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Journal articles on the topic "Diffuser augmented wind turbine"
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Chhetri, Roshan Kumar, Dilip Bhattarai Upadhyay, and Nirajan Ghimire. "Comparative Analysis of Diffusers for Micro Wind Turbine." Nepal Journal of Science and Technology 20, no. 2 (2021): 103–12. http://dx.doi.org/10.3126/njst.v20i2.45796.
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With the increase in demand for clean energy, a micro wind turbine would be the best option for remote and urban residential areas. Installing wind turbines is not feasible in most land areas due to low or inadequate wind speed. The energy generated by the wind turbine is directly proportional to the cube of wind velocity. So, if we manage to increase wind speed slightly, it would increase energy significantly. One approach to solving problems in areas with low wind speed is using Diffuser Augmented Wind Turbine (DAWT). In DAWT, the turbine blades are typically surrounded by a duct which increases the cross-sectional area in the stream-wise direction. Since a diffuser encloses the wind turbine, the pressure behind the turbine will drop, which results in an increasing wind velocity. Different types of diffusers have been introduced to increase wind velocity. The main aim of the research is to perform a comparative analysis of four different types of diffusers to increase the power output of wind turbines. The CFD simulation of Plain Diffuser, Plain Diffuser with Inlet Shroud, Flanged Diffuser, and Flanged Diffuser with Inlet Shroud is performed to determine the maximum velocity each diffuser produced. With the solution from the simulation, a comparative analysis of each diffuser is conducted, and the results are further verified with the previous studies on DWAT. And Flanged Diffuser is found to be optimum with an increase in power generation up to 3.6 times compared to a bare wind turbine.
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Ahmed M. Elsayed. "Design Optimization of Diffuser Augmented Wind Turbine." CFD Letters 13, no. 8 (2021): 45–59. http://dx.doi.org/10.37934/cfdl.13.8.4559.
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The wind turbine power decreases at low wind speed. A flanged diffuser plays a role of a device for collecting and accelerating the approaching wind, and thus the optimization of the diffuser shape presents an important way to enhance the wind turbine power. In this work, a numerical parametric study was conducted on the diffuser to obtain the initial optimum form of flanged diffuser. Then, the Simplex algorithm is used to obtain the optimal diffuser shape starting from the obtained initial shape. Finally, the obtained optimum diffuser shape is used with conventional wind turbine blade. The diffuser shape is defined by four variables: open angle, flange height, centerbody length, and flange angle. The numerical simulation of flanged diffuser is carried out using the “CFDRC package. The results indicated that, the optimum diffuser shape can be obtained using simplex algorithm which maximizes the entrance average velocity to reach 1.77 times wind speed. The power augmented by a factor about 2.76:5.26 of a selected small wind turbine using the obtained diffuser shape compared to that without diffuser.
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Qashidi Putra, Fariz, Dani Rifai, Kutut Suryopratomo, and Rachmawan Budiarto. "Multilevel Diffuser Augmented for Horizontal Axis Wind Turbine." E3S Web of Conferences 42 (2018): 01001. http://dx.doi.org/10.1051/e3sconf/20184201001.
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Indonesia is an area with the low and fluctuating wind speed. Therefore, the implementation of the wind turbine to generate electricity become ineffective and economically unprofitable. Diffuser Augmented Wind Turbine (DAWT) is the augmentation technology in wind turbine which could increase wind speed flow that arrives on the turbine blade. The working principle of the diffuser is to create a difference in pressure inside and outside the diffuser. The pressure inside the diffuser is lower than the pressure outside so that the wind will be accelerated into the diffuser and wind speed will dramatically increase at the inlet of the diffuser. This study will be presenting a modified design of diffuser augmented wind turbine (DAWT) by designing multilevel diffuser with additional inlet curvature and flange. This research aims to evaluate the amplification of flow velocity profile around the diffuser that has been engineered. The numerical study is performed using computational fluid dynamic (CFD) to obtain the highest ratio of speed increment. The verification of numerical initial condition is validated by comparing the result of validation with experimental data available in the literature. The result shows that a ratio of increase in speed is 2.08 times higher than conventional wind turbine over 4 m/s inlet velocity. In the equation of a wind power output, the wind speed is proportional to the cubic power of its wind power output. Therefore, the utilization of dual-stage diffuser device in wind turbine would give significant increment on the power output of wind turbine.
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Maw, Yu Yu, and Min Thaw Tun. "SENSITIVITY ANALYSIS OF ANGLE, LENGTH AND BRIM HEIGHT OF THE DIFFUSER FOR THE SMALL DIFFUSER AUGMENTED WIND TURBIN." ASEAN Engineering Journal 11, no. 4 (2021): 280–91. http://dx.doi.org/10.11113/aej.v11.18102.
