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1
Pearson, Charlie. "Vertical axis wind turbine acoustics." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245256.
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Increasing awareness of the issues of climate change and sustainable energy use has led to growing levels of interest in small-scale, decentralised power generation. Small-scale wind power has seen significant growth in the last ten years, partly due to the political support for renewable energy and the introduction of Feed In Tariffs, which pay home owners for generating their own electricity. Due to their ability to respond quickly to changing wind conditions, small-scale vertical axis wind turbines (VAWTs) have been proposed as an efficient solution for deployment in built up areas, where the wind is more gusty in nature. If VAWTs are erected in built up areas they will be inherently close to people; consequently, public acceptance of the turbines is essential. One common obstacle to the installation of wind turbines is noise annoyance, so it is important to make the VAWT rotors as quiet as possible. To date, very little work has been undertaken to investigate the sources of noise on VAWTs. The primary aim of this study was therefore to gather experimental data of the noise from various VAWT rotor configurations, for a range of operating conditions. Experimental measurements were carried out using the phased acoustic array in the closed section Markham wind tunnel at Cambridge University Engineering Department. Beamforming was used in conjunction with analysis of the measured sound spectra in order to locate and identify the noise sources on the VAWT rotors. Initial comparisons of the spectra from the model rotor and a full-scale rotor showed good qualitative agreement, suggesting that the conclusions from the experiments would be transferable to real VAWT rotors. One clear feature observed in both sets of spectra was a broadband peak around 1-2kHz, which spectral scaling methods demonstrated was due to laminar boundary layer tonal noise. Application of boundary layer trips to the inner surfaces of the blades on the model rotor was found to eliminate this noise source, and reduced the amplitude of the spectra by up to 10dB in the region of the broadband peak. This method could easily be applied to a full-scale rotor and should result in measurable noise reductions. At low tip speed ratios (TSR) the blades on a VAWT experience dynamic stall and it was found that this led to significant noise radiation from the upstream half of the rotor. As the TSR was increased the dominant source was seen to move to the downstream half of the rotor; this noise was thought to be due to the interaction of the blades in the downstream half of the rotor with the wake from the blades in the upstream half. It was suggested that blade wake interaction is the dominant noise source in the typical range of peak performance for the full-scale QR5 rotor. Different solidity rotors were investigated by using 2-, 3- and 4-bladed rotors and it was found that increasing the solidity had a similar effect to increasing the TSR. This is due to the fact that the induction factor, which governs the deflection of the flow through the rotor, is a function of both the rotor solidity and the TSR. With a large body of experimental data for validation, it was possible to investigate computational noise prediction methods. A harmonic model was developed that aimed to predict the sound radiated by periodic fluctuations in the blade loads. This model was shown to agree with similar models derived by other authors, but to make accurate predictions very high resolution input data was required. Since such high resolution blade loading data is unlikely to be available, and due to the dominance of stochastic sources, the harmonic model was not an especially useful predictive tool. However, it was used to investigate the importance of the near-field components of the sound radiated by the wind tunnel model to the acoustic array. It was shown that the near-field terms were significant over a wide range of frequencies, and the total spectrum was always greater than that of the far-field component. This implied that the noise levels measured by the acoustic array represented an upper bound on the sound radiated to the far-field, and hence that the latter would also be dominated by stochastic components. An alternative application of the harmonic model, which attempted to determine the blade loading harmonics from the harmonics in the sound field was proposed. This inversion method utilised a novel convex optimisation technique that was found to generate good solutions in the simulated test cases, even in the presence of significant random noise. The method was found to be insensitive at low frequencies, which made it ineffective for inverting the real microphone data, although this was shown to be at least partly due to the limitations imposed by the array size. In addition to the harmonic models, an empirical noise prediction method using the spectral scaling laws derived by \citet*{Brooks_1989} was trialled, and was found to be capable of making predictions that were in agreement with the measured data. The model was shown to be sensitive to the exact choice of turbulence parameters used and was also found to require good quality aerodynamic data to make accurate noise predictions. If such data were available however, it is expected that this empirical model would be able to make useful predictions of the noise radiated by a VAWT rotor.
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Hikkaduwa, Vithanage Ajith. "DESIGN AND PERFORMANCE ANALYSIS OF PITCHED-PLATE VERTICAL AXIS WIND TURBINE FOR DOMESTIC POWER GENERATION." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17428.
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Wind energy is identified a promising energy resource in Sri Lanka. Therefore, it is important to use proper technologies for efficient energy capturing in order to minimize cost of energy. Small scale wind turbines are usually installed in constricted places (particularly in urban areas) where wind flow is turbulent and difficult to predict. Savonious type vertical axis wind turbines are important due to several reasons such as good response to turbulent winds, high initial torque, low cost, low noise, less maintenance.In this study, a modified flat plate type Savonius wind rotor was proposed to cost effectively harness wind energy in constricted places. Generally, vertical axis wind turbines (VAWT) are less efficient than horizontal axis wind turbines, one reason behind this issue is wind force difference between the 2 sides of the axis is small and due to this reason torque is small and power generation capacity is less.A prototype of the proposed VAWT was fabricated and the performance was determined by acquiring experimental data. Artificial wind blow which was generated by a huge fan was used to measure rotational speed and torque characteristics at varying wind speeds. Data were collected with 1-second sampling time and a data acquisition system was developed under this study. In the proposed design one side of the turbine blades are facing the wind direction in order to capture maximum force while other side is edging the blades to have minimum opposite torque. With this concept it is expected to maximize the torque of the axis and generate more power. A sort of a passive pitch mechanism is therefore utilized in order to save energy and simplify the system. Turbine blades are simple flat plates and it eliminates usage of complex aero foils. Due to the simplicity of this design it would be possible to use this turbine for domestic electricity generation at affordable costs.Nowadays, net metering systems are being promoted in Sri Lanka and it would be beneficial to introduce low cost VAWT which operates at low winds as well as turbulent wind conditions. Based on typical household hourly load profile, viability of proposed vertical axis wind turbine was evaluated by considering rural and urban wind regimes in Sri Lanka. The costs of wind energy at two selected locations were determined in the context of net metering.
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Bülow, Fredrik. "A Generator Perspective on Vertical Axis Wind Turbines." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-197855.
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The wind energy conversion system considered in this thesis is based on a vertical axis wind turbine with a cable wound direct drive PM generator. Diode rectifiers are used to connect several such units to a single DC-bus and a single inverter controls the power flow from the DC-bus to a utility grid. This work considers the described system from a generator perspective i.e. the turbine is primarily seen as a torque and the inverter is seen as a controlled load. A 12 kW VAWT prototype with a single turbine has been constructed within the project. The power coefficient of this turbine has been measured when the turbine is operated at various tip speed ratios. This measurement determines both how much energy the turbine can convert in a given wind and at what speed the turbine should be operated in order to maximise the energy capture. The turbine torque variation during the revolution of the turbine has also been studied. A PM generator prototype has been constructed in order to study power loss in the stator core at low electrical frequencies. Heat exchange between the stator and the air-gap between the stator and the rotor has been studied. Heat exchange between the stator and the air-gap is increased by turbulence caused by the rotor. The generator was also used in a demonstration of a DC-grid where two diode rectified PM generators supplied power to a single DC load. An initial study of an inverter suitable for grid connection of the 12 kW PM generator has been performed. Several turbine control strategies are evaluated in simulations. The control strategies only require the parameter "turbine speed" to determine the optimal system load.
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D'Ambrosio, Marco, and Marco Medaglia. "Vertical Axis Wind Turbines: History, Technology and Applications." Thesis, Halmstad University, Halmstad University, School of Business and Engineering (SET), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4986.
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In this Master Thesis a review of different type of vertical axis wind turbines (VAWT) and a preliminary investigation of a new kind of VAWT are presented.
After an introduction about the historical background of wind power, the report deals with a more accurate analysis of the main type of VAWT, showing their characteristics and their operations. The aerodynamics of the wind turbines and a review of different type on generators that can be used to connect the wind mill to the electricity grid are reported as well.
