Dissertations / Theses on the topic 'Savonius rotor'

The diploma thesis is focused on designer works of Savounius rotor for Raječko location. Finish of this design work is equipment, which will be used in this location as decentralized source of electrical energy. In thesis are written manufacturing processes as so as the process of design part including the calculation part, which is focused on characteristic quantity of Savonius rotor. Thesis is finished by econominal assessment of project.

Mestrado em Engenharia Mecânica<br>A energia eólica é atualmente uma fonte de energia renovável utilizada pelo homem através de diferentes mecanismos. O rotor de Savonius, uma turbina de eixo vertical, é uma opção para produção de energia em pequena escala. A produção e venda de energia elétrica à rede pública, fruto de fontes renováveis, é hoje em dia uma opção enquadrada na nossa legislação. Com base no potencial das características dos rotores de Savonius analisou-se experimentalmente quatro configurações diferentes com o intuito de comparar as suas performances, sendo que a configuração de centro aberto e pás fechadas obteve os melhores resultados ao nível de produção de energia eólica.<br>Wind energy is currently a renewable energy source used by man through different mechanisms. The Savonius rotor, a vertical-axis turbine, is an option for small-scale power production. The production and sale of electricity to the public grid, by renewable sources, is nowadays an option framed in our legislation. Based on the potential of the characteristics of the Savonius rotors, four different configurations were experimentally analyzed in order to compare their performances, being that open-center and closed-bladed configuration obtaining the best results of wind energy production.

The aim of this Master Thesis is to study numerically the aerodynamic performance of two small examples of horizontal axis domestic wind turbines: a conventional Savonius rotor, designed and built by a group of students of the Polytech of Tours (France), and its optimization, a helical Savonius rotor. In the first research project, the exploration is conducted even experimentally, testing the turbine in a wind tunnel present in the Polytech. The numerical investigation is carried out by the use of a software based on Computational Fluid Dynamics named Star CCM+, which helps studying the main fluid dynamics aspects as flow velocity, pressure and coefficients of performance. The second project consists in a helical Savonius rotor: according to the literature, the helical shape, comparing with the conventional Savonius rotor, usually shows better performances. After the 3D design on Catia, the turbine was printed using the 3D printer, on a reduced scale. CFD simulations allow to study the fluid dynamic features. Afterwards, thanks to a comparison between the two Savonius models, the performance enhancement of the new one is shown, together with a practical understanding gained of the parameters influencing aerodynamics the most. By means of the simulations, the helical rotor presents a power coefficient of 10%, which is better than the one of the conventional rotor, found at 7% for the same Tip Speed Ratio. Consequently, even the power produced by the new turbine, resulted to be better than the conventional windmill.

Important stages in the development of a wind energy operated irrigation system, which is simple in design and easy to maintain, are described from model tests in wind tunnels through to a prototype prepared for field tests. The attention is focussed on gross features of the protoype including the blade geometry and aspect ratio; mast, sleeve and bearing assemblies; braking system and a load matching concept. Described towards the end are the field test arrangements of the prototype and associated instrumentation. Even according to the most conservative estimate, the prototype tests suggest that the windmill should be able to deliver around 3000 liters of water per day (eight hours of wind) to a head of 5 m in a 24 km/h wind.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate

Using of wind energy belongs to one of the fastest developing segments in the power production from renewable resources, which also relates to new studies and development of different types of power stations and brings new ideas to small wind sources spheres too. Savonius rotor is included in these spheres as well. This thesis deals with a complete design, realization and trial measurement of single-step Savonius rotor model. Introduction part treats of basic division and rotor utilization. Design part includes the design as well rotor graphical documentation. In the following part there is data evaluation, which leads to comparison with theoretical calculations. The final part includes an examination of possible utilization of Savonius rotor for generation of electricity.

This master‘s thesis deals with the simulation of small wind power plant with Savonius-Darrieus rotor. On the base of the actuator disk theory the performance of modeled power plant is predicted in theoretical part and the power coefficient as well. The process of designing the wind model is also described in this theoretical part. The practical part of this thesis is dedicated to the creating a model of DS300 vertical axis hybrid wind turbine in Matlab/Simulink. This model was used to generating of the power curve of modeled wind power plant and for the computing of power and total produced energy during an average and above-average day as well. The whole thesis is enclosed by evaluating of obtained results.

Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica<br>O objectivo do presente trabalho, passa por encontrar soluções para a reutilização de componentes em fim-de-vida, usando-os exactamente como se encontram, desempenhando as mesmas funções para que foram projectados, fazendo apenas pequenas adaptações para se adequarem à nova utilização. Para a reutilizar estes componentes a solução escolhida, foi projectar uma turbina eólica, recorrendo a componentes de automóvel. Sendo o vento um recurso natural disponível em grande parte do globo terrestre, torna aliciante a possibilidade de diminuir a pegada ambiental dos componentes, reutilizando-os, bem como produzir energia recorrendo à energia eólica. A turbina escolhida foi a de savonius, pois tem custos de fabrico reduzidos, pela simplicidade de construção e montagem bem como ser uma turbina interessante para pequenos aproveitamentos energéticos. Foi estudado o rotor de savonius para compreender os esforços a que se encontra sujeito devido à acção do vento, para posteriormente projectar a estrutura do rotor e de suporte da turbina. Durante o presente trabalho foi tido em conta, que se trata de um projecto no âmbito universitário, de modo que a turbina terá que ser polivalente para possibilitar outros estudos no futuro.

