rotating blades or foils, which have evolved over decades of use. In recent years, designs that use oscillating-foils, with motions analogous to the flapping of a fish's tail or a bird's wing, have shown increased hydrodynamic performance compared to the traditional rotary technologies. However, these systems are complex, both in terms of the governing unsteady fluid dynamics, and the methods by which kinematics are prescribed. Simply put, system complexity and cost need to be reduced before these devices see wide-spread use. For this reason, the work contained within this thesis explores possible methods of reducing the complexity of oscillating-foil systems in an effort to contribute to their development. For thrust-generation applications, this entailed using flexible foils to create passive pitching kinematics. This was parametrically studied by testing foils of different structural properties under a range of kinematics. The results suggested that properly tuning the flexibility of the foil could enhance both the thrust generation, and the efficiency of the propulsive system. With respect to energy-harvesting applications, the reliability of a novel fully passive turbine was assessed. The prototype tested had no active control strategy, and the degreesof-freedom were not mechanically linked, greatly simplifying the design. The prototype was subjected to real-world conditions, including high turbulence levels and the wake of an upstream turbine, and displayed robust performance in most conditions. In both applications, the hydrodynamic performance of the oscillating-wings was directly measured, and particle image velocimetry was used to observe the flow topology in the wakes and boundary layers of the foils. The vortex and stall dynamics were highlighted as key flow features, and are studied in detail.
Download or read book Advances in Critical Flow Dynamics Involving Moving Deformable Structures with Design Applications written by Marianna Braza and published by Springer Nature. This book was released on 2021-02-10 with total page 599 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports on the latest knowledge concerning critical phenomena arising in fluid-structure interaction due to movement and/or deformation of bodies. The focus of the book is on reporting progress in understanding turbulence and flow control to improve aerodynamic / hydrodynamic performance by reducing drag, increasing lift or thrust and reducing noise under critical conditions that may result in massive separation, strong vortex dynamics, amplification of harmful instabilities (flutter, buffet), and flow -induced vibrations. Theory together with large-scale simulations and experiments have revealed new features of turbulent flow in the boundary layer over bodies and in thin shear layers immediately downstream of separation. New insights into turbulent flow interacting with actively deformable structures, leading to new ways of adapting and controlling the body shape and vibrations to respond to these critical conditions, are investigated. The book covers new features of turbulent flows in boundary layers over wings and in shear layers immediately downstream: studies of natural and artificially generated fluctuations; reduction of noise and drag; and electromechanical conversion topics. Smart actuators as well as how smart designs lead to considerable benefits compared with conventional methods are also extensively discussed. Based on contributions presented at the IUTAM Symposium “Critical Flow Dynamics involving Moving/Deformable Structures with Design applications”, held in June 18-22, 2018, in Santorini, Greece, the book provides readers with extensive information about current theories, methods and challenges in flow and turbulence control, and practical knowledge about how to use this information together with smart and bio-inspired design tools to improve aerodynamic and hydrodynamic design and safety.
Download or read book Internet of Things Smart Spaces and Next Generation Networks and Systems written by Yevgeni Koucheryavy and published by Springer Nature. This book was released on 2023-04-19 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the joint refereed proceedings of the 22nd International Conference on Internet of Things, Smart Spaces, and Next Generation Networks and Systems, NEW2AN 2022, held in Tashkent, Uzbekistan, in December 2022. The 58 regular papers presented in this volume were carefully reviewed and selected from 282 submissions. The papers of NEW2AN address various aspects of next-generation data networks, while special attention is given to advanced wireless networking and applications. In particular, the authors have demonstrated novel and innovative approaches to performance and efficiency analysis of 5G and beyond systems, employed game-theoretical formulations, advanced queuing theory, and machine learning. It is also worth mentioning the rich coverage of the Internet of Things, optics, signal processing, as well as digital economy and business aspects.