Several statistics are also presented, in order to explain how the importance of the wind energy has grown up during the last decades and also to show that this development of the market of wind power creates new opportunity also for VAWT, that are less used than the horizontal axis wind turbine (HAWT).
In the end of 2009 a new kind of vertical axis wind turbine, a giromill 3 blades type, has been built in Falkenberg, by the Swedish company VerticalWind. The tower of this wind turbine is made by wood, in order to get a cheaper and more environment friendly structure, and a direct driven synchronous multipole with permanent magnents generator is located at its bottom. This 200 kW VAWT represents the intermediate step between the 12 kW prototype, built in collaboration with the Uppsala University, and the common Swedish commercial size of 2 MW, which is the goal of the company.
A preliminary investigation of the characteristics of this VAWT has been done, focusing in particular on the value of the frequency of resonance of the tower, an important value that must be never reached during the operative phase in order to avoid serious damage to all the structure, and on the power curve, used to evaluate the coefficient of power (Cp) of the turbine. The results of this investigation and the steps followed to get them are reported. Moreover a energy production analysis of the turbine has been done using WindPro, as well as a comparison with and older type on commercial VAWT.
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Möllerström, Erik. "Vertical Axis Wind Turbines : Tower Dynamics and Noise." Licentiate thesis, Högskolan i Halmstad, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-242267.
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Vertical axis wind turbines (VAWTs) have with time been outrivaled by the today common and economically feasible horizontal axis wind turbines (HAWTs). However, VAWTs have several advantages such as the possibility to put the drive train at ground level, lower noise emissions and better scaling behavior which still make them interesting for research. The work within this thesis is made in collaboration between the Department of Construction and Energy Engineering at Halmstad University and the Division for Electricity at Uppsala University. A 200 kW VAWT owned by the latter and situated close to Falkenberg in the southwest of Sweden has been the main subject of the research even if most learnings has been generalized to fit a typical vertical turbine. This particular turbine has a wooden tower which is semi-guy-wired, i.e. the tower is both firmly attached to the ground and supported by guy-wires. This thesis has two main topics both regarding VAWTs: eigenfrequency of the tower and the noise generated from the turbine. The eigenfrequency of a semi-guy-wired tower is studied and an analytical expression describing this is produced and verified by experiments and simulations. The eigenfrequency of the wire itself and how it is affected by wind load are also studied. The noise characteristics of VAWTs have been investigated, both theoretically and by noise measurement campaigns. Both noise emission and frequency distribution of VAWTs has been studied. The work has resulted in analytical expressions for tower and wire eigenfrequency of a semi-guy-wired tower as well as recommendations for designing future towers for VAWTs. The noise emission of VAWTs has been studied and proven low compared to HAWTs. The noise frequency distribution of the 200 kW VAWT differs significantly from that of a similar size HAWTs with for example lower levels for frequencies below 3000 Hz.
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Almohammadi, Khaled Mohammad. "Optimization of a CFD based design of a straight blade vertical axis wind turbine (SB-VAWT)." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7021/.
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Enhancing the extraction of the wind energy in urban regions using micro and small wind turbines becomes a necessity with the increasing power consumption. The focus of this thesis is to optimize micro and small SB-VAWT performance by analysing CFD techniques, several modelling characteristics and design parameters where the performance is measured by the power coefficient. In this thesis, the SB-VAWT is optimized by employing sophisticated optimization techniques, namely such as the GA and the NLPQL, which are employed on response surfaces created from several design sampling methods. The optimization is based on three parameters, namely, camber, thickness and chord. A novel airfoil geometry has been introduced. The new airfoil geometry increases the power coefficient by about 42% at the optimized tip speed ratio and increases the peak of the turbine power coefficient by 4% at a low tip speed ratio. However, it was necessary to assess the computational process by examining the mesh and the computational method in order to ensure that the optimized design of the SB-VAWT is only resulting from the optimization process. Therefore, several physical phenomena have been investigate including the dynamic stall, laminar-turbulent transition and laminar bubbles. Also, several computational techniques and schemes have been critically analysed. Further, several mesh independency techniques have been implemented and it was found that the fitting method may be suitable for SB-VAWTs due to the presence of oscillations in the convergence of the power coefficient which may be caused by the presence of dynamic stall, laminar-turbulent transition and laminar bubbles. The physics of these flow conditions are only captured when the transitional model is employed. The optimization of the SB-VAWT in this thesis is based on a 2D model. It was found that the 2D model produce a results similar to the 3D model at mid span of the turbine blade. Therefore, the 2D model of the turbine sufficiently represents the flow physics around the blades qualitatively, and thus the 2D model is employed for the optimization of the SB-VAWT.
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Zhao, Jiaming. "Experimental Study of Effects of Leading-Edge Structures on the Dynamic Stall of a Vertical Axis Wind Turbine Airfoil." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/32053.
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Vertical axis wind turbine, developed as one of the main methods to utilize the wind energy, has a promising future; however, the major issue to limit its performance is the uneven loading on the blade during operation. Flow control mechanisms have been employed in the aerodynamic field to improve the performance of airfoils. In this study, two types of leading-edge structures, including flexible leading-edge and leading-edge roughness, are experimentally investigated to analyze their effects on altering the aerodynamic characteristics of NACA 0018 airfoil under steady flow condition and dynamic pitching condition. Current experimental results indicate that 1) during the steady flow condition, both of leading-edge structures contribute to the delay of the static stall; 2) for the dynamic pitching process, the leading-edge structures either delayed the dynamic stall angle or increased the area of the coefficient of pressure loop as a function of angle of attack.
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Kjellin, Jon. "Vertical Axis Wind Turbines : Electrical System and Experimental Results." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182438.
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The wind power research at the division of Electricity at Uppsala University is aimed towards increased understanding of vertical axis wind turbines. The considered type of wind turbine is an H-rotor with a directly driven synchronous generator operating at variable speed. The experimental work presented in this thesis comprises investigation of three vertical axis wind turbines of different design and size. The electrical, control and measurement systems for the first 12 kW wind turbine have been designed and implemented. The second was a 10 kW wind turbine adapted to a telecom application. Both the 12 kW and the 10 kW were operated against dump loads. The third turbine was a 200 kW grid-connected wind turbine, where control and measurement systems have been implemented. Experimental results have shown that an all-electric control, substituting mechanical systems such as blade-pitch, is possible for this type of turbine. By controlling the rectified generator voltage, the rotational speed of the turbine is also controlled. An electrical start-up system has been built and verified. The power coefficient has been measured and the stall behaviour of this type of turbine has been examined. An optimum tip speed ratio control has been implemented and tested, with promising results. Use of the turbine to estimate the wind speed has been demonstrated. This has been used to get a faster regulation of the turbine compared to if an anemometer had been used.
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Möllerström, Erik. "Noise, eigenfrequencies and turbulence behavior of a 200 kW H-rotor vertical axis wind turbine." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316385.
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Vertical-axis wind turbines (VAWTs) have with time been outrivaled by the today more common and economically feasible horizontal-axis wind turbines (HAWTs). However, VAWTs have several advantages which still make them interesting, for example, the VAWTs can have the drive train at ground level and it has been argued that they have lower noise emission. Other proposed advantages are suitability for both up-scaling and floating offshore platforms. The work within this thesis is made in collaboration between Halmstad University and Uppsala University. A 200-kW semi-guy-wired VAWT H-rotor, owned by Uppsala University but situated in Falkenberg close to Halmstad, has been the main subject of the research although most results can be generalized to suit a typical H-rotor. This thesis has three main topics regarding VAWTs: (1) how the wind energy extraction is influenced by turbulence, (2) aerodynamical noise generation and (3) eigenfrequencies of the semi-guy-wired tower. The influence from turbulence on the wind energy extraction is studied by evaluating logged operational data and examining how the power curve and the tip-speed ratio for maximum Cp is impacted by turbulence. The work has showed that the T1-turbine has a good ability to extract wind energy at turbulent conditions, indicating an advantage in energy extraction at turbulent sites for VAWTs compared to HAWTs.The noise characteristics are studied experimentally, and models of the two most likely aerodynamic noise mechanisms are applied. Here, inflow-turbulence noise is deemed as the prevailing noise source rather than turbulent-boundary-layer trailing-edge noise (TBL-TE) which is the most important noise mechanism for HAWTs. The overall noise emission has also been measured and proven low compared to similar sized HAWTs. The eigenfrequencies of a semi-guy-wired tower are also studied. Analytical expressions describing the first-mode eigenfrequency of both tower and guy wire has been derived and verified by experiments and simulations.