Este trabalho apresenta a simulação numérica do escoamento turbulento em torno de uma turbina eólica de eixo vertical de pequeno porte, Savonius tipo helicoidal com torção de 180° nas pás. Com o intuito de avaliar a metodologia computacional empregada os resultados numéricos obtidos são comparados com os resultados experimental e numérico contidos no estado da arte. Também, compara-se o coeficiente de toque da turbina Savonius helicoidal com a turbina Savonius convencional. As simulações numéricas são baseadas no Método de Volumes Finitos, e para tal emprega-se o programa Fluent /Ansys versão 13.0 que resolve as equações da continuidade e as equações de Navier-Stokes com médias de Reynolds, juntamente com o modelo de turbulência . As simulações são desenvolvidas empregando diferentes malhas computacionais em estudos transientes, tridimensionais, com a turbina estacionária. A avaliação da qualidade da malha é realizada através do método de Índice de Convergência de Malha (GCI) o qual analisa o quão longe os resultados estão da solução assintótica para a malha utilizada. Após a análise da qualidade de malha, realizam-se simulações com a turbina em rotação as quais fazem uso da malha contendo uma região móvel possibilitando a imposição de uma velocidade angular ao rotor. O coeficiente de torque é obtido nas simulações e a partir dele calcula-se o coeficiente de potência. Além da análise do desempenho do rotor realiza-se uma análise qualitativa das características do escoamento sobre a turbina. A turbina Savonius helicoidal apresenta um valor de coeficiente de potência de 0,175 para a razão de velocidade de ponta de 0,58 considerando correção do efeito de bloqueio. Os resultados obtidos apresentam boa concordância com os resultados publicados por outros autores.<br>This dissertation presents the numerical simulation of the turbulent flow around of a small sized vertical axis wind turbine, consisting in a helical Savonius type with a 180° degree of blade twist. In order to evaluate the used methodology the obtained results are compared with the state of the art numerical and experimental data. It will be also presented the comparison between the torque coefficient of the conventional Savonius turbine and the helical Savonius turbine. The numerical simulations are based on the Finite Volume Method (FVM), using the commercial code Fluent/ANSYS version 13.0, which solves the continuity and Navier-Stokes through the Reynolds time-averaged methodology, including the turbulence model. The simulations are developed using different computational meshes for transient and three-dimensional studies with the stationary turbine. The evaluating the quality of the mesh is performed by of Grid Convergence Index (GCI) method which analyzes how far the results are the asymptotic solution to the mesh used. After the evaluation of the mesh quality, it was simulated a case considering the rotor motion using the moving mesh configuration, allowing the imposition of an angular velocity to the turbine. In the post-processing stage, it is possible to obtain the torque coefficient on the rotor shaft, allowing the calculation of the power coefficient for the turbine. In addition to the performance analysis, it is also made a qualitative analysis of the flow characteristics over the turbine rotor and in both cases presenting a good correspondence with the results in the literature. The helical Savonius turbine presents a value of power coefficient of 0.175 to a tip speed ratio of 0.58 whereas blocking effect correction.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Includes bibliographical references (p. 26).<br>The D-lab Honduras team designed and constructed a wind-powered water pump in rural Honduras during IAP 2007. Currently, the system does not work under its own power and water must be pumped by hand. This thesis seeks to explore a variety of mechanism and aerodynamic changes to allow the system to function as designed. The novel modifications to the Savonius rotor that were made do not seem to improve its performance. Within the constraints of the installed components, the current rotor should perform well pending other changes. The most promising improvements to the system are weight reducing and friction reducing measures, and in combination with understanding the wind conditions in the immediate vicinity of the rotor, changes will be made this summer so that unassisted wind pumping will be possible.<br>by Aron Zingman.<br>S.B.

Neste trabalho, são inicialmente discutidas as dificuldades referentes à obtenção de resultados numéricos para a operação de uma turbina Savonius independentes do grau de discretização, tamanho de domínio de cálculo e de máximo tempo físico simulado. Também são relatadas as divergências entre as metodologias numéricas e experimentais adotadas por diversos autores, que dificultam análises e comparações dos resultados obtidos por meio dessas metodologias com os resultados próprios obtidos. Devido a esses fatos, no presente trabalho, uma série de procedimentos experimentais e numéricos são realizados para efetuar análises do escoamento sobre uma turbina eólica Savonius. Nos experimentos em canal aerodinâmico, perfis de velocidade e parâmetros da turbulência são obtidos pela técnica de anemometria de fio quente. Medições com o uso de tubos de Pitot e manômetros eletrônicos são efetuadas para avaliar a variação da pressão e os perfis de velocidade média em posições selecionadas. Além de dados para análise, informações úteis para uso como condições de contorno nas simulações numéricas também são obtidas. Os fenômenos são reproduzidos através de simulações numéricas pelo Método de Volumes Finitos, que solucionam as equações da continuidade, de Navier-Stokes com médias de Reynolds e do modelo de turbulência k-ω SST. Análises experimentais e numéricas considerando o escoamento sobre um cilindro, que mantém semelhanças com o escoamento sobre o rotor, também são realizadas. Simulações numéricas do escoamento sobre o cilindro são efetuadas, fornecendo resultados representativos do escoamento real, quando geometrias tridimensionais são aplicadas na modelagem numérica. Nas simulações do escoamento sobre o rotor Savonius em condição estática, resultados representativos do escoamento real são obtidos com o uso de uma modelagem que leva em consideração a rugosidade das pás do rotor, estacionado na posição angular de 90°. Para posições angulares menores, não se obteve uma boa concordância entre os resultados experimentais e numéricos. A realização deste trabalho fornece informações úteis para a análise do fenômeno e tem potencial para contribuir com futuros trabalhos desse tema.<br>This research work initially presents a discussion about the difficulties related to obtaining numerical results for the operation of a turbine Savonius independent of the degree of discretization, calculation domain size and maximum physical time of the simulation. The differences between the numerical and experimental methodologies adopted by various authors difficult the analysis and comparisons of the results obtained through these methods with the results obtained by the methodology. Due to these facts, in this research work, a series of experimental and numerical procedures are performed to conduct analyzes of flow over a Savonius wind turbine. In the experiments on aerodynamic channel, velocity and turbulence profiles parameters are obtained by the technique of hot wire anemometry. Measurements using Pitot tubes and electronic manometers are made to evaluate the variation of pressure and mean velocity profiles at selected positions. In addition to data analysis, useful information for use as boundary conditions in the numerical simulations are also obtained. The phenomena are reproduced through numerical simulations by Finite Volume Method, that solve the equations of continuity, Reynolds-averaged Navier–Stokes equations and the equation of the turbulence model k-ω SST. Experimental and numerical analyzes considering the flow over a cylinder, which holds similarities with the flow over the rotor, are also performed. Numerical simulations of the flow over the cylinder are made, providing results representative of the actual flow when three-dimensional geometries are applied in numerical modeling. In flow simulations over the Savonius rotor in static condition, at 90°, representative results of the actual flow are obtained using a model that takes into account the roughness of the rotor blades. For smaller angular positions a good agreement between experimental and numerical results was not obtained. This work provides useful information for the analysis of the phenomenon and has the potential to contribute to future work on this theme.