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This paper presents the performance of the diffuser augmented wind turbine (DAWT) with the various diffuser shapes using the numerical investigations. DAWT is also a type of wind turbine and the diffuser shapes, the nozzle shapes and the cylindrical shapes are commonly inserted around the horizontal axis wind turbine (HAWT) to become the more efficient wind turbine. The aim of this study is to find the more efficient design of the diffuser for the horizontal axis wind turbine using the numerical investigations. In this research, the converging and diverging diffuser shape is inserted and the airfoil design is calculated by using the Blade Elementary Momentum Theory. The airfoil type NACA 4412 is chosen because it is suitable for the low wind speed area and easy to produce. The turbulent model k-ω is combined with the Navier Stoke equation to solve the 3-dimensional steady flow simulation of the diffuser augmented wind turbine using the Computational Fluid Dynamics (CFD) simulations. The numerical investigation is used to compare and predict the power coefficient of the DAWT with various shapes. The baseline design of the diffuser (L = 170 mm, H = 57 mm and α = 11̊) is firstly investigated. To predict the power coefficient of the various diffuser shapes, the range of the length of the diffuser is (L/D = 0.5 to 1.5), the range of the brim height of the diffuser (H/D = 0.1 to 0.35) and the range of the angle of the diffuser (α = 5̊ to 15̊ ) are also investigated. The parameters of the diffuser shapes are assigned by using the Central Composite Design Face Centered Method. The response surface method is also used to predict the most efficient diffuser design. The performance of the horizontal axis wind turbine, that of the diffuser augmented wind turbine and that of the diffuser augmented wind turbine with various shapes of diffuser are compared. The performance of new diffuser augmented wind turbine (IND_009) is 50% and 55% higher than the baseline diffuser augmented wind turbine and the horizontal axis wind turbine at rated velocity. The flow visualization of the HAWT, DAWTs are also discussed.
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Barbosa, D. L. M., D. A. T. D. R. Vaz, J. R. P. Vaz, et al. "A PROPOSED MATHEMATICAL MODEL FOR THE VELOCITY PROFILE INTERNALLY TO A CONICAL DIFFUSER." Revista de Engenharia Térmica 12, no. 2 (2013): 69. http://dx.doi.org/10.5380/reterm.v12i2.62050.
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The use of diffusers around of the horizontal-axis wind turbines have been widely studied, since the diffuser provides an improvement in the turbine power coefficient. These diffusers are often called Diffuser Augmented Wind Turbines (DAWT’s). The DAWT’s have the feature to make efficiency exceeding the Betz limit (maximum energy flow extracted = 59.26%), due to the increasing of the internal mass flow by influence of the diffuser presence. Thus, the present work proposed a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The model results were compared with experimental data and showed good agreement.
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Irawan, Yosua Heru, and M. Agung Bramantya. "SIMULASI NUMERIK PADA DIFFUSER AUGMENTED WIND TURBINES DENGAN ROTOR GANDA KONTRA ROTASI." KURVATEK 3, no. 1 (2018): 13–20. http://dx.doi.org/10.33579/krvtk.v3i1.574.
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Wind energy is one form of renewable energy in Indonesia and its potential is very large to be utilized. Wind energy can be converted into electrical energy using wind turbines. Horizontal axis wind turbine will be the subject of this study, where the wind turbine model will be given additional diffuser. In addition, this wind turbine model will also be developed from a single rotor wind turbine into a double rotor wind turbine with opposite rotation direction or counter rotation. This research uses numerical simulation method using ANSYS Fluent software to know wind turbine performance. Simulations were performed at wind speeds of 3 m/s, with the ratio of the length and diameter of the inlet diffuser 0.5; 1; 1.5; 2; and 2.5. Based on the simulation results, it can be seen that the greater the ratio of inlet length and diameter, the mechanical power generated by the wind turbine rotor is greater. Double rotor wind turbine with a length ratio and 2.5 inlet diameter produces the highest performance on the front rotor and rotor rear. The greater the ratio of the length and diameter of the inlet, the mechanical power generated by the front rotor and the rotor inside the diffuser also increases.
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Kosasih, Bu Yung, and S. A. Jafari. "High-Efficiency Shrouded Micro Wind Turbine for Urban-Built Environment." Applied Mechanics and Materials 493 (January 2014): 294–99. http://dx.doi.org/10.4028/www.scientific.net/amm.493.294.
