CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Neste trabalho, foi desenvolvida um turbina eÃlica de 490 W em conjunto com uma estrutura para testes de desempenho de aerogeradores deste porte. Foi empregado o mÃtodo analÃtico BEM (Blade Element Momentum Theory) para desenvolvimento, imensionamento, fabricaÃÃo e testes dos componentes da turbina e do sistema de mediÃÃo, abrangendo o estudo aerodinÃmico das pÃs a serem testadas, seu respectivo carregamento, ensaio destrutivo e previsÃo de desempenho. Para tanto, foram consideradas as etapas do cÃlculo e projeto mecÃnico de todos os principais componentes. TambÃm foi definida a metodologia de testes envolvendo a especificaÃÃo de instrumentos, teste em bancada, testes de campo, tratamento de dados e geraÃÃo de resultados. Os resultados foram posteriormente comparados com aqueles gerados pelo BEM. O aparato construÃdo permitiu estabelecer uma estrutura adequada para futuros testes com rotores eÃlicos de maiores diÃmetros e complexidade tecnolÃgica. / In this paper was developed a small scale wind turbine and a structure for performance testing. It was employed the BEM (Blade Element Momentum Theory) to developing, design, fabrication and tests of wind turbine and the measuring system, including the blades aerodynamic analysis which was tested, it respective loading, destructive test and performance forecast. It was considered the complete mechanical design of main components. It was defined the tests methodology involving the instruments specifications, bench tests, field experiments, collected data analysis and results exposition and discussion. In order to validate the manufactured structure and system, it was verified the aerodynamic performance of a small scale wind turbine with 490 W. The results were compared with those proposed by BEM theory. The constructed device allowed establishing an appropriate condition for bigger wind turbine rotor in the future and with more technological complexity.

Floating wind technology has the potential to produce low-carbon electricity on a large scale: it allows the expansion of o shore wind harvesting to deep water, indicatively from 50-60 to a few hundred metres depth, where most of the worldwide technical resource is found. New design specifi cations are being developed for floating wind in order to meet diverse criteria such as conversion effi ciency, maintainability, buoyancy stability, and structural reliability. The last is the focus of this work. The mechanics of floating wind turbines in wind and waves are investigated with an array of numerical means. They demand the simulation of multiple processes such as aerodynamics, hydrodynamics, rotor and structural dynamics; understanding their interaction is essential for engineering design, verifi cation, and concept evaluation. The project is organised in three main parts, presented below. Aero-hydro-mechanical simulation, characterising the rigid-body motions of a floating wind turbine. An investigation of multi-physical couplings is carried out, mainly through EDF R&D's time-domain simulator CALHYPSO. Wave forces are represented with the potential- ow panel method and the Morison equation. Aerodynamic forces are represented by a thrust model or with the blade element momentum theory. Main fi ndings: Exposure of fi nite-angle coupling for semi-submersible turbines with focus on heave plate excursion; characterisation of the aerodynamic damping of pitch motion provided by an operating vertical-axis turbine. Dynamic mooring simulation, focussed on highly compliant mooring systems, where the fluid-structure interaction and mechanical inertial forces can govern line tension. EDF R&D's general-purpose, finite-element solver Code Aster is confi gured for this use exploiting its nonlinear large-displacement and contact mechanics functionalities. Main findings: Demonstration of a Code Aster-based work ow for the analysis of catenary mooring systems; explanation of the dynamic mooring eff ects previously observed in the DeepCwind basin test campaign. Aeroelastic analysis of vertical-axis rotors, aimed at verifying novel large-scale floating wind turbine concepts in operation, when aeroelastic-rotordynamic instabilities may occur. The finite-element modal approach is used to qualify rotor vibrations and to estimate the associated damping, based on the spinning beam formulation and a linearised aerodynamic operator. Main fi ndings: Characterisation of the vibration modes of two novel vertical-axis rotor concepts using the Campbell diagram; estimation of the related aerodynamic damping, providing information on the aeroelastic stability of these designs.

Climate Change and Energy Security have been dominating the global energy agenda. In response the United Kingdom (UK) set a target of reducing emissions by 80% by 2050, and have accepted the European Directive to produce 15% of energy by renewable resources by 2020. Despite doubts in the last few years, the UK are on track to not only meet but exceed the target placed upon them, which sets them in good light for the long term 2050 emission reduction. This research investigated the barriers in the industry such as the planning process delays and public perception. Findings suggested that negative public perceptions still remain, with onshore projects gaining more attention than offshore projects. The planning system whilst showing an improvement in overall decision time still showed signs of delays in the pre-examination process. The research also highlighted signs of a predicted development plateau in onshore schemes, with approved capacity rates slowing in the year 2014. Furthermore, the political structure surrounding wind energy has become fragile, following recent comments from the Conservative party, suggesting they will see an end to onshore wind should they gain election in 2015. Therefore despite positive steps taken by the UK towards renewable energy targets, the future of wind energy is not certain.

