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Análise numérica e experimental de perfis aerodinâmicos para aprimoramento do projeto de turbinas H-Darrieus; Airfoil numerical and experimental analisys for h-darrieus wind turbine optimization

Reis, Guilherme Leo Rossi
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
POR
Relevância na Pesquisa
97.39%
Este trabalho consiste na análise da influência de uma cavidade na parte inferior de um perfil aerodinâmico utilizado em turbinas eólicas H-Darrieus. A análise é feita utilizando a dinâmica dos fluídos computacional e testes experimentais. Utiliza-se o software comercial ANSYS – Fluent 14.0 para a solução das equações da conservação de massa e de Navier-Stokes com média de Reynolds. Os modelos de turbulência Spalart-Allmars, k-epsilon, k-ω e k-ω SST são utilizados e comparam-se alternativas de discretização espacial com a finalidade de avaliar a influência nos valores obtidos com uma velocidade prescrita na entrada do domínio de 10m/s. Pelas forças originadas pelo atrito viscoso e pelos gradientes de pressão nas pás, obtêm-se o coeficiente de torque e de potência em cada uma das simulações. Através da integração das pressões e das forças de arrasto sobre os perfis testados em túnel aerodinâmico, levantam-se as curvas dos coeficientes de sustentação e arrasto de cada perfil, respectivamente, através das quais é possível obter o torque gerado pela turbina. Os resultados encontrados são bastante representativos para o fenômeno estudado, uma vez que as velocidades prescritas são da ordem de operação desse tipo de turbina. Mostra-se que o perfil com cavidade apresenta um melhor desempenho em relação ao perfil original para uso em turbinas H-Darrieus.; This work consist on the analysis of the influence of a cavity on the lower surface of an airfoil used in H-Darrieus Wind Turbine. The analysis is performed using Computational Fluid Dynamics and experimental tests. The commercial software ANSYS – Fluent 14.0 is used in order to solve the continuity and Reynolds-Averaged Navier-Stokes equations. Spalart-Allmars...

Avaliação do desempenho de um aeromotor de eixo vertical

Geroto, Gustavo Henrique Rossetti
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 104 p. : il.
POR
Relevância na Pesquisa
26.9%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Engenharia Mecânica - FEG; Esta dissertação apresenta o desenvolvimento, construção e avaliação de desempenho de um aeromotor de eixo vertical. Os ventos no local de instalação tiveram sua velocidade variando entre 1,4 m/s a 7 m/s. O modelo do aeromotor construído foi o Darrieus com três pás de perfil aerodinâmico constante. O rotor possui 3 m de diâmetro e a torre 6 m de altura. O perfil utilizado na construção das pás foi o NACA 0018-53, com bordo de ataque modificado. Este perfil apresenta o coeficiente de sustentação maior que o perfil padrão sem apresentar aumento significativo no coeficiente de arrasto. Foi adicionado um slot na parte traseira das pás visando baixar a velocidade de partida. A velocidade de partida média observada foi de 1,7 m/s. Com vento de 7 m/s o aeromotor desenvolveu 63 rpm no eixo. A potência máxima registrada foi de 82 W a 35 rpm sob a incidência de um vento de 4,6 m/s. Nesta condição, o coeficiente de potência máximo alcançado foi de 0,31 e a velocidade de ponta de pá (TSR) foi de 1,2. O equipamento se mostrou adequado ao local de instalação mesmo desenvolvendo baixos valores de potência final; This dissertation presents a vertical axis wind turbine development...

Darrieus wind turbine performance prediction: computational modeling

Melício, Rui; Mendes, Victor; Figueiredo, João; Reis, Heitor
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Parte de Livro
ENG
Relevância na Pesquisa
66.89%
The Vertical Axis Wind Turbines Darrieus is facing a rapid installations growth due to the interest for a decentralizing generation. The Darrieus aerodynamic behavior analysis is a hard computational task. This paper starts by offering an insight into the Darrieus wind turbines performance prediction and proposes an algorithm based on the Multiple Streamtube modeling as a prediction approach in order to have an admissible handing in an Internet of things environment.

