Challenges In Simulation Of Aerodynamics Hydrodynamics And Mooring Line Dynamics Of Floating Offshore Wind Turbines
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Challenges In Simulation Of Aerodynamics Hydrodynamics And Mooring Line Dynamics Of Floating Offshore Wind Turbines
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Author :
language : en
Publisher:
Release Date : 2011
Challenges In Simulation Of Aerodynamics Hydrodynamics And Mooring Line Dynamics Of Floating Offshore Wind Turbines written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
This paper presents the current major modeling challenges for floating offshore wind turbine design tools and describes aerodynamic and hydrodynamic effects due to rotor and platform motions and usage of non-slender support structures.
Mooring Line Modelling And Design Optimization Of Floating Offshore Wind Turbines
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Author : Matthew Thomas Jair Hall
language : en
Publisher:
Release Date : 2013
Mooring Line Modelling And Design Optimization Of Floating Offshore Wind Turbines written by Matthew Thomas Jair Hall and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Floating offshore wind turbines have the potential to become a significant source of affordable renewable energy. However, their strong interactions with both wind- and wave-induced forces raise a number of technical challenges in both modelling and design. This thesis takes aim at some of those challenges. One of the most uncertain modelling areas is the mooring line dynamics, for which quasi-static models that neglect hydrodynamic forces and mooring line inertia are commonly used. The consequences of using these quasi-static mooring line models as opposed to physically-realistic dynamic mooring line models was studied through a suite of comparison tests performed on three floating turbine designs using test cases incorporating both steady and stochastic wind and wave conditions. To perform this comparison, a dynamic finite-element mooring line model was coupled to the floating wind turbine simulator FAST. The results of the comparison study indicate the need for higher-fidelity dynamic mooring models for all but the most stable support structure configurations. Industry consensus on an optimal floating wind turbine configuration is inhibited by the complex support structure design problem; it is difficult to parameterize the full range of design options and intuitive tools for navigating the design space are lacking. The notion of an alternative, "hydrodynamics-based'' optimization approach, which would abstract details of the platform geometry and deal instead with hydrodynamic performance coefficients, was proposed as a way to obtain a more extensive and intuitive exploration of the design space. A basis function approach, which represents the design space by linearly combining the hydrodynamic performance coefficients of a diverse set of basis platform geometries, was developed as the most straightforward means to that end. Candidate designs were evaluated in the frequency domain using linearized coefficients for the wind turbine, platform, and mooring system dynamics, with the platform hydrodynamic coefficients calculated according to linear hydrodynamic theory. Results obtained for two mooring systems demonstrate that the approach captures the basic nature of the design space, but further investigation revealed limitations on the physical interpretability of linearly-combined basis platform coefficients. A different approach was then taken for exploring the design space: a genetic algorithm-based optimization framework. Using a nine-variable support structure parameterization, this framework is able to span a greater extent of the design space than previous approaches in the literature. With a frequency-domain dynamics model that includes linearized viscous drag forces on the structure and linearized mooring forces, it provides a good treatment of the important physical considerations while still being computationally efficient. The genetic algorithm optimization approach provides a unique ability to visualize the design space. Application of the framework to a hypothetical scenario demonstrates the framework's effectiveness and identifies multiple local optima in the design space -- some of conventional configurations and others more unusual ... .
Airborne Wind Energy
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Author : Roland Schmehl
language : en
Publisher: Springer
Release Date : 2018-03-31
Airborne Wind Energy written by Roland Schmehl and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-03-31 with Technology & Engineering categories.