There is an urgent need for economical, clean, sustainable energy supplies, not only in densely populated areas where electricity grids are appropriate, but also in rural areas where stand-alone power supply systems are often more suitable. Although electrical power supply is very versatile and convenient, it introduces unnecessary complexity for some off-grid applications where direct mechanical shaft power can conveniently be provided by a wind turbine. Wind energy is one of the more promising renewable energy sources. Most wind turbines are of the horizontal axis type, but vertical axis wind turbines or VAWTs have some advantages for direct mechanical drive applications. They need no tail or yaw mechanism to orient them into the wind and power is easily transmitted via a vertical shaft to a load at ground level. Blades may be of uniform section and untwisted, making them relatively easy to fabricate or extrude, unlike the blades of horizontal axis wind turbines (HAWTs) which should be twisted and tapered for optimum performance. Savonius rotor VAWTs are simple and may have a place where the power requirement is only a few Watts, but they are inefficient and uneconomical for applications with larger power requirements. VAWTs based on the Darrieus rotor principle are potentially more efficient and more economical, but those with fixed pitch blades have hitherto been regarded as unsuitable for stand-alone use due to their lack of starting torque and low speed torque. This starting torque problem can be overcome by using variable pitch blades, but most existing variable pitch VAWTs, variously known as giromills or cycloturbines, need wind direction sensors, microprocessors and servomotors to control the blade pitch, making them impracticable for stand-alone, non-electrical applications. A simpler but less well known concept is passive or self-acting variable pitch in which the blades are free to pitch under the combined action of aerodynamic and inertial forces in such a way that a favourable blade angle of attack is maintained without the complexity of conventional variable pitch systems. Several fonns of self-acting variable pitch VAWTs or SAPVAWTs have been described in the literature, several patents exist for variants on the concept, and at least two companies world-wide have attempted to commercialise their designs. However the aerodynamic behaviour of these devices has been little understood and most designs appear to have been based on nothing more than a qualitative appreciation of the potential advantages of the concept. This thesis assesses the potential of both fixed and passive variable pitch vertical axis wind turbines to provide economical stand-alone power for direct mechanical drive applications. It is shown that the starting torque and low speed torque problems of VAWTs can be overcome either by passive variable pitch or by a combination of suitable blade aerofoil sections, either rigid or flexible, and transmissions which unload the rotor at low speeds so that high starting torque is not necessary. The work done for this thesis is made up of a sequence of stages, each following logically from the previous one: 1. Several tasks have been identified which could be performed effectively by a self-starting vertical axis wind turbine using direct mechanical drive. These include, a. pumping water, b. purifying and/or desalinating water by reverse osmosis, c. heating and cooling using vapour compression heat pumps, d. mixing and aerating water bodies and e. heating water by fluid turbulence. Thus it is apparent that such a system has the potential to make a useful contribution to society. 2. A literature survey of existing VAWT designs has been carried out to assess whether any are suitable for these applications. 3. As no suitable existing design was identified, an improved form of SAPVAWT has been developed and patented. 4. To optimise the performance of the improved SAPVAWT, a mathematical model has been developed in collaboration with Mr Leo Lazauskas of the University of Adelaide (see Kirke and Lazauskas, 1991, Lazauskas and Kirke, 1992). As far as the author of the present thesis is aware, this is the only existing mathematical model able to predict the performance of this particular type of SAPVAWT, and one of only two worldwide which model SAPVAWTs. 5. In order to use the mathematical model to predict the performance of a given SAPVAWT, it is necessary to have lift, drag and moment data for the aerofoil profile to be used, over a wide range of incidence and Reynolds numbers. A literature search has revealed large gaps in the existing data. 6. Wind tunnel testing has been carried out to assess the effect of camber on the performance of one set of NACA sections at low Reynolds number, and performance figures for other sections have been estimated by interpolation from existing data. 7. Using the assembled aerofoil data, both experimental and estimated, the mathematical model has been used to predict the performance of both fixed and variable pitch VAWTs. It has been found to predict correctly the performance of known fixed pitch VAWTs and has then been used to predict the performance of fixed pitch VAWTs with cambered blades using newly developed profiles that exhibit superior characteristics at low Reynolds numbers. Results indicate that fixed pitch VAWTs using these blade sections should self-start reliably. 8. To validate the mathematical model predictions for self-acting variable pitch, a two metre diameter physical model has been built and tested in a wind tunnel, and acceptable agreement has been obtained between predicted and measured performance. 9. To demonstrate the performance of a SAP VA WT under field conditions, a six metre diameter turbine has been designed, fabricated, erected and tested. 10. Because a prime mover such as a wind turbine is of no use unless it drives a toad, particular attention has been paid to the behaviour of complete systems, including the wind turbine, the transmission and the load. It is concluded that VAWTs with the improved self-starting and low speed torque characteristics described in this thesis have considerable potential in stand-alone, direct mechanical drive applications.