Novo aerogerador de eixo vertical integrado numa rede inteligente em contexto urbano

Batista, Nelson António Martins da Costa
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Tese de Doutorado
POR
Relevância na Pesquisa
47.16%
Esta tese incide sobre o desenvolvimento de um novo aerogerador de eixo vertical do tipo Darrieus integrado numa rede inteligente em contexto urbano e a implementação de um protótipo do aerogerador para a conversão de energia eólica em energia elétrica. É estudado o auto arranque do aerogerador, sendo apresentada uma metodologia para o desenvolvimento de perfis aerodinâmicos da pá. É apresentado o novo perfil aerodinâmico EN0005 permitindo auto arranque do aerogerador sem componentes extra. Uma nova metodologia de modelação de aerogeradores Darrieus no que respeita às formas de pás é apresentada. Testes de campo recorrendo à utilização de redes de dados aplicando a norma ZigBee são apresentados, permitindo organizar uma proposta de uma arquitetura de rede elétrica inteligente e de segurança de dados. Testes em ambiente urbano e em ambiente controlado de túnel de vento são apresentados no sentido de avaliar as caraterísticas do protótipo do aerogerador, sendo apresentado sensores adequados à avaliação das caraterísticas do aerogerador; NEW VERTICAL AXIS WIND TURBINE INTEGRATED IN A SMART GRID IN URBAN CONTEXT ### Abstract: This thesis focuses on the development of a new Darrieus type vertical axis wind turbine integrated in a smart grid in urban context and the implementation of a prototype for the conversion of wind energy in electric energy. The self-start of the aero-generator prototype is studied...

Variable pitch darrieus water turbines

Kirke, Brian; Lazauskas, Leo Victor
Fonte: The Japan Society of Mechanical Engineers Publicador: The Japan Society of Mechanical Engineers
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
47.02%
In recent years the Darrieus wind turbine concept has been adapted for use in water, either as a hydrokinetic turbine converting the kinetic energy of a moving fluid in open flow like an underwater wind turbine, or in a low head or ducted arrangement where flow is confined, streamtube expansion is controlled and efficiency is not subject to the Betz limit. Conventional fixed pitch Darrieus turbines suffer from two drawbacks, (i) low starting torque and (ii) shaking due to cyclical variations in blade angle of attack. Ventilation and cavitation can also cause problems in water turbines when blade velocities are high. Shaking can be largely overcome by the use of helical blades, but these do not produce large starting torque. Variable pitch can produce high starting torque and high efficiency, and by suitable choice of pitch regime, shaking can be minimized but not entirely eliminated. Ventilation can be prevented by avoiding operation close to a free surface, and cavitation can be prevented by limiting blade velocities. This paper summarizes recent developments in Darrieus water turbines, some problems and some possible solutions.; Kirke Brian amd Lazauskas Leo; Copyright © 2008 National Institute of Informatics. All Rights Reserved

VAWT with controlled blades : influence of wake of one turbine on power coefficient on the next turbine

BAYEUL-LAINE, Annie-Claude; SIMONET, Sophie; BOIS, Gérard
Fonte: IC-EpsMsO Publicador: IC-EpsMsO
EN
Relevância na Pesquisa
56.9%
Power production from wind turbines is affected by several conditions like wind speed, turbine speed, turbine design, turbulence, changes of wind direct ion, wake of previous turbines. These conditions are not always optimal and have negative effects on most turbines. The present wind turbine is a small one which allows to be used on roofs or in gardens to light small areas like publicity boards, parkings, roads or for water pumping, heating... This turbine is less affected by these conditions because the blades combine a rotating movement around each own axis and around the main turbine’ s one. Due to this combination of movements, flow around this turbine is more optimized than classical Darrieus turbines. It has been shown in previous studies that the best configuration was obtained with straight blades, a blade stager angle comprised between 0 and 8 degrees and a range of non-dimensional velocity from 0.4 to 0.6 for a very good power coefficient of about 0.4 in case of one VAWT. The present study points up the influence of the position of each VAWT in a group of three turbines and of the distances between turbines. It deals on global and local performances of these turbines.