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Bah, Elhadji Alpha Amadou. "Numerical investigation on the use of multi-element blades in vertical-axis wind turbines." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53501.
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The interest in sustainable forms of energy is being driven by the anticipated scarcity of traditional fossil fuels over the coming decades. There is also a growing concern about the effects of fossil fuel emissions on human health and the environment. Many sources of renewable energy are being researched and implemented for power production. In particular, wind power generation by horizontal- and vertical-axis wind turbines is very popular.
Vertical-axis wind turbines (VAWTs) have a relative construction simplicity compared to horizontal-axis wind turbines (HAWTs). However, VAWTs present specific challenges that may hinder their performance. For instance, they are strongly affected by dynamic stall. A significant part of the kinetic energy contained in the oncoming wind is lost in swirl and vortices. As a result, VAWTs have lower power production compared to HAWTs.
First, the present work is aimed at the study of the aerodynamics of straight-bladed VAWTs (SB-VAWTs). Empirical calculations are conducted in a preliminary work. Then a two-dimensional double multiple streamtube (DMST) approach supported by a two-dimensional numerical study is implemented. The dynamic stall and aerodynamic performance of the rotor are investigated. A VAWT-fitted dynamic stall model is implemented. Computational fluid dynamics (CFD) simulations are conducted to serve as reference for the DMST calculations. This three-pronged approach allows us to efficiently explore multiple configurations. The dynamic stall phenomenon is identified as a primary cause of performance loss.
The results in this section validate the DMST model as a good replacement for CFD analysis in early phase design provided that a good dynamic stall model is used.
After having identify the primary cause of performance loss, the goal is to investigate the use to dual-element blades for alleviating the effect of dynamic stall, thereby improving the performance of the rotor. The desirable airfoil characteristics are defined and a parametric analysis conducted. In the present study the parameters consists of the size of the blade elements, the space between them, and their relative orientation. The performance of the rotor is calculated and compared to the baseline.
The results highlight the preeminence of the two-element configuration over the single-element provided that the adequate parametric study is conducted beforehand.
A performance enhancement is obtained over a large range of tip speed ratios. The starting characteristics and the operation stability are also improved.
Finally, an economic analysis is conducted to determine the cost of energy and thus the financial viability of such a project. The Great Coast of Senegal is selected as site of operation. The energy need and sources of this region are presented along with its wind energy potential. The cost evaluation shows the economic viability by comparing the cost of energy to the current energy market prices.
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Gonzalez, Campos Jose Alberto. "Design and Experimentation of Darrieus Vertical Axis Wind Turbines." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1594690510943748.
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Rastegar, Damoon. "Modification of Aeroelastic Model for Vertical Axes Wind Turbines." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3388.
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In wind turbines, flow pressure variations on the air-structure interface cause aerodynamic forces. Consequently the structure deforms and starts to move. The interaction between aerodynamic forces and structural deformations mainly concerns aeroelasticity. Since these two are coupled, they have to be considered simultaneously in cases which the deformations are not negligible in comparison to the other geometric dimensions. The purpose of this work is to improve the simulation model of a vertical axis wind turbine by modifying the structural model from undamped Euler-Bernoulli beam theory with lumped mass matrix to the more advanced Timoshenko beam theory with consistent mass matrix plus an additional damping term. The bending of the beam is then unified with longitudinal and torsional deformations based on a fixed shape cross-section assumption and the Saint-Venant torsion theory. The whole work has been carried out by implementing the finite element method using MATLAB code and implanting it in a previously developed package as a complement. Finally the results have been verified by qualitative comparisons with alternative simulations.
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Kazlova, Ala, and Bettina Ullmann. "When Wind Goes Vertical: : Can a start-up company make use of its born global potential to revolutionize the wind turbine industry?" Thesis, Linnéuniversitetet, Ekonomihögskolan, ELNU, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-6605.
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The 21st century would be a nightmare for Don Quijote: thousands of windmills are installed all over the globe and the number will increase tremendously over the next years. If climate change was an issue in the early 17th century, Don Quijote might have specialized in fighting nuclear or fossil fuel power plants. The change in power production is clearly pronounced, and it inspires the market to respond immediately. Numerous wind turbine manufacturers emerge, developing one technological innovation after another. The trend clearly goes in one direction: horizontal axis wind turbines in all possible variations. However, there are a few companies that do not follow the mainstream – they swim against the current and introduce new concepts, with the potential to set new standards in the industry. Nevertheless, the question whether these companies can establish operations and survive in an industry dominated by large multinational corporations arises. If these companies want to become recognized, they need to compete on an international scale from the outset – they become born globals. This master’s thesis investigates the preconditions under which an innovative start-up company can become born global in the wind turbine industry. For that, distinctive resources and capabilities of such companies, as well as key success factors for the industry are defined. Furthermore, enhancing or restricting parameters lying within company’s environment – in particular, within its networks – are discovered. These findings are based on and supported by the case study of an innovative vertical axis wind turbine manufacturer. In addition, the influence of this company’s university spin-off origin is investigated.
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Christoffer, Fjellstedt. "Simulations of vertical axis wind turbines with PMSG and diode rectification to a mutual DC-bus." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-323735.
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Transient simulations were performed with MATLAB Simulink on a mutual wind park topology, where three vertical axis wind turbines equipped with permanent magnet synchronous generators were connected to a mutual DC-bus through passive diode rectification. The aim with the work was to show the effects of two different kinds of loads on the system in respect to generator torque, rotor speed, produced power by the generators and the power on the DC-bus. The loads were a variable voltage source and a resistance with the value 2.0 Ω. It was shown that the transient behavior of the system in respect to both kinds of loads exhibited a high level of stability when the wind speed was altered. It was also shown that the system when equipped with a voltage source load began to oscillate with the natural frequency of a two mass rotating spring system if a sudden increase of the voltage made the DC-bus voltage larger than the peak of the internal induced voltage of the generators. Small variations of the DC voltage however exhibited a stable behavior.
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Jaohindy, Placide. "Modélisation des systèmes éoliens verticaux intégrés aux bâtiments : modélisation du couple production / Bâtiment." Thesis, La Réunion, 2012. http://www.theses.fr/2012LARE0005/document.
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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 présentéThe 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
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Shaheen, Mohammed Mahmoud Zaki Mohammed. "Design and Assessment of Vertical Axis Wind Turbine Farms." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439306478.
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Weiss, Samuel Bruce. "Vertical axis wind turbine with continuous blade angle adjustment." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/65178.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 26).
The author presents a concept for a vertical axis wind turbine that utilizes each blade's entire rotational cycle for power generation. Each blade has its own vertical axis of rotation and is constrained to rotate at the rate of one half of a revolution per full revolution of the rotor. For a rotor of radius r and blades of width b, a technical analysis predicts a theoretical maximum power coefficient of CP = b 2r+b, neglecting wind flow interference by upwind blades. This theoretical power coefficient is generally greater than the efficiency of a typical Savonius wind turbine (CP ~~ 0.15), and it reaches CP = 0.5 at the limiting blade width, b = 2r. The analysis also predicts a static torque and optimal tip-speed ratio that are both greater than those of a Savonius wind turbine with similar blade dimensions. Design considerations for implementing the kinematic constraint and for blade adjustment to account for changes in wind direction are discussed, and the author's prototype is presented. Testing of the prototype demonstrated that implementation of the kinematic constraint is feasible, and that efficiencies greater than those achievable by a Savonius turbine are plausible. In 4 m s wind conditions, the prototype yielded an estimated CP of 0.15, with much room for improvement through design changes and blade optimization in future iterations of this style of turbine.
by Samuel Bruce Weiss.