There is an urgent need for economical, clean, sustainable energy supplies, not only in densely populated areas where electricity grids are appropriate, but also in rural areas where stand-alone power supply systems are often more suitable. Although electrical power supply is very versatile and convenient, it introduces unnecessary complexity for some off-grid applications where direct mechanical shaft power can conveniently be provided by a wind turbine. Wind energy is one of the more promising renewable energy sources. Most wind turbines are of the horizontal axis type, but vertical axis wind turbines or VAWTs have some advantages for direct mechanical drive applications. They need no tail or yaw mechanism to orient them into the wind and power is easily transmitted via a vertical shaft to a load at ground level. Blades may be of uniform section and untwisted, making them relatively easy to fabricate or extrude, unlike the blades of horizontal axis wind turbines (HAWTs) which should be twisted and tapered for optimum performance. Savonius rotor VAWTs are simple and may have a place where the power requirement is only a few Watts, but they are inefficient and uneconomical for applications with larger power requirements. VAWTs based on the Darrieus rotor principle are potentially more efficient and more economical, but those with fixed pitch blades have hitherto been regarded as unsuitable for stand-alone use due to their lack of starting torque and low speed torque. This starting torque problem can be overcome by using variable pitch blades, but most existing variable pitch VAWTs, variously known as giromills or cycloturbines, need wind direction sensors, microprocessors and servomotors to control the blade pitch, making them impracticable for stand-alone, non-electrical applications. A simpler but less well known concept is passive or self-acting variable pitch in which the blades are free to pitch under the combined action of aerodynamic and inertial forces in such a way that a favourable blade angle of attack is maintained without the complexity of conventional variable pitch systems. Several fonns of self-acting variable pitch VAWTs or SAPVAWTs have been described in the literature, several patents exist for variants on the concept, and at least two companies world-wide have attempted to commercialise their designs. However the aerodynamic behaviour of these devices has been little understood and most designs appear to have been based on nothing more than a qualitative appreciation of the potential advantages of the concept. This thesis assesses the potential of both fixed and passive variable pitch vertical axis wind turbines to provide economical stand-alone power for direct mechanical drive applications. It is shown that the starting torque and low speed torque problems of VAWTs can be overcome either by passive variable pitch or by a combination of suitable blade aerofoil sections, either rigid or flexible, and transmissions which unload the rotor at low speeds so that high starting torque is not necessary. The work done for this thesis is made up of a sequence of stages, each following logically from the previous one: 1. Several tasks have been identified which could be performed effectively by a self-starting vertical axis wind turbine using direct mechanical drive. These include, a. pumping water, b. purifying and/or desalinating water by reverse osmosis, c. heating and cooling using vapour compression heat pumps, d. mixing and aerating water bodies and e. heating water by fluid turbulence. Thus it is apparent that such a system has the potential to make a useful contribution to society. 2. A literature survey of existing VAWT designs has been carried out to assess whether any are suitable for these applications. 3. As no suitable existing design was identified, an improved form of SAPVAWT has been developed and patented. 4. To optimise the performance of the improved SAPVAWT, a mathematical model has been developed in collaboration with Mr Leo Lazauskas of the University of Adelaide (see Kirke and Lazauskas, 1991, Lazauskas and Kirke, 1992). As far as the author of the present thesis is aware, this is the only existing mathematical model able to predict the performance of this particular type of SAPVAWT, and one of only two worldwide which model SAPVAWTs. 5. In order to use the mathematical model to predict the performance of a given SAPVAWT, it is necessary to have lift, drag and moment data for the aerofoil profile to be used, over a wide range of incidence and Reynolds numbers. A literature search has revealed large gaps in the existing data. 6. Wind tunnel testing has been carried out to assess the effect of camber on the performance of one set of NACA sections at low Reynolds number, and performance figures for other sections have been estimated by interpolation from existing data. 7. Using the assembled aerofoil data, both experimental and estimated, the mathematical model has been used to predict the performance of both fixed and variable pitch VAWTs. It has been found to predict correctly the performance of known fixed pitch VAWTs and has then been used to predict the performance of fixed pitch VAWTs with cambered blades using newly developed profiles that exhibit superior characteristics at low Reynolds numbers. Results indicate that fixed pitch VAWTs using these blade sections should self-start reliably. 8. To validate the mathematical model predictions for self-acting variable pitch, a two metre diameter physical model has been built and tested in a wind tunnel, and acceptable agreement has been obtained between predicted and measured performance. 9. To demonstrate the performance of a SAP VA WT under field conditions, a six metre diameter turbine has been designed, fabricated, erected and tested. 10. Because a prime mover such as a wind turbine is of no use unless it drives a toad, particular attention has been paid to the behaviour of complete systems, including the wind turbine, the transmission and the load. It is concluded that VAWTs with the improved self-starting and low speed torque characteristics described in this thesis have considerable potential in stand-alone, direct mechanical drive applications.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Engineering<br>Science, Environment, Engineering and Technology<br>Full Text