This book provides in-depth coverage of the latest research and development activities concerning innovative wind energy technologies intended to replace fossil fuels on an economical basis. A characteristic feature of the various conversion concepts discussed is the use of tethered flying devices to substantially reduce the material consumption per installed unit and to access wind energy at higher altitudes, where the wind is more consistent. The introductory chapter describes the emergence and economic dimension of airborne wind energy. Focusing on “Fundamentals, Modeling & Simulation”, Part I includes six contributions that describe quasi-steady as well as dynamic models and simulations of airborne wind energy systems or individual components. Shifting the spotlight to “Control, Optimization & Flight State Measurement”, Part II combines one chapter on measurement techniques with five chapters on control of kite and ground stations, and two chapters on optimization. Part III on “Concept Design & Analysis” includes three chapters that present and analyze novel harvesting concepts as well as two chapters on system component design. Part IV, which centers on “Implemented Concepts”, presents five chapters on established system concepts and one chapter about a subsystem for automatic launching and landing of kites. In closing, Part V focuses with four chapters on “Technology Deployment” related to market and financing strategies, as well as on regulation and the environment. The book builds on the success of the first volume “Airborne Wind Energy” (Springer, 2013), and offers a self-contained reference guide for researchers, scientists, professionals and students. The respective chapters were contributed by a broad variety of authors: academics, practicing engineers and inventors, all of whom are experts in their respective fields.
Dynamics Modeling Simulation And Analysis Of A Floating Offshore Wind Turbine
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Author : Mohammed Khair Al-Solihat
language : en
Publisher:
Release Date : 2018
Dynamics Modeling Simulation And Analysis Of A Floating Offshore Wind Turbine written by Mohammed Khair Al-Solihat and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
" Floating Offshore Wind Turbines (FOWTs) are a promising technology to harness the abundant offshore wind energy resources in open ocean areas. A FOWT consists of a floating platform, the moorings, and the wind turbine structure (tower + Rotor-Nacelle Assembly (RNA)). The main focus of this thesis is to develop multibody dynamic models that integrate the structural dynamics, and hydrostatic, hydrodynamic, aerodynamic and mooring system loads. Special efforts are also devoted to characterize the mooring and hydrostatic loads as main sources of systems stiffness that shapes the dynamic behavior of the system. Two approaches for modeling the platform/tower dynamics are developed, a rigid multibody model and a coupled rigid-flexible multibody model. Both models treat the platform, nacelle and rotor as six-degrees-of-freedom (6-DOF) rigid bodies. However, modeling the wind turbine tower dynamics differs between these approaches. The rigid model considers the tower as a 6-DOF rigid body while the flexible model represents the tower as a three-dimensional (3D) tapered damped Euler-Bernoulli beam undergoing coupled general rigid body and elastic motions. In both approaches, the wind turbine drivetrain dynamics is also considered to capture the rotor spin response. The equations of motions of both models are derived symbolically using Lagrange's equations. The hydrostatic restoring loads are evaluated through development of a novel nonlinear hydrostatic approach. This approach allows evaluating the exact hydrostatic force and moment and position of the center of buoyancy as function of the platform displacement and finite rotation. New exact expressions for the water plane area restoring moments are developed. The hydrostatic stiffness matrix at an arbitrary position and orientation of the platform is subsequently derived. A quasi-static approach is then developed to determine the cable tensions of the single-segment and multi-segment mooring system configurations proposed to moor the platform to the seabed. The approach uses different governing equations, depending on whether the mooring lines partially rest on the seabed; are suspended; or fully taut. The exact mooring stiffness is subsequently derived and the influence of several mooring system parameters on the mooring system stiffness is investigated. As an alternative to the quasi-static cable model, a lumped mass cable model incorporating the cable-seabed contact effect is developed to integrate the cable dynamics into the FOWT system dynamics. The equations of motion of the mooring line nodes are assembled for the two mooring system configurations under consideration. A new methodology is also presented to calculate the equilibrium profile of the mooring line lying on a seabed as desirable initial conditions for solving the discretized cable equations of motion. Finally, the theoretical models are implemented through a large simulation tool to analyze the dynamic behavior of the spar FOWT system under study. A series of simulations under defined external loads (load cases) are performed to validate the dynamic models. The simulation results are compared with similar results obtained from well-known offshore wind design codes. The simulation results are found to be in very good agreement with the reported results. Numerical experiments are also performed to investigate the influence of the tower flexibility, mooring system configuration, tower twist and cable dynamics on the system dynamic behavior. The results show that the system responses obtained from the rigid body model under-predict the platform yaw response and exhibit less damping than those obtained from the flexible model. It is also found that the mooring system configuration choice does not influence the platform roll and pitch responses or tower elastic deflections." --