S.B.
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Ottino, Gabriele. "Two approaches to the study of detached flows." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13786/document.
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On étudie des phénomènes de séparation d'écoulement avec deux approches différentes. Dans la première partie, on considère des écoulements 2D, instationnaires, incompressibles et non visqueux. Un modèle analytique-numérique, basé sur la jonction d'une transformation conforme et d'une méthode aux tourbillons ponctuels, est construit pour définir l'écoulement potentiel dans un domaine doublement connecté où les corps sont caractérisés par une variation temporelle de leur circulation. En particulier, on s'intéresse à l'étude de l'écoulement autour d'un VAWT avec deux pales. Dans la seconde partie on considère des écoulements visqueux et compressibles. On construit un solveur qui résoud les équations de Navier-Stokes en y introduisant une technique de pénalisation: les corps sont modélisés comme des milieux poreux ayant une porosité très petite par rapport à la porosité du fluide extérieur. Cette technique permet d'utiliser des maillages cartésiens pour des géométries très complexesIn the present work flow separation phenomena are investigated by means of two different approaches. In the first part, 2D unsteady incompressible inviscid flows are studied. An analytical-numerical model, based on the conjunction of a conformal mapping and a point vortex method, is built to define the potential flow field in a doubly connected domain where bodies are characterized by a variation in time of their circulation. In particular, the study of the unsteady flow past a 2-blade Darrieus VAWT is addressed. Until now the study of vortex motions has only been described in doubly-connected flow fields where the circulations have a constant null value. The flow field here analysed has a deep unsteadiness, which determines the circulations varying in time: so a technique is developed to uniquely define the circulations around the bodies. Three conditions result necessary to be imposed: in addition to the two Kutta conditions at the trailing edges, another one has to be imposed in order to respect the Kelvin theorem. With a classical configuration, this machine, experiencing angles of attack of opposite values, gives rise to complex vortex shedding phenomena that reduce its performances and stress its structure. In order to control the flow separation from the blades, an innovative solution is qualitatively investigated which consists of taking blade profiles provided with vortex trapping cavities. Interesting results are obtained, even if in the limit of inviscid flow. In the second part compressible viscous flows are taken into account. A fully Navier-Stokes equations solver is implemented introducing the penalization technique. The idea is to replace the bodies by the fluid, in a way that also into the bodies the penalized Navier-Stokes equations remain valid, respecting the boundary conditions on their contours. Starting from this purpose, the bodies are considered as porous media with a little porosity with respect to that of the external flow, which tends to infinity. This technique allows simple Cartesian meshes to be used, also for very complex geometries like those of industrial interest. The resulting code is tested on different flow fields, both steady and unsteady, both subsonic and supersonic, obtaining always a good agreement with other theoretical and numerical results described in literature
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Rynkiewicz, Mateusz. "Design of PM generator for avertical axis wind turbine." Thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177309.
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The task in this project is to design a generator for a vertical axis wind turbine withpower rated to 20kW at a wind speed of 10m/s. The project is conducted at theDivision of Electricity at Uppsala University with collaboration from ElectricGeneration AB. The design has just a few moving parts, which decreases maintenancecosts and increases its toughness. The turbine absorbs wind from every direction butits rotation speed ratio is lower than horizontal axis wind turbines. It means that thegenerator must be bigger and therefore more expensive. Price is an importantcriterion for the generator. Neodymium magnets are expensive so the amount of thismaterial must be limited.Several designs have been simulated but one final design has proven the mostpromising. It fulfills all specifications such as efficiency above 95%, 20kW outputpower and it also has a relatively low amount of hard magnetic material.A design with a single row of cables per slot was decided upon to eliminate heatpockets between cable rows, which can occur in designs with two cable rows perslot. It would be interesting to study designs with two or more cable rows per slot, asit could lead to a smaller and more efficient machine.
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Robotham, Antony John. "The aerodynamic control of the V-type vertical axis wind turbine." n.p, 1989. http://ethos.bl.uk/.
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Norström, Parliden Jonas, and Mateusz Rynkiewicz. "Design of PM generator for a vertical axis wind turbine." Thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-180910.
Full textAbstract:
The task in this project is to design a generator for a vertical axis wind turbine withpower rated to 20kW at a wind speed of 10m/s. The project is conducted at theDivision of Electricity at Uppsala University with collaboration from ElectricGeneration AB. The design has just a few moving parts, which decreases maintenancecosts and increases its toughness. The turbine absorbs wind from every direction butits rotation speed ratio is lower than horizontal axis wind turbines. It means that thegenerator must be bigger and therefore more expensive. Price is an importantcriterion for the generator. Neodymium magnets are expensive so the amount of thismaterial must be limited.Several designs have been simulated but one final design has proven the mostpromising. It fulfills all specifications such as efficiency above 95%, 20kW outputpower and it also has a relatively low amount of hard magnetic material.A design with a single row of cables per slot was decided upon to eliminate heatpockets between cable rows, which can occur in designs with two cable rows perslot. It would be interesting to study designs with two or more cable rows per slot, asit could lead to a smaller and more efficient machine.
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Colley, Gareth. "Design, operation and diagnostics of a vertical axis wind turbine." Thesis, University of Huddersfield, 2012. http://eprints.hud.ac.uk/id/eprint/17547/.
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The need for sustainable energy sources becomes greater each year due to the continued depletion of fossil fuels and the resulting energy crisis. Solutions to this problem are potentially in the form of wind turbines which have been receiving increased support at a micro level. At present a number of wind turbines are being developed that are of cross-flow vertical axis operation which have shown significant increases in performance compared to existing technologies. From an extensive literature review a number of key issues have been highlighted which are concerned with design, operation and diagnostics of this new wind power technology which have been used to formulate the scope of this research. A design procedure for a cross-flow machine that features both a multi-blade rotor and fixed outer stator guide vanes has been derived in which both rotor and stator blade profiles have been generated for a low wind speed urban application. Using these blade profiles a prototype wind turbine has been fabricated and used for full scale development testing. In the presented work both experimental and numerical investigations have been carried out to determine the operational characteristics of this new technology. The experimental data obtained under controlled laboratory conditions has been used to validate a Computational Fluid Dynamic (CFD) model which has been used throughout. A flow field analysis of the machine has highlighted large asymmetries in both pressure and velocity about the central axis of the machine in both stationary and rotating frames of reference. This has identified primary inefficiencies within the design which limit the torque generating capability of the rotor due to blockage effects and downstream blade interactions. This asymmetry has been quantified in the form asymmetry ratio and used to determine downstream rotor effects and the optimum location of multiple wind turbines which is seen to be x/D >10 in order to minimize performance reductions. The torque and power generation capabilities of the machine have been characterised at both 'design' and ‘offdesign' conditions in which individual blade torque contributions have been quantified. This has highlighted specific energy transfer zones within the turbine namely at a few key blades on the windward side of the rotor. It has also shown counter-rotating torques generated on the leeward side of the machine at specific blade positions during the cycle. Overall performance has been quantified in which a maximum CT = 1.7 and CP = 0.24 has been observed which has some similarities to the Savonius rotor. Geometric effects on torque and power response have been quantified in which a strong dependence on stator blade number is noticed. Further, maximum performance output of the machine is generated at the baseline design condition. Using torque response data a multiple regression model has been developed in which a design equation for crossflow rotor torque has been derived which can be used during the conceptual design phase. Finally, the effectiveness of a two-dimensional transient CFD model to predict cross-flow wind turbine rotor blade loss has been evaluated against full scale experimental data. It has shown that from analysis in the frequency domain specific blade faults can be recognised which agrees well with experimental data obtained. The use of this model for wind turbine performance emulation has been described.