A Savonius wind turbine is a self-starting vertical axis rotor. It can be designed to be compact in size and also produces less noise which makes it suitable to integrate into urban spaces such as rooftops and sign-poles. These characteristics make it interesting from a sustainability point of view, especially when aiming to increase the decentralization of electricity production. This thesis aimed to investigate the aerodynamic performance of different two-bladed Savonius profiles by varying the blade arc angle and the overlap ratio. For evaluation, the dimensionless power coefficient and torque coefficient were investigated over different tip speed ratios. The study was conducted numerically with 2D simulations in Ansys Fluent. The partial differential equations describing the characteristics of the flow, including the flow turbulence effects, were solved with the Reynolds-average Navier Stokes in combination with the k-omega SST model. A validation was performed by comparing data from simulated and experimental tests of a semi-circular profile and a Benesh profile. The investigation of the blade arc angle and overlap ratio was performed on a Modified Bach profile. The profile with a blade arc angle of 130 degrees and an overlap ratio of 0.56 generated a maximal power coefficient of 0.267 at a tip speed ratio of 0.9. This blade configuration generated the best performance of all conducted simulations in this project. However, this project contained uncertainties since simulations can never be an exact description of reality. The project was also limited by the computational power available. Nevertheless, according to the conducted simulations, it was observed that a higher blade arc angle and a larger overlap ratio seem to generate higher efficiency.<br>En Savonius vindturbin är en självstartande vertikalaxlad rotor som kan utformas i en kompakt design samtidigt som den producerar mindre oljud än horisontalaxlade vindkraftverk. Dagens hållbarhetssträvan i kombination med Savonius turbinens karakteristiska egenskaper gör den till ett potentiellt starkt vertyg för vindenergi. Då den kan placeras på exempelvis hustak eller skyltstolpar, utan att störa närliggande omgivning, finns det många möjliga sätt att implementera och integrera den i samhällets infrastruktur. Målet med detta projekt var att undersöka den aerodynamiska prestationen för Savoniusturbiner med två blad genom att variera bladvinkeln och överlappningsförhållandet. För att jämföra de olika profilerna användes den dimensionslösa effektkoefficienten och momentkoefficienten. Dessa koefficienter beräknades i förhållande till löptalet. Studien utfördes numeriskt med 2D-simuleringar i Ansys Fluent. De partiella differentialekvationerna som beskriver flödets egenskaper, inkluderat turbulenseffekterna, löstes med Reynolds-average Navier Stokes i kombination med k-ω SST modellen. En validering utfördes genom att jämföra data med simulerade och experimentella värden av en Semi-circular profil och en Benesh profil. Studien av bladvinkel och överlappningsförhållandet utgick från en Modified Bach profil. Den mest effektiva profilen hade en bladvinkel av 130 grader och ett överlappsförhållande på 0,56. Den genererade en maximal effektkoefficient av 0,267 vid löptal 0,9. Projektet innehöll en del osäkerheter då simuleringar aldrig kan beskriva verkligheten till fullo. Den tillgängliga beräkningskapaciteten begränsade även projektet ytterligare. Trots vissa begränsningar, visar ändå utförda simuleringar att ökad bladvinkel och ökat överlappningsförhållande genererar högre effekt.<br><p>This project was conducted within Stand up for wind and Stand up for energy.</p>

La technique d'intégration des systèmes éoliens verticaux (VAWT) au service des logements individuels, collectifs et tertiaires est une approche intéressante pour les acteurs de la maitrise d'énergie pour promouvoir une utilisation rationnelle de l'énergie. Le choix de l'implantation d'une éolienne en milieu urbain est déterminé par la hauteur des bâtiments, la vitesse du vent et l'intensité de turbulence du site. Les conditions de vents sévères à faible altitude sont favorables à une implantation de VAWT. Dans certaines villes, la hauteur moyenne des bâtiments est relativement faible et ceci fait qu'en ces lieux, les VAWTs sont appréciables par rapport aux HAWTs. La mécanique des fluides numériques (CFD) est mise en œuvre pour modéliser les écoulements d'air au travers d'éoliennes et des bâtiments. Un problème CFD modélisé avec un modèle de turbulence approprié donneront des résultats de simulations qui s'approcheront des réalités physiques et des résultats de l'expérimentation. Dans cette étude, les modèles standard k-" et SST k-! ont été utilisés. Après analyse des possibilités d'intégration d'une VAWT, la toiture reste la zone d'intégration la plus intéressante. En plus de l'étude aérodynamique, nous avons entamé une modélisation électrique de la chaîne de conversion de l'éolienne en utilisant le logiciel Matlab/Simulink. Le travail a été effectué dans le but de déterminer la puissance électrique susceptible d'être produite par l'éolienne. Pour finaliser cette étude, un modèle de couplage électrique de VAWTs avec un bâtiment considéré comme un modèle de charge est présenté<br>The building integration of the vertical axis wind turbine (VAWT) to supply the individual, collective and tertiary residences consumption is an interesting approach that can help architects and the actors of the energy control to promote a rational use of renewable energy in the in homes. The choice of the location of the urban wind turbine type is determined by building height, wind speed and turbulence intensity of the site. The severe conditions of wind at low altitude are favorable for a VAWT installation. In some cities, the average buildings height is low, in these places, the VAWTs must be appreciable compared to the HAWTs. The modelling of the air flow through the wind turbine and the couple building-wind turbine involves the computation fluid dynamics (CFD). A problem modeled with a suitable turbulence model will give results that approach the physical reality and the experiment results. In this study, the standard k-" and SST k-! models were used. After analyzing the possibilities of VAWT integration, the roof is the most interesting integration area. In addition to CFD method, we have started to study the electrical model of the VAWT. The work was conducted to determine the electrical power generated by the wind turbine using Matlab/Simulink software. To complete the study, a VAWT model coupled with a building where the building is considered as a consumption model is presented