Download or read book An Evaluation of the U S Department of Energy s Marine and Hydrokinetic Resource Assessments written by National Research Council and published by National Academies Press. This book was released on 2013-04-23 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing renewable energy development, both within the United States and abroad, has rekindled interest in the potential for marine and hydrokinetic (MHK) resources to contribute to electricity generation. These resources derive from ocean tides, waves, and currents; temperature gradients in the ocean; and free-flowing rivers and streams. One measure of the interest in the possible use of these resources for electricity generation is the increasing number of permits that have been filed with the Federal Energy Regulatory Commission (FERC). As of December 2012, FERC had issued 4 licenses and 84 preliminary permits, up from virtually zero a decade ago. However, most of these permits are for developments along the Mississippi River, and the actual benefit realized from all MHK resources is extremely small. The first U.S. commercial gridconnected project, a tidal project in Maine with a capacity of less than 1 megawatt (MW), is currently delivering a fraction of that power to the grid and is due to be fully installed in 2013. As part of its assessment of MHK resources, DOE asked the National Research Council (NRC) to provide detailed evaluations. In response, the NRC formed the Committee on Marine Hydrokinetic Energy Technology Assessment. As directed in its statement of task (SOT), the committee first developed an interim report, released in June 2011, which focused on the wave and tidal resource assessments (Appendix B). The current report contains the committee's evaluation of all five of the DOE resource categories as well as the committee's comments on the overall MHK resource assessment process. This summary focuses on the committee's overarching findings and conclusions regarding a conceptual framework for developing the resource assessments, the aggregation of results into a single number, and the consistency across and coordination between the individual resource assessments. Critiques of the individual resource assessment, further discussion of the practical MHK resource base, and overarching conclusions and recommendations are explained in An Evaluation of the U.S. Department of Energy's Marine and Hydrokinetic Resource Assessment.
Download or read book Cavitation and Bubble Dynamics written by Christopher E. Brennen and published by Cambridge University Press. This book was released on 2014 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cavitation and Bubble Dynamics deals with fundamental physical processes of bubble dynamics and cavitation for graduate students and researchers.
Download or read book Aerodynamics of Wind Turbines 2nd edition written by Martin O. L. Hansen and published by Routledge. This book was released on 2013-05-13 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The new material includes a description of the effects of the dynamics and how this can be modelled in an ?aeroelastic code?, which is widely used in the design and verification of modern wind turbines. Further, the description of how to calculate the vibration of the whole construction, as well as the time varying loads, has been substantially updated.
Download or read book Ocean Wave Energy written by Joao Cruz and published by Springer Science & Business Media. This book was released on 2007-12-22 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors of this timely reference provide an updated and global view on ocean wave energy conversion – and they do so for wave energy developers as well as for students and professors. The book is orientated to the practical solutions that this new industry has found so far and the problems that any device needs to face. It describes the actual principles applied to machines that convert wave power to electricity and examines state-of-the-art modern systems.
Download or read book Wave and Tidal Energy written by Deborah Greaves and published by John Wiley & Sons. This book was released on 2018-03-28 with total page 717 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eine umfassende Publikation zu sämtlichen Aspekten der Wellen- und Gezeitenenergie. Wave and Tidal Energy gibt einen ausführlichen Überblick über die Entwicklung erneuerbarer Energie aus dem Meer, bezieht sich auf die neueste Forschung und Erfahrungen aus Anlagentests. Das Buch verfolgt zwei Ziele, zum einen vermittelt es Einsteigern in das Fachgebiet eine Überblick über die Wellen- und Gezeitenenergie, zum anderen ist es ein Referenzwerk für komplexere Studien und die Praxis. Es vermittelt Detailwissen zu wichtigen Themen wie Ressourcencharakterisierung, Technologie für Wellen- und Gezeitenanlagen, Stromversorgungssysteme, numerische und physikalische Modellierung, Umwelteffekte und Politik. Zusätzlich enthält es eine aktuelle Übersicht über Entwicklungen in der ganzen Welt sowie Fallstudien zu ausgewählten Projekten. Hauptmerkmale: - Ausführliches Referenzwerk zu allen Aspekten der interdisziplinären Fachrichten Wellen- und Gezeitenenergie. - Greift auf die neuesten Forschungsergebnisse und die Erfahrung führender Experten in der numerischen und laborgestützten Modellierung zurück. - Gibt einen Überblick über regionale Entwicklungen in aller Welt, repräsentative Projekte werden in Fallstudien vorgestellt. Wave and Tidal Energy ist ein wertvolles Referenzwerk für eine breite Leserschaft, von Studenten der Ingenieurwissenschaften und technischen Managern über politische Entscheidungsträger bis hin zu Studienabsolventen und Forschern.