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Mewburn-Crook, Anthony. "The design and development of an augmented vertical axis wind turbine." Thesis, Kingston University, 1990. http://eprints.kingston.ac.uk/20541/.
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The augmented vertical axis wind turbine resulted from a survey of the problems of existing wind turbines, and the identification of the design criteria that it should be inherently safe and reliable. It should be self-starting in low winds and continue to run in high Winds, and it should be environmentally acceptable. The design consisted of a vertical axis rotor, with five vertical and five horizontal blades, surrounded by an augmentor which contained eight converging stators and a dome desigried to increase the flow rate through the rotor, and to decrease the pressure at exit from the rotor. Extensive model tests showed that the wind turbine had attractive operating characteristics, which were confirmed by a prototype machine with a 6m diameter rotor rated at 10kW. However, a detailed analysis of the design and costs showed that it was too expensive. An analysis of an idealised augmented vertical axis wind turbine showed that there was potential for increasing the performance and decreasing costs. Measurements of the detailed flow field through the rotor and around the augmentor demonstrated that augmentation was by means of an increased pressure drop across the rotor, combined with an increased mass flow rate through it. The efficiency of the upstream part of the rotor was also increased by the augmentor. The benefits of turbulent mixing in the wake of the turbine between the external flowfield and the flow through the turbine were also recognised. Major modifications to the design of the augmentor and rotor resulted in two types of wind turbine which maintained the attractive operating characteristics and appeared to be commercially viable. The designs offer particular benefits in terms of inherent safety and reliability. The potential of cost effective, large multi¬megawatt machines is also recognised. The work has also provided further insight into wind turbine augmentation, and in the design and development of vertical axis rotors.
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Robotham, A. J. "The aerodynamic control of the V-type vertical axis wind turbine." Thesis, Open University, 1989. http://oro.open.ac.uk/57284/.
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The V-type vertical axis wind turbine (V-VAWT) is of simple design and construction, has a low aerodynamic efficiency, yet its originators consider that it will be a cost effective configuration in electricity generation applications. However, the quality and reliability of its power output must be ensured; this necessarily requires continual control of rotor speed and power. The initial V-VAWT investigations of Sharpe and Taylor, and methods of wind turbine control are reviewed. Partial-span pitch angle variation is considered the most promising option, and the systematic investigation of this control method in V-VAWT applications is reported. This work includes the design, construction and performance testing of a small V-VAWT with pitching blade tips. The tests showed that rotor power can be regulated with small blade tip areas, however, correlation between the measured and theoretical results was not good. Wind tunnel test were undertaken to determine the characteristics of the NACA0025 aerofoil used for the model blades. Performance predictions using this data showed better correlation between experimental and- theoretical results. This has allowed the theoretical model to be used with confidence for predicting the performance of larger V-VAWTs with partial-span pitch control. A theoretical model of the dynamic behaviour of a V-VAWT generator integrated with an electricity supply network has been developed and embodied in the computer program DYNVAWT. This program has allowed the dynamic behaviour of a 5kW sized V-VAWT to be simulated, and an active control strategy developed. The simulation studies show that active partial-span pitch control ensures the quality and reliability of the electricity supply can be maintained even when the V-VAWT is operating in turbulent wind conditions.
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Marnett, Markus [Verfasser]. "Multiobjective Numerical Design of Vertical Axis Wind Turbine Components / Markus Marnett." Aachen : Shaker, 2012. http://d-nb.info/1067735100/34.
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Courtney, M. S. "An investigation of H configuration vertical axis wind turbine dynamic instability." Thesis, City University London, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370930.
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Worasinchai, Supakit. "Small wind turbine starting behaviour." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/4436/.
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Small wind turbines that operate in low-wind environments are prone to suffer performance degradation as they often fail to accelerate to a steady, power-producing condition. The behaviour during this process is called “starting behaviour” and it is the subject of this present work. This thesis evaluates potential benefits that can be obtained from the improvement of starting behaviour, investigates, in particular, small wind turbine starting behaviour (both horizontal- and vertical-axis), and presents aerofoil performance characteristics (both steady and unsteady) needed for the analysis. All of the investigations were conducted using a new set of aerodynamic performance data of six aerofoils (NACA0012, SG6043, SD7062, DU06-W-200, S1223, and S1223B). All of the data were obtained at flow conditions that small wind turbine blades have to operate with during the startup - low Reynolds number (from 65000 to 150000), high angle of attack (through 360◦), and high reduced frequency (from 0.05 to 0.20). In order to obtain accurate aerodynamic data at high incidences, a series of CFD simulations were undertaken to illustrate effects of wall proximity and to determine test section sizes that offer minimum proximity effects. A study was carried out on the entire horizontal-axis wind turbine generation system to understand its starting characteristics and to estimate potential benefits of improved starting. Comparisons of three different blade configurations reveal that the use of mixed-aerofoil blades leads to a significant increase in starting capability. The improved starting capability effectively reduces the time that the turbine takes to reach its power-extraction period and, hence, an increase in overall energy yield. The increase can be as high as 40%. Investigations into H-Darriues turbine self-starting capability were made through the analogy between the aerofoil in Darrieus motion and flapping-wing flow mechanisms. The investigations reveal that the unsteadiness associated with the rotor is key to predicting its starting behaviour and the accurate prediction can be made when this transient aerofoil behaviour is correctly modelled. The investigations based upon the analogy also indicate that the unsteadiness can be exploited to promote the turbine ability to self-start. Aerodynamically, this exploitation is related to the rotor geometry itself.
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Eriksson, Sandra. "Direct Driven Generators for Vertical Axis Wind Turbines." Doctoral thesis, Uppsala : Acta Universitatis Uppsaliensis, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9210.
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Högberg, Lars. "Automated electric control of a vertical axis wind turbine in island operation." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-162559.
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At the Division of Electricity at Uppsala University, a wind power concept has been developed. The concept uses a vertical axis wind turbine with a direct driven generator. The turbine has fixed blades, making speed control the only way to regulate power absorption. The speed is controlled with the electric load. The turbine is not self-starting, but can be started using the generator as a motor. In this project, an unsupervised electric system with automatic control is designed and constructed. The starting point is a detailed study of the earlier developed control system. To be able to select the rating of the components, theoretical calculations are done. Simulations in MATLAB are performed to predict the behavior of the system. The resulting system is a working prototype in operation outside of Uppsala. The system starts the turbine using a new start-up strategy. Loading of the generator is controlled by primarily supplying a regular consumer with direct current and secondly dissipating additional power as heat. A circuit stopping the turbine, in case of different failures, is included in the system.
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Wang, Yuchen. "Blade Design of Vertical Axis Wind Turbine at Low Tip-speed-ratios." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524224348317784.
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Deglaire, Paul. "Analytical Aerodynamic Simulation Tools for Vertical Axis Wind Turbines." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-132073.
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Wind power is a renewable energy source that is today the fastest growing solution to reduce CO2 emissions in the electric energy mix. Upwind horizontal axis wind turbine with three blades has been the preferred technical choice for more than two decades. This horizontal axis concept is today widely leading the market. The current PhD thesis will cover an alternative type of wind turbine with straight blades and rotating along the vertical axis. A brief overview of the main differences between the horizontal and vertical axis concept has been made. However the main focus of this thesis is the aerodynamics of the wind turbine blades. Making aerodynamically efficient turbines starts with efficient blades. Making efficient blades requires a good understanding of the physical phenomena and effective simulations tools to model them. The specific aerodynamics for straight bladed vertical axis turbine flow are reviewed together with the standard aerodynamic simulations tools that have been used in the past by blade and rotor designer. A reasonably fast (regarding computer power) and accurate (regarding comparison with experimental results) simulation method was still lacking in the field prior to the current work. This thesis aims at designing such a method. Analytical methods can be used to model complex flow if the geometry is simple. Therefore, a conformal mapping method is derived to transform any set of section into a set of standard circles. Then analytical procedures are generalized to simulate moving multibody sections in the complex vertical flows and forces experienced by the blades. Finally the fast semi analytical aerodynamic algorithm boosted by fast multipole methods to handle high number of vortices is coupled with a simple structural model of the rotor to investigate potential aeroelastic instabilities. Together with these advanced simulation tools, a standard double multiple streamtube model has been developed and used to design several straight bladed rotor ranging from 2 kW to 20 kW.Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 704
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Ross, Ian Jonathan. "Wind Tunnel Blockage Corrections: An Application to Vertical-Axis Wind Turbines." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1271306622.