Investigation Of A Fast Orcaflex Coupling Module For Integrating Turbine And Mooring Dynamics Of Offshore Floating Wind Turbines Preprint
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Author :
language : en
Publisher:
Release Date : 2011
Investigation Of A Fast Orcaflex Coupling Module For Integrating Turbine And Mooring Dynamics Of Offshore Floating Wind Turbines Preprint written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
To enable offshore floating wind turbine design, the following are required: accurate modeling of the wind turbine structural dynamics, aerodynamics, platform hydrodynamics, a mooring system, and control algorithms. Mooring and anchor design can appreciably affect the dynamic response of offshore wind platforms that are subject to environmental loads. From an engineering perspective, systembehavior and line loads must be studied well to ensure the overall design is fit for the intended purpose. FAST (Fatigue, Aerodynamics, Structures and Turbulence) is a comprehensive simulation tool used for modeling land-based and offshore wind turbines. In the case of a floating turbine, continuous cable theory is used to emulate mooring line dynamics. Higher modeling fidelity can be gainedthrough the use of finite element mooring theory. This can be achieved through the FASTlink coupling module, which couples FAST with OrcaFlex, a commercial simulation tool used for modeling mooring line dynamics. In this application, FAST is responsible for capturing the aerodynamic loads and flexure of the wind turbine and its tower, and OrcaFlex models the mooring line and hydrodynamic effectsbelow the water surface. This paper investigates the accuracy and stability of the FAST/OrcaFlex coupling operation.
Floating Offshore Wind Energy
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Author : Joao Cruz
language : en
Publisher: Springer
Release Date : 2016-08-20
Floating Offshore Wind Energy written by Joao Cruz and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-08-20 with Technology & Engineering categories.
This book provides a state-of-the-art review of floating offshore wind turbines (FOWT). It offers developers a global perspective on floating offshore wind energy conversion technology, documenting the key challenges and practical solutions that this new industry has found to date. Drawing on a wide network of experts, it reviews the conception, early design stages, load & structural analysis and the construction of FOWT. It also presents and discusses data from pioneering projects. Written by experienced professionals from a mix of academia and industry, the content is both practical and visionary. As one of the first titles dedicated to FOWT, it is a must-have for anyone interested in offshore renewable energy conversion technologies.
Wind Turbines And Aerodynamics Energy Harvesters
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Author : Dan Zhao
language : en
Publisher: Academic Press
Release Date : 2019-08-02
Wind Turbines And Aerodynamics Energy Harvesters written by Dan Zhao and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-08-02 with Science categories.
Wind Turbines and Aerodynamics Energy Harvesters not only presents the most research-focused resource on aerodynamic energy harvesters, but also provides a detailed review on aeroacoustics characteristics. The book considers all developing aspects of 3D printed miniature and large-size Savonious wind harvesters, while also introducing and discussing bladeless and aeroelastic harvesters. Following with a review of Off-shore wind turbine aerodynamics modeling and measurements, the book continues the discussion by comparing the numerical codes for floating offshore wind turbines. Each chapter contains a detailed analysis and numerical and experimental case studies that consider recent research design, developments, and their application in practice. Written by an experienced, international team in this cross-disciplinary field, the book is an invaluable reference for wind power engineers, technicians and manufacturers, as well as researchers examining one of the most promising and efficient sources of renewable energy. Offers numerical models and case studies by experienced authors in this field Contains an overview and analysis of the latest research Explores 3D printing technology and the production of wind harvesters for real applications Includes, and uses, ANSYS FLUENT case files
Offshore Wind Energy
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Author : Finn Gunnar Nielsen
language : en
Publisher: Cambridge University Press
Release Date : 2024-02-29
Offshore Wind Energy written by Finn Gunnar Nielsen and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-02-29 with Science categories.
Many countries have plans to expand wind energy to meet CO2 emissions targets. Lack of available land area and the need for good and stable wind conditions have stimulated the development of offshore wind turbines, which allows for the development of larger turbines. The offshore environment, however, involves new challenges related to the design, installation, operation and maintenance of the turbines. Based on a graduate-level course taught by the author, this book focuses on the opportunities and challenges related to offshore wind turbines. It introduces the offshore environment, including wind and wave dynamics, before discussing the aerodynamics of wind turbines, hydrodynamic loading, marine operations, and wind farm layout. Featuring examples that demonstrate practical application of the topics covered and exercises to consolidate student understanding, this is an indispensable reference text for advanced students and researchers of environmental science and engineering and for industry professionals working in the wind energy sector.