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Shrouding (diffuser augmented) horizontal axis micro-wind turbine has been shown to be an effective ways to potentially increase the power output of micro wind turbine for applications in built environments. It is well understood that the degree of the performance enhancement depends on several factors including the diffuser shape and geometries, blade airfoils, and the wind condition at the turbine site. The effect of diffuser shape and geometries is reported in this paper. Computational fluid dynamic (CFD) simulations of a small wind turbine with a simple frustum diffuser shrouding have been carried out. The diffuser has been modeled with different shapes with the aim to understand the effect of length and area ratio on power augmentation phenomenon. The simulations provide some parameterized figures which present method to determine the beneficial range of frustum diffuser geometries for diffuser shrouded horizontal axis wind turbines.
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Ilhan, Akin, Besir Sahin, and Mehmet Bilgili. "A review: diffuser augmented wind turbine technologies." International Journal of Green Energy 19, no. 1 (2021): 1–27. http://dx.doi.org/10.1080/15435075.2021.1914628.
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NAGAI, Minoru, and Kunio IRABU. "Momentum theory of diffuser augmented wind turbine." Transactions of the Japan Society of Mechanical Engineers Series B 53, no. 489 (1987): 1543–47. http://dx.doi.org/10.1299/kikaib.53.1543.
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Hjort, Søren, and Helgi Larsen. "A Multi-Element Diffuser Augmented Wind Turbine." Energies 7, no. 5 (2014): 3256–81. http://dx.doi.org/10.3390/en7053256.
Full textDissertations / Theses on the topic "Diffuser augmented wind turbine"
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Masukume, Peace-Maker. "Electrical power output estimation model for a conical diffuser augmented wind turbine." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/1517.
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Energy is integral to the quality of life of any society. However, meeting the demand for energy sustainably is the main challenge facing humanity. In general, non-renewable energy resources are used to supply the ever increasing energy demand. However, the extraction and processing of these resources is accompanied by the production of wastes which are a health hazard and impact negatively on climate change. Considering the finite nature of non-renewable sources, the environmental concerns which are associated with their usage and ensuring energy security, renewable energy sources have been brought in the energy supply chain. Wind energy is one of the renewable energy sources which has been supplying electrical energy to the ever increasing energy demand of humanity. Wind energy technology is a mature technology which over and above the bare (conventional) wind turbine technology has seen the development of duct augmented wind turbines. Ducts are used to encase wind turbine rotors to augment the power output of wind turbines especially in low wind speed areas. Though the technology has been under study for decades now, research indicates that there is no known model to estimate the power output of a diffuser augmented wind turbine. This thesis presents the development of the conical Diffuser Augmented Wind Turbine (DAWT) power output estimation model and its validation.
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Kishore, Ravi Anant. "Small-scale Wind Energy Portable Turbine (SWEPT)." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23099.
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Large Scale Wind Turbines (LSWTs) have been extensively examined for decades but very few studies have been conducted on the small scale wind turbines (SSWTs) especially for the applications near ground level where wind speed is of order of few meters per second. This study provides the first systematic effort towards design and development of SSWTs (rotor diameter<50 cm) targeted to operate at low wind speeds (<5 m/s). An inverse design and optimization tool based on Blade Element Momentum theory is proposed. The utility and efficacy of the tool was validated by demonstrating a 40 cm diameter small-scale wind energy portable turbine (SWEPT) operating in very low wind speed range of 1 m/s-5 m/s with extremely high power coefficient. In comparison to the published literature, SWEPT is one of the most efficient wind turbines at the small scale and very low wind speeds with the power coefficient of 32% and overall efficiency of 21% at its rated wind speed of 4.0 m/s. It has very low cut-in speed of 1.7 m/s. Wind tunnel experiments revealed that SWEPT has rated power output of 1 W at 4.0 m/s, and it is capable of producing power output up to 9.3 W at wind speed of 10 m/s. The study was further extended to develop a piezoelectric wind turbine which operates below 2.0 m/s wind speed. The piezoelectric wind turbine of overall dimension of 100mm x 78mm x 65mm is capable of producing peak electric power of about 450 microwatt at the rated wind speed of 1.9 m/s.<br>Master of Science
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Lipian, Michal. "Modèle hybride pour simuler l’écoulement à travers un birotor éolien caréné et sa validation expérimentale." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0073/document.