Praca doktorska podejmuje problematykę badania innowacyjnej elektrowni wiatrowej stworzonej do pracy w instalacjach przydomowych o małej mocy<br>This PhD thesis undertakes an issue of the innovative wind mill dedicated to small power plant installation for individual household use

Oblast problémů, ze kterých konkrétní téma projektu vychází, zahrnuje současnou globální transformaci zdrojů energie a jejich dodávek se zvláštní pozorností na obnovitelné zdroje energie. Důraz je kladen zejména na hodnoty jež přináší produkt určený k užívání ve veřejných prostorách. Autorovým zadáním bylo navrhnout osvětlovací jednotku nezávislou na vnějším zdroji napájení. Cílem návrhu je přehodnotit způsob, jakým jsou dnes technologie využívání sluneční a větrné energie běžně používány, a navrhnout řešení přinášející nové vlastnosti a užitné hodnoty pro přímého uživatele i celou společnost. Autor přináší návrh produktu jenž je reakcí na současné globální hrozby a příležitosti. Výsledkem projektu je návrh pouliční lampy kombinující fotovoltaický článek a větrnou turbínu s cílem získat elektrickou energii jež je dočasně akumulována a následně dodávána svítidlu. V návrhu je kladen důraz na požadavky ergonomie a estetickou hodnotu produktu. Navržené řešení znamená finanční přínos z hlediska šetření neobnovitelnými zdroji energie a případnými finančními výhodami pro investora plynoucími z provozování veřejného osvětlení. Pouliční lampa nezávislá na vnějším zdroji napájení má navíc menší negativní dopad na životní prostředí a představuje technologie využívání větrné a solární energie v přívětivé a nerušivé podobě.

Beräkningar visar att det med nuvarande befolkning och en västerländsk levnadsstandard behövs upp till sju jordklot för vår försörjning. Tillsammans förbrukar USA och Europa 2/3 av jordens resurser varav flera därtill redan är överutnyttjade. Jordens nuvarande befolkning förbrukar i dagsläget 120 % mer av jordens resurser än vad som är hållbart. Med den västerländska människans nuvarande genomsnittliga livsstil förmår jorden bara försörja en miljard innevånare på ett hållbart sätt. Ofta är energieffektiviseringar och energibesparingar de lösningar som föreslås för att lösa de problem som det medför. Naturligtvis är det viktigt att spara energi men de tekniska lösningar som finns för att energieffektivisera kan inte ensamma utgöra en lösning. Det visar sig ofta vara så att investeringar i energieffektivisering och energieffektiv teknik leder till högre istället för till lägre energianvändning. Detta kallas för Jevons paradox. Ett sätt att komma runt denna paradox är att göra konsumenter medvetna. Konsumenternas medvetenhet ökar genom att minska avståndet till produktionen. Utnyttjandet av naturresurser blir då inte något abstrakt långt borta utan en konkret verklighet som de kan förhålla sig till. Det bästa skulle därför vara att i byggsammanhang skapa små i stort sett självförsörjande enheter. Permakultur, en metod och ett sätt att tänka som ursprungligen mest handlar om odling, erbjuder verktyg för att göra denna idé till verklighet. Permakultur fokuserar på att skapa småskaliga lösningar nära den enskilda människan för just självförsörjning. Detta går att implementera i olika grad beroende på varje enskilt falls förutsättningar. Den metod som tagits fram i detta arbete går ut på att undersöka platsens och projektets aktuella förutsättningar och sedan matcha detta mot de tekniska lösningar som finns. Syftet med detta är inte enbart att skapa en fungerande teknisk lösning utan också att skapa en lösning som gör brukarna medvetna om sin egen energianvändning. Detta arbete kretsar därför i hög grad kring ett konkret exempel, Freinetskolan Tallbacken i Ljusdal. Där kommer en byggnad uppföras som arbetar med dessa principer och detta arbete visar hur de principerna också kan överföras på byggnadens energiförsörjning. Arbetet visar vilka avvägningar som gjorts i detta enskilda fall och ger därför en hjälp för den som själv vill kunna göra liknande avvägningar i ett byggprojekt.<br>Calculations show that the current population on earth and with a western life-style takes up to seven earth-like planets to sustain a sustainable lifestyle. Today Europe and the U.S. consume 2/3 of the resources on earth of which many are already over-used. The current population is overconsuming the resources on earth with 120% above the sustainable level. With the standard that the western citizen demands, the earth would only be able to house only one billion citizens in a sustainable way. The suggestion to solve this problem is mostly to invest in energy saving technologies and to invest in energy saving solutions. Of course, energy savings indeed are important but technical solutions can not alone provide a solution. It is often shown that investments in energy efficiency and in energy saving technology leads to higher instead of lower energy consumption. This is known as Jevons paradox. A way to solve this paradox is to create awareness among the energy consumers. By decreasing the distance between energy use and energy production, the awareness among the consumers is likely to increase. Thus, the use of natural resources will no longer remain difficult to grasp and feel remote but will be something everyone can relate to. When it comes to the built environment, the best solution would therefore be to utilse relatively small units with a high grade of self supply. Permaculture, which is a concept captured from the world of farming, provides tools to investigate and to make this idea real. What permaculture and the planning tools of permaculture do is that it focuses on small scale solutions close to the end users. Permaculture is also a concept that allows implementation on levels that can be adapted to every single case. This means that there can be different levels of self sufficiency in every unique project. The method that is presented in this paper focuses in investigating the conditions of the site and the project, and to find the technical solutions that fulfill the prerequisites of the actual case. The purpose is not necessarily just to create a working technical solution but to create a solution that makes the inhabitants aware of their energy use. Therefore this paper focuses a lot on a real example: The Freinet School Tallbacken in the Swedish municipality of Ljusdal. The school is about to build a sports hall and a canteen using these principles. This paper shows the considerations made in that actual case and provides therefore a model for anyone who is interested in the implementation of these principles in any other project.