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Alverbäck, Adam. "LQG-control of a Vertical Axis Wind Turbine with Focus on Torsional Vibrations." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-169330.
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In this thesis it has been investigated if LQG control could be used to mitigate torsional oscillations in a variable speed, fixed pitch wind turbine. The wind turbine is a vertical axis wind turbine with a 40 m tall axis that is connected to a generator. The power extracted by the turbine is delivered to the grid via a passive rectifier and an inverter. By controlling the grid side inverter the current is controlled and hence the rotational speed can be controlled. A state space model was developed for the LQG controller. The model includes both the dynamics of the electrical system as swell as the two mass system, consisting of the turbine and the generator connected with a flexible shaft. The controller was designed to minimize a quadratic criterion that punishes both torsional oscillations, command following and input signal magnitude. Integral action was added to the controller to handle the nonlinear aerodynamic torque. The controller was compared to the existing control system that uses a PI controller to control the speed, and tested usingMATLAB Simulink. Simulations show that the LQG controller is just as good as the PI controller in controlling the speed of the turbine, and has the advantage that it can be tuned such that the occurrence of torsional oscillations is mitigated. The study also concluded that some external method of dampening torsional oscillations should be implemented to mitigate torsional oscillations in case of a grid fault or loss of PWM signal.
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Madani, Nima. "Design of a Permanent Magnet Synchronous Generator for a Vertical Axis Wind Turbine." Thesis, KTH, Elektrisk energiomvandling, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-53688.
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Different types of permanent magnet generators for wind power application have been subject of research during last two decades. In this thesis different topologies of electrical generators have been investigated for small scale vertical axis wind turbine application. A two stage induction generator is proposed as a alternative solution with respect to the cost of such a system. However, a biggest emphasis in the report has been put on the design of Permanent Magnet Synchronous Generator (PMSG) suitable for a small scale Vertical Axis Wind Turbine (VAWT)T˙ he characteristics of PMSG makes it highly compatible for variable speed Wind Energy Conversion System (WECS) without any pitch mechanism. Chapters 2 and 3 summarize a thorough literature survey on wind energy systems and corresponding electrical machines. The principles of wind aerodynamics is preceded by a review on wind turbine characteristics and challenges with emphasis on VAWT s. Further different topologies of electrical machines with focus on PMSG s including Permanent Magnet (PM) configurations, different windings and thermal behavior is presented. In chapter 4 a brief review on an alternative solution which includes an Induction Generator (IG) for fixed speed WECS is given. Next, In chapters 5, 6 and 7, a PMSG is designed and the design is verified by means of Finite Element Method (FEM) analysis and thermal modeling. Chapter 5 describes an analytical optimisation of a longitudinal, inner rotor, radial flux, surface mounted PMSG with concentrated winding and natural air cooling system. Cost of active material is chosen as the optimisation criterion. Concepts like "constraints", "requirements", "parameters" (including material, geometry and winding) and procedure of the design are described here. In chapter 6, a FEM model of the optimised machine is developed and the results are illustrated. The iron losses, calculated in this chapter are utilised in thermal analysis in chapter 7 . Thermal model developed is based on a lumped parameter circuit . It ensures the safe thermal behavior of the machine in nominal operation mode.
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Park, Kyooseon. "Optimal design of a micro vertical axis wind turbine for sustainable urban environment." Thesis, University of Huddersfield, 2013. http://eprints.hud.ac.uk/id/eprint/19032/.
Full textAbstract:
The need for sustainable energy sources becomes greater each year due to the continued depletion of fossil fuels and the resulting energy crisis. Solutions to this problem are potentially in the form of wind turbines, for sustainable urban environment, that have been receiving increased support. At present, a number of wind turbines have been developed that show significant increase in performance compared to existing technologies. From an extensive literature review, a number of key issues have been highlighted which are concerned with the design, optimisation and diagnostics of Vertical Axis Wind Turbines (VAWTs) that have been used to formulate the scope of this research. A design procedure for a vertical axis wind turbine, that features both multi-blade rotor and fixed outer stator guide vanes, has been derived, in which both rotor and stator blade profiles have been generated for a low wind speed application. In the presented work, numerical investigations have been carried out extensively to determine the optimised design of the VAWT. Sliding mesh technique has been used for the rotation of rotor blades. This new technique captures the transient flow phenomena that occur when the rotor and the stator blades interact with each other. Hence, the results predicted by CFD using this technique are much superior in accuracy. Furthermore, a detailed flow field analysis of the VAWT has highlighted large asymmetries in both pressure and flow velocity about the central axis of the VAWT in both the stationary and the rotating frames of references. Various geometric parameters associated with the design of the VAWT have been investigated over a wide range in order to analyse the effect of these parameters on the performance output of the VAWT. These geometric parameters are the blade angles, the number of blades in the VAWT and the size of the rotor/stator sections of the VAWT. It has been shown that all these parameters considerably affect the performance output of the VAWT and hence have been optimised in the present study for maximum performance output of the VAWT. One of the key elements of this study is the development of a performance prediction model of the VAWT that takes into account the effects of the aforementioned geometric parameters of the VAWT. This novel prediction model is both robust, user-friendly and has shown to predict the performance output of the VAWT with reasonable accuracy. Hence, the prediction model can be used by the designers of the VAWT. Nowadays, condition based health monitoring of mechanical systems is topic of vast research. Most of the studies in this field use experimental facilities and conventional toolboxes to handle the output data from the sensors. With the advent of advanced CFD tools, it has now become possible to use CFD as an effective tool for fault detection in VAWTs. An attempt has been presented in this study regarding condition monitoring of VAWTs for sustainable urban environment. Various faults like missing blade and slits in blade have been investigated and analysed. It has been shown that CFD can detect these faults and show the effects of these faults on local flow parameters such as pressure and velocity.
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Perera, Guruge Elmo Lakshman. "A vertical axis wind turbine generator based on the tangential wall-jet action." Thesis, University of Huddersfield, 1988. http://eprints.hud.ac.uk/id/eprint/7480/.
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Yi-ChenKuo and 郭奕甄. "The Performance Analysis of Rotor Blades for Horizontal-Axis Wind Turbine (HAWT) and Vertical-Axis Wind Turbine (VAWT)." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/50081116018964036703.
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碩士國立成功大學
航空太空工程學系碩博士班
100
This thesis employs the modified blade element momentum theory, computational simulation, and wind tunnel experiment to analyze and compare respectively the performance rotor blades used in Horizontal-Axis wind turbine (HAWT) and Vertical-Axis wind turbine (VAWT). The Blade element momentum theory is used to predict the rotor performance of HAWT and the adopted double-multiple streamtube model to calculate that of VAWT. For computational simulation, it uses the same turbulent model to simulate the rotors. Furthermore, the performance of the rotor is obtained through the experiments rotor rotation speed, output torque and current and voltage from the generator in terms of the wind speed at various tip speed ratio. It can identify the optimum operation regions of both wind turbines via experiment. Results indicate that the torque output of both wind turbines obtained has almost the same range between 0.3 to 0.4 N-m in experiment under the wind speed of 8 m/s. The maximum torque of VAWT is at TSR of 0.5 while that of HAWT is at TSR of 3.5. The maximum power of HAWT is about 30 watt, which is 6 times larger than VAWT. In addition, the power coefficient of HAWT is about 5 times larger than VAWT, which means that the HAWT has much higher ability to extract the energy in wind than the VAWT. These results are also verified by the modified BEM theory and CFD simulation.