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La thèse résume la recherche sur le fonctionnement et l’écoulement autour d’une éolienne caréné à deux rotors. Le placement d’une turbine à l’entrée d’un canal divergent permet d’augmenter le débit massique à travers le rotor. Afin de mieux tirer parti de l’augmentation de la vitesse du vent à l’entrée du diffuseur, il a été décidé d’examiner la possibilité de placer un deuxième rotor, tournant dans le sens opposé, dans cette zone.L'étude menée combinait plusieurs voies de recherche différentes, y compris les méthodes de la mécanique des fluides numérique (CFD) et des études expérimentales. Cela a permis de mieux comprendre la nature de l'écoulement et du fonctionnement d'une éolienne à deux rotors. Des recherches expérimentales ont été menées dans la soufflerie de l’Institut de Turbomachinerie de l’Ecole Polytechnique de Lodz (Pologne). Une série de mesures de systèmes d'éoliennes divers, avec et sans carénage, à un et deux rotors, a été réalisée. Les résultats recueillis ont permis de confirmer que le carénage pouvait augmenter considérablement (même deux fois) l'efficacité du rotor. Cependant, les forces aérodynamiques et la vitesse de rotation augmentent également. Cet inconvénient peut être partiellement résolu en utilisant un deuxième rotor et en répartissant les charges aérodynamiques sur deux étages de turbine.Une partie importante de l'étude était les simulations numériques. Ils ont permis de préciser la nature et les paramètres de l'écoulement et d'estimer leur impact sur les performances de l'éolienne. Deux modèles numériques différents ont été développés:• Modèle rotor complet (anglais : Fully-resolved Rotor Model, FRM): modèle URANS dans ANSYS CFX, basé sur la discrétisation de la géométrie complète du rotor; ce modèle a été utilisé pour l'analyse de l’écoulement,• Modèle hybride CFD-BET (théorie de l’élément de pâle): modèle RANS dans ANSYS Fluent, dans lequel le rotor est représenté par les termes source dans les équations de Navier-Stokes, déterminés par un code interne; ce modèle a été utilisé pour évaluer les performances de différentes configurations d'éoliennes.Au cours de la recherche, une correction empirique interne de la perte d’extrémité de la pâle (anglais : tip loss correction) a été proposée, en tenant compte de l’influence du diffuseur. L’étude réalisée a permis d’observer, entre autres, que le déplacement du rotor en aval vers la sortie du diffuseur pouvait entraîner une réduction de la vitesse du vent à travers le rotor en amont, placé à l’entrée du diffuseur, et une diminution de la puissance globale du système<br>Doctoral dissertation summarizes the research on the functioning and flow around a two-stage, shrouded wind turbine. Placing the turbine at the inlet of a diverging channel allows to increase the mass flow rate of the flow through the rotor. To better take advantage of the increase in wind speed at the diffuser inlet, it was decided to examine the possibility of placing a second rotor in this area, with the opposite direction of rotation.The conducted study combined several different research paths, including Computational Fluid Dynamics (CFD) methods and experimental studies. This allowed for a more refined understanding of the nature of the flow and operation of a wind turbine with two rotors. Experimental research was carried out in the IMP TUL wind tunnel. A series of measurements of various turbine systems with and without shroud, with single- and double-rotor wind turbine were made. The collected results allowed to confirm that the shrouding can significantly (even twice) increase the efficiency of the rotor. However, aerodynamic forces and rotational speed also increase. This disadvantage can be partially addressed by using a second rotor and distributing aerodynamic loads to two turbine stages.An important part of the study were numerical simulations. They allowed to specify in more detail the nature and parameters of the flow and to estimate their impact on the performance of the wind turbine. Two different numerical models were developed:• Fully-resolved Rotor Model: URANS model in ANSYS CFX, based on discretising the entire geometry of the rotor, used for the flow analysis,• Hybrid model CFD-BET (Blade-Element Theory): RANS model in ANSYS Fluent, in which the rotor is represented by source terms in the Navier-Stokes equations, determined by an in-house code; the model was used to evaluate the performance of different wind turbine configurations.In the course of the research an in-house, empirical tip loss correction was proposed, taking into account the influence of the diffuser. The performed study permitted to observe, among others, that moving the rear rotor towards the outlet of the diffuser may result in a reduction of the wind speed through the front rotor, placed at the inlet to the diffuser, and a decrease in the overall system power
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Samal, Nihar Ranjan. "A wind tunnel facility for the evaluation of a land-based gas turbine diffuser-collector." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76931.