碩士<br>健行科技大學<br>電機工程系碩士班<br>102<br>Savonius rotor is seldom applied in wind power generation system due to its lower output power. But the rotor with simple structure and low manufacturing cost is still worth to be studied more. Method of computational fluid dynamics simulation is applied to investigate the optimum output power, torque and power coefficient ( ) for three different configuration of Savonius rotors with the same cross section area and upstream wind speed. The tall and thin wind turbine is found to have the maximum output power and . The short and wide wind turbine has the maximum torque but the minimum . The influence caused by the circular covers at two ends of rotor was simulated and analyzed. It reveals that both the torque and power coefficient for Savonius rotor with covers are larger than that without covers. Comparison between simulation results of two- and three-dimensional models shows that the two-dimensional rotor is found to have lower torque and output power due to the height of rotor is unable to be taken into account.

碩士<br>國立交通大學<br>機械工程系所<br>104<br>In this study an experiment is conducted to investigate the possibility of improving the efficiency of extracting kinetic energy from water flow in a rectangular-channel by a Savonius rotor through installing a block upstream of the rotor in the channel. The channel is only partially blocked. The partial channel blockage intends to direct and strengthen the water flow toward the advancing blade of the rotor and meanwhile weaken the flow hitting the returning blade. A small-scale laboratory experimental system is established to test this concept. The rectangular channel is 15 cm wide and 12 cm high. In the experiment the mean water speed is varied from 0.1 to 0.8 m/s and four blocks with different shape and size are tested. To further augment the turbine rotation, the rotor is placed in a diverging section of the channel with a side wall of the channel inclined outward at angle of 15 and 30 . The experimental parameters include the water speed, rotor location, shape and size of the flow acceleration block, and diverging angle of the channel wall. The measured data for the efficiency of the power generation from the hydrokinetic energy indicate that in the straight channel the rotor performance can be increased more than 10 times by a suitable choice of the block and rotor location. Specifically, the power generation efficiency can be increased from 0.04 to 0.42. But in the side wall-diverging channel the installation of the blocks does not result in significant improvement of the rotor performance. Besides, it is noted that the rotor performance varies nonmonotonically with all experimental parameters. It is difficult to provide a simple criterion for choosing the optimal block. However, based on the streamline patterns in the channels affected by the blocks, which can be calculated numerically where there is no rotor in the channel, a suitable choice of the experimental parameters to substantially improve the rotor performance is possible. It can be concluded that the use of a flow acceleration block is effective in improving the performance of a Savonius rotor for harvesting the hydrokinetic energy.

碩士<br>國立臺北科技大學<br>能源與冷凍空調工程系碩士班<br>100<br>Wind energy have once again sparked the discussion of the use of green energy because of energy shortage and climate anomalies and recent price increases on the petroleum. Savonius wind turbine has the advantages of low noise, simple structure, low cost and didn’t influence by wind direction, etc. Forecasting the drag type wind turbine will gradually become the mainstream in wind power generation. In this work, a numerical study has been carried out for analyzing the aerodynamic performance of drag type wind turbine. The study discussed about variation of aerodynamic performance of drag type wind turbine by the variation of different governing parameters, including the overlap ratio, the separation gap, the number of buckets, and the cross-section profile. Based on the above parametric analysis, this paper provides the best profile for Savonius wind turbine. The results show that (1) as the tip speed ratio increases, the recirculating flow located at rotor center becomes larger and stronger, but the vortex near the blade tip becomes more weaken and small, which leads to the reduce in aerodynamic performance of Savonius wind turbine; (2) the overlaps of the rotor can balance the low pressure appearing on concave of blades, which will decrease recirculating region and increase aerodynamic efficiency; (3) as the separation gap decreases, the low pressure located at separation point becomes larger. This results in the lessening in ability of balancing the low pressure at concave of blades, which cannot promote aerodynamic performance; (4) the torque change in Savonius wind rotor with three blades is less than that with two blades; (5) the Savonius wind rotor with Bach-type blades and 0.15 overlap radio will have maximum power coefficient under the condition of tsr=1.25.

碩士<br>中原大學<br>工業與系統工程研究所<br>99<br>Green energy is an alternative key to fossil fuels and the future life. In oil prices led to rises in the cost of power generation and global environmental degradation, coupled with chemical fuel of human dependence on oil is high, resulting in inadequate development of other energy technologies all the circumstances. The importance of renewable energy gradually, regeneration energy technologies can contribute to clean and secure energy in the human environment. Wind energy becomes a new source of energy because of its clean, inexhaustible, low-cost and other characteristics. Our world is facing environmental changes and growing energy needs, wind energy and wind power technology can help solve these issues. In this study, the case-Savonius wind rotor of the vertical axis small wind turbine will affect the design of parts of the fan capacity wind blades as the main object of study, the extraction of blade design factors research, development can be adapted to their environment and security design of wind turbines. In this study, combining patent analysis and TRIZ theory with the collation of literature Savonius windmill to build a Savonius wind turbine blade design factors table, and draw the Savonius wind rotor blade graphics for assessment of stress. In this study, Autodesk Inventor's 3D parametric design feature to create the model diagram via the Taguchi method of orthogonal array, configured to be 18 Savonius wind rotor blade models, and use the built-in stress analysis of Autodesk Inventor environment to experiment, and get Savonius windmill blades for the deformation under different pressures and stress of the data. We calculate the average SN ratio by the resulting map for each model. The SN cytokine response analysis and variance analysis to identify the design factors of importance, and to complete a continuous Savonius windmill blade design factor extraction process. The conclusion may provide the safety basis and reference in Savonius windmill fields related to technology development and fan design.