Download or read book Improved Two Equation K Omega Turbulence Models for Aerodynamic Flows written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-18 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two new versions of the k-omega two-equation turbulence model will be presented. The new Baseline (BSL) model is designed to give results similar to those of the original k-omega model of Wilcox, but without its strong dependency on arbitrary freestream values. The BSL model is identical to the Wilcox model in the inner 50 percent of the boundary-layer but changes gradually to the high Reynolds number Jones-Launder k-epsilon model (in a k-omega formulation) towards the boundary-layer edge. The new model is also virtually identical to the Jones-Lauder model for free shear layers. The second version of the model is called Shear-Stress Transport (SST) model. It is based on the BSL model, but has the additional ability to account for the transport of the principal shear stress in adverse pressure gradient boundary-layers. The model is based on Bradshaw's assumption that the principal shear stress is proportional to the turbulent kinetic energy, which is introduced into the definition of the eddy-viscosity. Both models are tested for a large number of different flowfields. The results of the BSL model are similar to those of the original k-omega model, but without the undesirable freestream dependency. The predictions of the SST model are also independent of the freestream values and show excellent agreement with experimental data for adverse pressure gradient boundary-layer flows. Menter, Florian R. Ames Research Center RTOP 505-59-40...
Download or read book Wind Turbines written by Erich Hau and published by Springer Science & Business Media. This book was released on 2005-12-12 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind Turbines addresses all those professionally involved in research, development, manufacture and operation of wind turbines. It provides a cross-disciplinary overview of modern wind turbine technology and an orientation in the associated technical, economic and environmental fields. It is based on the author's experience gained over decades designing wind energy converters with a major industrial manufacturer and, more recently, in technical consulting and in the planning of large wind park installations, with special attention to economics. The second edition accounts for the emerging concerns over increasing numbers of installed wind turbines. In particular, an important new chapter has been added which deals with offshore wind utilisation. All advanced chapters have been extensively revised and in some cases considerably extended
Download or read book Wind Energy in the Built Environment written by Sander Mertens and published by Multi-Science Publishing Company. This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the wind resources in the built environment that can be converted into energy by a wind turbine. It especially deals with the integration of a wind turbine and a building in such a way that the building concentrates the available wind energy for the wind turbine. The three different ways to concentrate wind power are examined: wind turbines on the roof or at the sides of a building; wind turbines between two airfoil shaped buildings; wind turbines in ducts through buildings.
Download or read book Energy Harvesting written by Alireza Khaligh and published by CRC Press. This book was released on 2017-12-19 with total page 529 pages. Available in PDF, EPUB and Kindle. Book excerpt: Also called energy scavenging, energy harvesting captures, stores, and uses "clean" energy sources by employing interfaces, storage devices, and other units. Unlike conventional electric power generation systems, renewable energy harvesting does not use fossil fuels and the generation units can be decentralized, thereby significantly reducing transmission and distribution losses. But advanced technical methods must be developed to increase the efficiency of devices in harvesting energy from environmentally friendly, "green" resources and converting them into electrical energy. Recognizing this need, Energy Harvesting: Solar, Wind, and Ocean Energy Conversion Systems describes various energy harvesting technologies, different topologies, and many types of power electronic interfaces for stand-alone utilization or grid connection of energy harvesting applications. Along with providing all the necessary concepts and theoretical background, the authors develop simulation models throughout the text to build a practical understanding of system analysis and modeling. With a focus on solar energy, the first chapter discusses the I−V characteristics of photovoltaic (PV) systems, PV models and equivalent circuits, sun tracking systems, maximum power point tracking systems, shading effects, and power electronic interfaces for grid-connected and stand-alone PV systems. It also presents sizing criteria for applications and modern solar energy applications, including residential, vehicular, naval, and space applications. The next chapter reviews different types of wind turbines and electrical machines as well as various power electronic interfaces. After explaining the energy generation technologies, optimal operation principles, and possible utilization techniques of ocean tidal energy harvesting, the book explores near- and offshore approaches for harvesting the kinetic and potential energy of ocean waves. It also describes the required absorber, turbine, and generator types, along with the power electronic interfaces for grid connection and commercialized ocean wave energy conversion applications. The final chapter deals with closed, open, and hybrid-cycle ocean thermal energy conversion systems.
Download or read book Marine Propellers and Propulsion written by John Carlton and published by Butterworth-Heinemann. This book was released on 2012-10-30 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: The early development of the screw propeller. Propeller geometry. The propeller environment. The ship wake field, propeller performance characteristics.