Orientador: Milton Dias Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T23:46:51Z (GMT). No. of bitstreams: 1 Silva_GustavoRobertodeSouza_M.pdf: 19462532 bytes, checksum: 9591493a03edfc2b4ed7c18c9cf7005a (MD5) Previous issue date: 2015 / Resumo: Entre os anos de 2004 e 2014 a capacidade total instalada de aerogeradores no mundo apresentou um crescimento de aproximadamente 700%. Este crescimento tão acentuado tem ocorrido devido à atual preocupação mundial com o desgaste do planeta e a consequente busca por novas fontes de energia renováveis e limpas. Evidentemente, esta situação tem atraído muitos investimentos para o estudo de geradores eólicos mas o que se observa na prática é que um número significativo de falhas prematuras ainda ocorrem nos componentes dos aerogeradores. Problemas com a caixa de engrenamento estão entre as principais causas de downtime de um aerogerador. Estudos ainda mais profundos relacionados a este assunto são necessários para o desenvolvimento de projetos de turbinas eólicas mais confiáveis. O presente trabalho se insere neste contexto analisando o comportamento vibratório torcional do trem de potência de um aerogerador de eixo horizontal de velocidade variável. Para tanto, utiliza-se um modelo de múltiplos corpos no qual são incorporados os efeitos da rigidez variável dos engrenamentos helicoidais, fazendo com que o sistema resultante seja linear e variante com o tempo. Os parâmetros modais - frequências naturais, fatores de amortecimento e modos de vibrar - do sistema linear e invariante no tempo equivalente são apresentados. Foram também realizadas simulações com o aerogerador operando nas condições de velocidades de rotação constante e variável, sempre funcionando em faixas de operação compatíveis com o gerador eólico estudado. Os resultados das simulações foram analisados utilizando ferramentas de processamento de sinais estacionários e não estacionários. Estes resultados mostram a presença de forças dinâmicas internas à caixa de engrenagens que contém componentes de frequência iguais às frequências do engrenamento e suas múltiplas. Demonstra-se que estas forças, dependendo da velocidade de operação da máquina e das características do par engrenado, podem excitar as frequências naturais do sistema, e isto, por sua vez, pode levar ao desgaste prematuro dos componentes do aerogerador. Verifica-se também a ocorrência de ressonâncias de segunda ordem, característica de sistemas variantes com o tempo / Abstract: Between 2004 and 2014, the total capacity installed of wind turbines in the world presented an increase of approximately 700%. This very sharp increase has been due to the current global concerns about the planet wear and the consequent search for new sources of renewable and clean energy. Clearly, this situation has attracted many investments for the wind turbines study, but in practice it is observed that a significant number of premature failures still occur in the wind turbine components. Problems with the gear box are one of the leading causes of the downtime of a wind turbine. Deeper studies related to this matter are necessary for the development of more trustable wind turbines projects. The main work was inserted in this context analyzing the torsional vibration behavior of the power train of a horizontal axis wind turbine with variable speed. To do so, a multibody model was used in which the variable stiffness effects of the helical gear ratio were embedded, so that the resulting system was linear time-varying. The modal parameters ¿ natural frequencies, damping factors and vibration modes- of the equivalent linear time-invariant system were presented. Simulations with a wind turbine operating in constant and variable rotation speed conditions were also made, always working on compatible operating ranges with the wind generator studied. The simulations results were analyzed using stationary and not stationary signal processing tools. These results showed the presence of dynamic forces inside the gear box containing the frequencies components equal to the gear meshing frequencies and its multiples. Depending of the operation machine speed and the gear pair characteristics, it was demonstrated that these forces may excite the natural frequencies of the system, and in turn, this can lead to premature wear of the wind turbine components. It is also verified the occurrence of second-order resonances and linear time-varying systems characteristics / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

The simulation of the turbulent and potentially separating flow around a rotating, twisted, and tapered airfoil is a challenging task for CFD simulations. This thesis describes CFD simulations of the NREL Phase VI turbine that was experimentally characterized in the 24.4m X 36.6m NREL/NASA Ames wind tunnel. All computations in this research are performed on the experimental base configuration of 0o yaw angle, 3o tip pitch angle, and a rotation rate of 72 rpm. The significance of specific mesh resolution regions to the accuracy of the CFD prediction is discussed. The ability of CFD to capture bulk quantities, such as the low speed shaft torque, and the detailed flow characteristics, such as the surface pressure distributions, are explored for different inlet wind speeds. Finally, the significant three-dimensionality of the boundary layer flow is demonstrated.

No description available.

A literature review of current design and analysis methods for offshore wind turbine (OWT) foundations is presented, focusing primarily on the monopile foundation. Laterally loaded monopile foundations are typically designed using the American Petroleum Institute (API) p-y method for offshore oil platforms, which presents several issues when extended to OWTs, mostly with respect to the large pile diameters required and the effect of cyclic loading from wind and waves. Although remedies have been proposed, none have been incorporated into current design standards. Foundations must be uniquely designed for each wind farm due to extreme dependence on site characteristics. The uncertainty in soil conditions as well as wind and wave loading is currently treated with a deterministic design procedure, though standards leave the door open for engineers to use a probability-based approach. This thesis uses probabilistic methods to examine the reliability of OWT pile foundations. A static two-dimensional analysis in MATLAB includes the nonlinearity of p-y soil spring stiffness, variation in soil properties, sensitivity to pile design parameters and loading conditions. Results are concluded with a natural frequency analysis.

No description available.

No description available.

The United Nations have declared the effects of climate change as the “defining issue of our time” (United Nations, 2019). As a result of increased industrialization in the last century to keep up with the demands of a growing global population, the global output of greenhouse emissions has rocketed, which is linked to the shifting and abnormal weather patterns of the planet. Electricity and heat production alone are attributed to generating 25% of greenhouse gas emissions (Edenhofer, et al.). To alleviate the increasing levels of carbon emission there is an effort to transition in green energy power generation sources like wind energy that is abundantly available in the midwestern United States. This study aims to implement the Blade Element Method derived modeling methods for predicting the performance of a wind turbine. The experimental results obtained from the MEXICO project is employed as the validation source for the research.