Effects Of Second Order Hydrodynamics On A Semisubmersible Floating Offshore Wind Turbine
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Author :
language : en
Publisher:
Release Date : 2014
Effects Of Second Order Hydrodynamics On A Semisubmersible Floating Offshore Wind Turbine written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The objective of this paper is to assess the second-order hydrodynamic effects on a semisubmersible floating offshore wind turbine. Second-order hydrodynamics induce loads and motions at the sum- and difference-frequencies of the incident waves. These effects have often been ignored in offshore wind analysis, under the assumption that they are significantly smaller than first-order effects. The sum- and difference-frequency loads can, however, excite eigenfrequencies of the system, leading to large oscillations that strain the mooring system or vibrations that cause fatigue damage to the structure. Observations of supposed second-order responses in wave-tank tests performed by the DeepCwind consortium at the MARIN offshore basin suggest that these effects might be more important than originally expected. These observations inspired interest in investigating how second-order excitation affects floating offshore wind turbines and whether second-order hydrodynamics should be included in offshore wind simulation tools like FAST in the future. In this work, the effects of second-order hydrodynamics on a floating semisubmersible offshore wind turbine are investigated. Because FAST is currently unable to account for second-order effects, a method to assess these effects was applied in which linearized properties of the floating wind system derived from FAST (including the 6x6 mass and stiffness matrices) are used by WAMIT to solve the first- and second-order hydrodynamics problems in the frequency domain. The method has been applied to the OC4-DeepCwind semisubmersible platform, supporting the NREL 5-MW baseline wind turbine. The loads and response of the system due to the second-order hydrodynamics are analysed and compared to first-order hydrodynamic loads and induced motions in the frequency domain. Further, the second-order loads and induced response data are compared to the loads and motions induced by aerodynamic loading as solved by FAST.
Coupled Dynamic Modeling Of Floating Wind Turbine Systems
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Author :
language : en
Publisher:
Release Date : 2006
Coupled Dynamic Modeling Of Floating Wind Turbine Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offshore wind turbines in water depths of 10-200 m. Methods for the coupled structural, hydrodynamic, and aerodynamic analysis of floating wind turbine systems are presented in the frequency domain. This analysis was conducted by coupling the aerodynamics and structural dynamics code FAST [4] developed at NREL with the wave load and response simulation code WAMIT (Wave Analysis at MIT) [15] developed at MIT. Analysis tools were developed to consider coupled interactions between the wind turbine and the floating system. These include the gyroscopic loads of the wind turbine rotor on the tower and floater, the aerodynamic damping introduced by the wind turbine rotor, the hydrodynamic damping introduced by wave-body interactions, and the hydrodynamic forces caused by wave excitation. Analyses were conducted for two floater concepts coupled with the NREL 5-MW Offshore Baseline wind turbine in water depths of 10-200 m: the MIT/NREL Shallow Drafted Barge (SDB) and the MIT/NREL Tension Leg Platform (TLP). These concepts were chosen to represent two different methods of achieving stability to identify differences in performance and cost of the different stability methods. The static and dynamic analyses of these structures evaluate the systems' responses to wave excitation at a range of frequencies, the systems' natural frequencies, and the standard deviations of the systems' motions in each degree of freedom in various wind and wave environments. This article in various wind and wave environments. This article explores the effects of coupling the wind turbine with the floating platform, the effects of water depth, and the effects of wind speed on the systems' performance. An economic feasibility analysis of the two concepts was also performed. Key cost components included the material and construction costs of the buoy; material and installation costs of the tethers, mooring lines, and anchor technologies; costs of transporting and installing the system at the chosen site; and the cost of mounting the wind turbine to the platform. The two systems were evaluated based on their static and dynamic performance and the total system installed cost. Both systems demonstrated acceptable motions, and have estimated costs of $1.4-$1.8 million, not including the cost of the wind turbine, the power electronics, or the electrical transmission.