碩士<br>建國科技大學<br>機械工程系暨製造科技研究所<br>99<br>The air pressure difference between upper and bottom of the rotors is the thrust for the rotation of traditional vertical axis Savonius-type wind turbine. The starting torque for Savonius-type wind turbine is large. However, the negative torque value can occur during the rotating process, reducing the efficiency of wind energy utilization. In this study, the rapid prototyping technology (RP) is used to produce small type Savonius helical rotor. The experimental and simulation methods are performed to explore the aerodynamic and the torque characteristics of helical rotor with different helix angles. Numerical simulation software Ansys Fluent is performed to simulate the transient flow field and aerodynamic in all cases. The low-speed wind tunnel test equipment designed in this study is used for the experimental measurement. Three helix angle of 0 degrees, 90 degrees and 180 degrees are performed in the experimental tests. The experimental results show that the helical rotor can improve the negative torque value of traditional Savonius type wind turbine during operation. The rotation speed and average torque coefficient are highest with the helix angle of 90 degrees at the wind speeds of 6,8,10,12 m/s. For the helix angle of 180 degrees, the negative torque can completely eliminate. From the simulation and experimental results, we show the design feasibility of Savonius-type helical rotor wind turbine.

碩士<br>建國科技大學<br>機械工程系暨製造科技研究所<br>101<br>ABSTRACT For vertical axis Savonius wind turbine, the starting velocity is low and the output torque is high. The advantages for Savonius wind turbine include the simple structure, low cost and no fixed wind direction. and it is getting more attention recently. In this study, the experimental and simulation methods are performed to investigate the aerodynamic, the torque coefficient and output power coefficient with different values of blade overlap ratio and tip speed ratio. By means of experimental method, the blades of Savonius wind turbine are manufactured. Incorporating the wind tunnel and torque measurement equipment system, the rotating speed of and the torque of wind turbine are measured. The numerical software Ansys Fluent is also used to simulate the transient flow field and aerodynamic in all cases. The experimental results show that the vortex at the center of wind turbine becomes larger and the swirling flow becomes small at the blade tip with the tip speed ratio. With the overlap of blades, the vortex at the center of wind turbine becomes small and it increased the aerodynamics of wind turbine. In addition, the torque coefficient decreases with increase of tip Speed ratio. When the overlap ratio is 0.2 and the tip speed ratio is 1.2, the maximum of power coefficient is 0.23. The simulation results are quite consistent with those of experiments. Keywords: Savonius, computational fluid dynamics, overlap ratio, torque coefficient, power coefficient

碩士<br>國立交通大學<br>機械工程學系<br>100<br>This study establishes a four two-bladed Savonius wind rotors system in parallel matrix which is installed at an open field, to generate electric power. Moreover, It employs a computational fluid dynamics (CFD) software, Fluent, to analyze the flow fields and system performance. It can be separated into two sections: effect of curtain and effect of battery. The experiments detect various wind velocity, wind direction and rotational speed of wind rotors to observe the relationship between tip-speed ratio (TSR) and power coefficient (Cp). Finally, compare and analyze the results between experiment and numerical simulation. For the numerical simulate results, the maximum Cp value of system without curtain is 0.262 at TSR 0.8; the system with curtain is 0.270 at TSR 0.8 which is 1.03 times higher than system without curtain. However, the maximal difference is happened at TSR 0.6 which is 1.16 times higher than system without curtain. From Cp to TSR diagram know that the effect of curtain especially enhance performance at low TSR. On the other hand, the experimental results show that the wind velocity, wind direction and rotational speed of wind rotors have large fluctuation in open field. Therefore, we receive the relationship between Cp and TSR by repeating measuring. Same as the simulation results, curtain indeed improve the performance of system. Otherwise, the experiment of withdrawing battery at second side of circuit shows that battery is no help for progress system performance (Cp) but cause voltage oscillation. Look into the future; improve the power generated efficiency of wind rotor system and connect system to local grid to have more benefit utilize.

碩士<br>國立交通大學<br>機械工程系所<br>102<br>This study employs a computational fluid dynamics (CFD) software, Fluent, to analyze the flow fields around two-bladed Savonius wind rotors and their corresponding performances. This research includes three cases: the first one is a study of a single Savonius wind rotor, the second is the parallel matrix system, consisting of four two-bladed Savonius wind rotors, and the last one is the parallel matrix system of ten two-bladed Savonius wind rotors. All of the cases are carried out by the corresponding parametric studies, whose parameters include the wind velocity and tip speed ratio. After that, the influence of wind direction change on the parallel system is also studied. Then, comparisons between the systems mentioned above are discussed. The simulation results show that the maximum Cp value of one single Savonius wind rotor is 0.191 at tip-speed ratio 0.8; the parallel matrix system with four Savonius wind rotors is 0.402 at tip-speed ratio 0.9; the parallel matrix system with ten Savonius wind rotors is 0.438 at tip-speed ratio 0.7. The average Cp of the parallel matrix system with ten Savonius wind rotors is 2.25 times higher than that in one single Savonius wind rotor and the average Cp of the parallel matrix system with four Savonius wind rotors is 2.07 times higher than that in one single Savonius wind rotor. However, the average Cp of the parallel matrix system with ten Savonius wind rotors is 1.08 times higher than that in the parallel matrix system with four Savonius wind rotors. The Cp of these three cases slightly increase with wind speeds at the same tip speed ratio. The higher performance of parallel matrix system is resulted from the positive interaction between these Savonius wind rotors, and the flow fluctuation plays the major role in contributing to this effect, but this effect is strongly influenced by the change of wind direction. When wind direction is 0°, the Cp of the parallel matrix system becomes almost the same or even lower than that of a single one.