Simulating variable pitch crossflow water turbines: A coupled unsteady ONERA-EDLIN model and streamtube model

PAILLARD, B.; HAUVILLE, Frédéric; ASTOLFI, Jacques Andre
Fonte: ELSEVIER Publicador: ELSEVIER
EN
Relevância na Pesquisa
27.15%
This article describes a new method for simulating unsteady hydrodynamics forces and moments on the blades of a crossflow ‘Darrieus’ turbine with active pitch variation. This method is based on the ONERAEDLIN dynamic stall model, coupled with a momentum streamtube model to take into account the turbine interference on the flow. Both models are presented, and compared separately with experimental results for a pitching airfoil for the ONERA-EDLIN model; and for Darrieus turbine for the momentum theory. The model coupling is then detailed and compared with experimental data taken from the open literature [1] The turbine has 2 straight blades with a NACA 0012 section operating in water at a mean chord Reynolds number of 4 104 for tip speed ratio l ¼ 2.5, 5 and 7.5. Good agreement was found for average l ¼ 5, and qualitative agreement could be obtained at low and high l, where dynamic stall effects and interference effects respectively are predominant. This is positive because l ¼ 5 is the closest value from the optimal power production point. Variable pitch is finally introduced in the model and several functions are tested in order to increase efficiency. A maximum increase of 53% on the power coefficient was found to occur with a sinusoidal law. 2012 Elsevier Ltd. All rights reserved. 1. Introduction Tidal turbines are currently the power source that shows the most advantages [2]. No land occupation like a dam...

Numerical study of flow stream in a mini VAWT with relative rotating blades

BAYEUL-LAINE, Annie-Claude; SIMONET, Sophie; DOCKTER, Aurore; BOIS, Gérard
Fonte: Arts et Métiers ParisTech Publicador: Arts et Métiers ParisTech
EN
Relevância na Pesquisa
26.83%
Today, wind energy is mainly used to generate electricity and more and more with a renewable energy source character. Power production from wind turbines is affected by several conditions like wind speed, turbine speed, turbine design, turbulence and changes of wind direction. These conditions are not always optimal and have negative effects on most turbines. The present turbine is supposed to be less affected by these conditions because the blades combine a rotating movement around each own axis and around the main turbine’s one. Due to this combination of movements, flow around this turbine can be more optimized than classical Darrieus turbines. The turbine has a rotor with three straight blades of symmetrical aerofoil. Paper presents unsteady simulations that have been performed for one wind velocity and different blades stagger angles. The influence of two different blades geometry is studied for four different constant rotational speeds.

On a self-start Darrieus wind turbine: blade design and field tests

Melicio, Rui
Fonte: Renewable and Sustainable Energy Reviews (ELSEVIER) Publicador: Renewable and Sustainable Energy Reviews (ELSEVIER)
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
76.87%
This paper is about a design of an urban area Darrieus VAWT, having self-start ability due to an innovative profile design named EN0005, avoiding the need of extra components or external electricity feed-in. An approach is presented to study the ability of a blade profile to offer self-start ability. Methodologies applied for the blade body and for profile development are reported. Field tests and main conclusions are presented to persuade for the arrangement of this design.

Innovative design on technology of urban Darrieus VAWT: field tests

Melicio, Rui
Fonte: 16th IEEE International Conference on Computer as a Tool — EUROCON 2015 Publicador: 16th IEEE International Conference on Computer as a Tool — EUROCON 2015
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.99%
This paper is about an innovative design for an urban Darrieus Vertical Axis Wind Turbine (VAWT), having the ability of having self-start at low wind velocities, but without the need for extra components or external electricity feed-in. A new mathematical model to assess complex shaped Darrieus VAWT prototype is presented in this paper and offers a new approach to the Double Multiple Streamtube model. Field tests to assess the behavior of the prototype and main conclusions are presented.

FLOW PHYSICS OF 3-BLADED STRAIGHT CHORD H-DARRIEUS WIND TURBINE

Gupta, Rajat; Biswas, Agnimitra
Fonte: JUEE Press Publicador: JUEE Press
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 17/08/2013 ENG
Relevância na Pesquisa
87.15%
Steady-state two-dimensional Computational Fluid Dynamics (CFD) simulations were performed using Fluent 6.0 software to analyze the flow physics of 3-bladed straight chord H-Darrieus wind turbine having blade twist of 300 for 10% of its chord at the trailing ends. The flow was simulated using finite volume method coupled with moving mesh technique to solve mass and momentum conservation equations. The standard k-ε turbulence model with enhanced wall condition was used. Second-order upwind discretization scheme was adopted for pressure-velocity coupling of the flow. Flow physics of the turbine was analyzed with the help of pressure and velocity contours. It was found that velocity magnitude decreases from upstream to downstream side across the turbine, which will cause overall lift for the turbine. Further, blade twist at the trailing ends creates circulations that interact with the blades in a direction opposite to the direction of rotation of the turbine which would enhance power production for the three bladed turbine.