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Babu, Harish, and Dona Maria Mathew. "A Feasibility Study and Business Model for Micro Vertical Axis Wind Turbine in Sweden." Thesis, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-44712.
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This project is a part of the master thesis for the course Energy smart innovation in the built environment at Halmstad University. This project is done to check the feasibility of VAWT on replacing traditional horizontal axis windmills, costly offshore windmills, and other renewables. As Micro VAWT are smaller, they can be placed where traditional windmills will not be. To stress the point, these can be placed in places like traffic islands and open garden areas. Lots of such projects are currently ongoing in different parts of the world. Sweden is lagging in this technology diffusion. We concluded that VAWM couldn't alone be used to replace traditional HAWTs or be enough to reach the full renewable target. They can be used in conjunction with HAWT to boost production and efficiency, and we also found other similar uses for VAWM. A business model is suggested so as for the optimal diffusion of VAWT. Our proposal of a micro VAWT of 1.8 million was able to produce 1.41TWh.We found that it was not possible to achieve with VAWT alone.
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Lan, Wei-Chen, and 藍威政. "Characteristics Of Vertical Axis Wind Turbine." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/69901264973666309305.
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碩士中華科技大學
機電光工程研究所碩士班
100
Due to their location and climate, Taiwan has a rich energy of the wind farm, if with sharp optimized power generation system is a very suitable environment for the development of wind power generation. The vertical axis wind turbine characteristics, with low start up wind speed from the direction of the impact of simple structure. Therefore, this study will be Elizabeth Vilnius wind turbine vertical axis wind turbine for the design basis. This study was to investigate the impact of different horizontal torque generating capacity and efficiency. Second set of different wind speed and the size of the different cross-sectional area of the fairing to the measurement of the parameters (voltage, current, CP and wind power) into the wind characteristics of formulas and effectiveness of the formula to calculate the wind turbine power generation system attribute parameter and comparative analysis of their advantages and disadvantages.
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Tien-HsinChao and 趙天昕. "Performance analysis and comparison between cross-axis wind turbine and vertical axis wind turbine." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/846ue5.
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碩士國立成功大學
航空太空工程學系
105
Wind energy has been considered as one of the primary renewable energy sources globally. In urban areas, due to the irregular arrangement of buildings, small scale wind turbine plays an important roles for household energy grid. In this study, a newly designed small scale wind turbine namely cross-axis wind turbine (CAWT) was examined experimentally on the power performance in a low speed, open-loop circuit wind tunnel at Reynolds numbers of Re=42900, 57100 and 71400. The results were compared to a traditional straight-bladed vertical axis wind turbine (VAWT). The performance analyses are evaluated in terms of static performance, dynamic performance, and blade force measurement. The results of static and dynamic performances indicate that CAWT has not only better starting characteristics but also higher power coefficients over VAWT. The tangential forces measurement on the horizontal blade of CAWT proves its superior power performance compared to VAWT.
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Chen, Si-Han, and 陳思翰. "Optimization of Novel Vertical-Axis Wind Turbine." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3kpkzv.
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碩士國立臺灣科技大學
機械工程系
102
This research uses ANSYS FLUENT software to analyze the new vertical-axis wind turbine in order to investigate the relationship between the flow field, force and torque. When conventional vertical-axis wind turbine blades translate wind power into thrust on the windward side, the blade of upwind side also generate resistance against the effective moment; The new vertical-axis wind turbine has fixed outer guide blades in order to make wind be imported effectively to the rotor blades on the windward to improve the positive torque. In addition, block the wind the guide blades which hits on the rotor blades, on the upwind side. Thus, the reverse torque will be declined. Finally, using Taguchi method to find the optimal experimental parameters by 9-level orthogonal arrays. Four factors, the angle of rotor blades, the number of rotor blades, the angle of fixed outer guide blades and the number of fixed outer guide blades. The optimal parameters are rotor blade angle of 90 degree, 15 rotor blades, the fixed outer guide blades angle of 48 degree and 12 fixed outer guide blades.
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KAO, KUO-CHUN, and 高國峻. "Aeroacoustic Analysis of a Vertical Axis Wind Turbine." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/41726379423056837522.
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碩士國立中央大學
機械工程學系
101
In this study, the aeroacoustic characteristics of a small vertical axis wind turbine are analyzed by using ANSYS FLUENT. The FW-H theory with a permeable surface is chosen for formulation. The pressure and the velocity on the rotating blades surface provide the monopoles and dipoles while turbulences surrounding the blades give the quadrupole effect. Then, the aeroacoustic noise due to the rotating wind turbine are investigated for different wind speeds and rotating frequencies. For a simple model of blades with or without considering the supporting tower, the numerical results show that the maximum sound pressure, due to blade rotating, usually occurs at the blade passing frequency although it is in the subsonic region. There is additional broadband noise, resulted from turbulences, near the frequency region 200Hz to 500 Hz. Actually, the broadband noise dominates the sound from a turbine. The maximum sound pressure level and its corresponding frequency usually increase with rotational frequency.
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Lee, Jun-Ting, and 李俊廷. "Magnetism Floats Applied on Vertical Axis Wind Turbine." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/42651913122977070537.
Full textAbstract:
碩士國立高雄海洋科技大學
輪機工程研究所
97
This research focuses on the functional combinations between vertical axis wind turbine and magnet disk for reducing weigh systems. Such a construction is mainly composed by the two pieces of circular magnetic discs. Through the insertion of the upper disc with a circular permanent magnetism NdFeB, the fixation of both compartments could be achieved. The ironic lower disc would then be connected with the generator, blades, and framework of the vertical axis wind turbine. According to the law of magnetic suction, a force of attraction would be generated by both upper and lower discs. It is predicted that such an application can effectively reduce required spare parts, thus decreases the ponderousness of the turbine itself. The main concerns of the article are as follows: 1. The comparison of the magnets and their force of the attraction of different models (operated under static simulation). 2. The graphic comparison of magnetic force curve under different rotational speed. 3. The comparison of the magnetic field intensity (H) and the magnetic flux density (B). The experiments will be able to get the required data of the system, under which condition it reaches the maximum stability. The data not only help minimizing the vibration, but also reduce generated friction during high speed rotation of the vertical axis wind turbine.
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CHANG, CHIA-HUI, and 張珈誨. "Performance Optimization of the Vertical-Axis Wind Turbine." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f3u9mq.
Full textAbstract:
碩士逢甲大學
航太與系統工程學系
107
Environmental problems such as global warming and extreme weather have become more and more serious. Reducing carbon emissions is the most problem that needs to be addressed at present. It is also a top priority to develop renewable energy, not only to solve the energy crisis but also to reduce the load on the earth. In recent years, green energy wind energy is the most growing energy source, so wind power generation is also receiving more and more attention. The purpose of this study is to use the CFX module of ANSYS software to develop the wind turbine’s flow-field simulation, and then correctly predict the power generation efficiency of the wind turbine. In this study, two different configurations of the Lift type of the vertical axis wind turbine (VAWT) is used as a model for simulation analysis. The chord length, the blade’s scale and the number of blade torsion turns are used as parameters to test, and then divided into four different speeds and four different wind speeds. Perform flow-field Simulation to analyze the optimal torque from the speed and wind speed and obtain the best power generation. This analysis is used to shorten the development time, find the optimal combination of wind turbine, and further build a good performance vertical axis wind turbine (VAWT) to generate electricity.
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Yu, Luo Sheng, and 羅勝禹. "Development of Small Vertical Axis Wind Turbine Blade." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/44296369380828706717.
Full textAbstract:
碩士建國科技大學
機械工程系暨製造科技研究所
101
A small vertical axis wind turbine (SVAWT) with lift-type and drag-type blades were designed and tested in this paper. In order to improve the performance of the SVAWT with low start up wind speed, the struts connecting lift-type blades and rotating axis were designed as drag-type blades. The cross section of lift-type blades using in the SVAWT was NACA0018 for maintaining the rotating speed under higher wind speed. The parts of the SVAWT including blades and struts were designed by computer-aided design software and manufactured with the aid of computer-aided manufacturing, rapid prototyping and rapid tooling. The SVAWT was tested in a wind tunnel with the wind speed ranging from 2 to 7 m/sec. The test results containing rotating speed and torque were recorded to evaluate the performance of the SVAWT. The results showed that the drag-type blade could start up the SVAWT wind low speed, but would reduce the rotating speed under higher wind speed.
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Chen, Hung-Ju, and 陳虹汝. "3D Simulation of a Vertical-Axis Wind Turbine." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/82161970916439943950.
Full textAbstract:
碩士國立交通大學
機械工程學系
100
A vertical-axis wind turbine which combines the merits of the lift type and drag type wind turbines is studied in this project. It consist of three S-type and two airfoil-type turbine blades. Several stages of these turbine blades can be stacked together to achieve better performance. The aerodynamic characteristics and performance are investigated by using computational fluid dynamic. The numerical scheme is based on the finite volume method. The moving mesh technique is adopted to tackle the rotation of the turbine wheel.With use of the RNG model to characterize turbulence, unsteady calculations are undertaken. Experiments are also conducted to assess the accuracy of the numerical simulation. Two-dimensional and three-dimensional, unsteady simulations are conducted. It is shown that the resulting moment coefficient becomes a linearly decreasing function of the tip speed ratio and the power coefficient is a quadratic function of the tip speed ratio. Comparison with experimental measurements for a one-stage wind turbine indicates that good agreement is obtained by the 3-D unsteady simulation. However, the torques and powers are over-predicted by the 2-D unsteady calculations. It can be detected from the results that after the flow passing the wind turbine, a periodic shedding vortex is formed in 2-D calculations while a relativity steady flow is observed in 3-D calculations. This implies that the flows beyond the upper and lower sides of the wind turbine have an effect of stabilizing the flow in the near wake of the turbine. This 3-D effect cannot be accounted for in 2-D calculations. Comparing with the single-stage wind turbine, only slightly higher power performance can be obtained by stacking several stages of turbines together. However, the variation of the torque with respect to time becomes smoother as the number of stage increase. This character helps stabilize operation of the wind turbine.
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Lin, Chien-Yao, and 林健耀. "Numerical studies of the vertical axis wind turbine." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/61616991835331149572.
Full textAbstract:
碩士國立屏東科技大學
車輛工程系所
96
The development and application of wind power for renewable energy has been grown vigorously in recent years. With the characteristics of operating in all directions, simple structure and low rotating noise, the vertical axis wind turbine is also used in the production of electrical power. In this study, the different conditions included five kinds of rotating speeds and three kinds of wind speeds are used to simulate and analyze the flow field which caused by the vertical axis wind turbine. The SIMPLE finite volume method, the k-ε model and sliding mesh model are employed to solve and compare the complex flow field and the torque in each case. The purpose is to provide the fundamental flow phenomena caused by the rotating vertical fan and the design concept of vertical axial wind turbine in the future. In the results, we can observe that while the rotor rotates to the region of upper flow, the separation bubble on the surface of rotor disappears and causes the difference of pressure increased between top and bottom surfaces of rotor. Meanwhile, the torque will be heightened while the difference of pressure increased. The rotor’s rotating speed and torque also increased while the inlet velocity of flow speeded. However, the increased proportion of speed between rotating rotor and inlet flow is not entirely linear.
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Cai, Yao-Ting, and 蔡耀庭. "The Blade Analysis of Small Vertical Axis Wind Turbine." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/80427664688503329326.
Full textAbstract:
碩士明道大學
光電暨能源工程學系碩士班
100
To address the lack of energy and global warming problem, people should develop clean and renewable energy resources. Renewable energy development is the world trends and is also the energy policy of Taiwan. The record shows that wind power generation worldwide has expanded with an annual growth rate of 25 percent since 1990. In recent years, the worldwide wind turbine installation capacity has dramatically increased. The global wind turbine market is expected to continue growing rapidly and stably, making wind turbines an increasingly important energy source. Since 2007, MingDao University has set up a 2kW VAWT prototype that is test verified to have excellent performance. In 2010, to reach the goal of reducing carbon emissions and saving energy, the Ministry of Economic Affairs granted us a research project to develop the 4kW VAWT to provide the electrical power for small families or public power use in local communities. Emerging markets need small sized VAWT (vertical-axis wind turbine) for residential energy supplement. MingDao university wind power R&D team has developed a 4kW VAWT system is response to this need. The development items include innovative blades, generator, power control and mast design. The newly developped 4kW VAWT system demonstrates superior performance. The average VAWT efficiency is 0.24 and the average Cp is 0.30. The preliminary results showed this approach has potential for future applications. Keywords : VAWT, Renewable Energy, Innovative Blades
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Hong, J. S., and 洪雋翔. "Stress Analysis of Small Vertical Axis Wind Turbine Blades." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/04293726243858341649.
Full textAbstract:
碩士建國科技大學
機械工程系暨製造科技研究所
100
A compact aerodynamics model combined computer-aided engineering analysis software was used to investigate the stresses of small scale vertical wind turbine blades subjected to the aerodynamics loads in this paper. The airfoil types used in the paper are NACA0012, NACA0015 and NACA0018 with the rotational speed 150 rpm and wind velocity 4 m/s. The model used to decide the aerodynamics loads on the blades was formulated with the blade element momentum method (BEM) and multiple stream-tubes method. The relations between lift-coefficient/drag-coefficient and angle of attack from X-FOIL are compared to experimental data to validate the data. Although the maximal errors are up to 50% in some ranges of Reynolds’ number and angle of attack, the comparison data shows that the two data are agree with well when Reynolds’ number is greater than 1.6 x 105 and the angle of attack less than 10°. The angle of attack, lift coefficient and drag coefficient are varied with the angles of rotation of blades, which change the stresses distribution of the blades. The results show that the stresses of blades varied with the angles of rotation of blades. The maximal von Mises stresses occurs when the blade chord is almost parallel to the direction of wind.
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Chang, I.-Chieh, and 張奕傑. "Vibration Analysis of Rotating Vertical Axis Wind Turbine Blades." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26983033782497948789.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
99
Wind power is the most potential source of renewable energy. There are two categories of modern wind turbines, namely horizontal axis wind turbines (HAWT) and vertical axis wind turbines (VAWT). Vertical axis wind turbines have the major benefit of operation that is independent of the wind direction. Other benefits include easier installation and lower noise radiation than the horizontal axis wind turbines. Therefore they have great potential for applications in the urban area. Nevertheless, higher efficiency is offered by a horizontal wind turbine as it has blades in perpendicular to direction of wind and hence receives more power for rotation. To ensure that the blades operate effectively, it is important that that their structure is dynamically safe when in rotation. There has been a growing interest in the investigation of free vibration characteristics of rotating beams because the topic plays an important role in the design of shafts, turbine blades, propellers and many other rotating structures. In this present paper, we use Hamilton’s principal to derive the dynamic governing equations for the rotational slender blade. We especially take rotational velocity which is a very important parameter when rotating into consideration. Theoretical natural frequencies and mode shapes for some illustrative examples are calculated and compared with the simulation of ANSYS Workbench. These results are discussed and compared with published ones, and we can predict the first few lower natural frequencies quite accurately. Vertical axis wind turbine is verified that the theoretical model can provide mechanical insight into the design of the blades. The vertical axis wind turbine blades are flexible, highly dynamic structure, with many natural modes of vibration that must be carefully analyzed to ensure the blades are dynamically stable under all operating conditions.