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A subsonic wind tunnel facility was built and tested as part of a base line test investigating flow within a diffuser-collector. Facility controls allowed the quarter scale model to match both Reynolds number and Mach number. Mass averaged conditions at the diffuser inlet during testing were determined as 1.939 ? 106 for Reynolds number based upon diffuser inlet hydraulic diameter, and 0.418 for Mach number. A flow conditioning section prior to test section contained several interchangeable sections. Flow conditioning components were used to create flow characteristic of that leaving the last stage of a land-based gas turbine. The diffuser-collector subsystem was evaluated through the use of wall static pressure measurements, a variety of probe traverse measurements, and Stereo-PIV. Flow within the collector and diffuser were determined to be heavily dependent upon the collector geometry. PIV measurements showed the development of two large counter rotating vortices within the collector. Each symmetric vortex grew and shifted according to the collector geometry while creating complex regions of flow. Pressure recovery within the diffuser was in range of 0.47 to 0.78, and would drop to 0.52 at the collector exit. The drop in pressure recovery was presumed to be a combination of inefficient diffusion in the collector and losses due to the vortices. The baseline test was found to be successful in terms of facility design, and determining the critical flow phenomena. Further testing and experimentation are necessary to evaluate specific details of the collector geometry's effect upon the pressure recovery and flow development.<br>Master of Science
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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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Nobile, Rosario. "A computational fluid dynamics investigation of a vertical axis augmented wind turbine designed for the built environment." Thesis, University of Reading, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.631700.
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In recent years, there has been an increasing interest in vertical axis wind turbines (VA WTs); as they show a number of benefits when installed in the built environment. Nevertheless, VAWTs still suffer from: complex aerodynamics; dynamic stall and hence lower efficiency. Additionally, when they are integrated in the built environment the challenges are low/zero starting torque, noise and vibrations, visual impact and blade safety. In response to these needs, a vertical axis augmented wind turbine (A WT) has been developed, which is composed of a stator and a rotor. In this thesis, the aerodynamics of the vertical axis augmented wind turbine (A WT) was examined by employing a Computational Fluid Dynamics (CFD) tool. The main focus was on the 2D and 3D simulations of the vertical axis augmented wind turbine (A WT). In the 2D investigation, an open rotor was analysed in order to select the most appropriate mesh, turbulence model, and timestep. Successively, the rotor was combined with a stator and the results compared to the open rotor. The development of dynamic stall in both open and augmented rotors was also examined. The CFD results of the open rotor were validated using experimental data. In the 3D stator, the focus was to understand how the stator blades, the diameter and the conical surfaces could affect the flow. In the 3D open and augmented rotors, the results were compared to the 2D cases in order to evaluate similarities and dissimilarities. The 2D investigation has shown that the forces generated on the blades of an open rotor were dependent on the mesh resolution and turbulence model selected, while the timestep had small impact. The introduction of an augmenter has the potential to increase the power coefficient by 1.35 times when compared to the open rotor. However, the stator blade and conical surface orientation were found to affect the performance of the A WT, while changing the rotor blade orientation had small impact. The generation of dynamic stall was detected at low tip speed ratios (TSRs), but the turbulence model could affect its formation. The CFD results of the open rotor were found to be in good agreement with experimental data. In the 3D investigation, the stator was found to guide and accelerate the flow, but the orientation of both conical surface and stator blade play an important role. The 3D simulations, related to open and augmented rotor, were found to have similarities and dissimilarities when compared to the 2D. This research has developed a modelling technique, which could help with the further development of the AWT.
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Ximenes, Fernando Silveira. "Design de difusor aerodinâmico compacto para uma turbina eólica de pequena escala." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/182436.
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Este trabalho tem como proposta desenvolver um difusor aerodinâmico compacto para uma turbina eólica de pequena escala, objetivando alcançar um melhor start rotacional (menor torque de partida para rotacionar) em baixas velocidades de vento. Um difusor é uma estrutura em forma de aro envolta ao rotor da turbina eólica, sua função é amplificar a captação e aceleração do vento, explorando os efeitos aerodinâmicos das zonas de vórtices de baixa pressão na saída do difusor. O estudo concentrar-se-á na manipulação da geometria dos difusores, analisando como seu design impacta no seu comportamento aerodinâmico impacta na capacidade do difusor equacionar as zonas de alta e baixa pressão ao longo de sua estrutura, essa relação é determinante para o efeito aerodinâmico que acelera o escoamento de ar, resultando em um start rotacional em baixas velocidade de vento. O ponto de partida para este trabalho são os estudos desenvolvidos por Ohya et al. (2010) sobre difusores compactos-flangeados (compact-type brimmed diffuser) para turbinas eólicas, denominado Wind-lens Technology. Para alcançar os objetivos, esta pesquisa vai utilizar simulações por CFD com software de túnel de vento virtual e ensaios experimentais em túnel de vento físico para avaliar o comportamento dinâmico (turbina + difusor). Foram desenvolvidas dezenove geometrias a partir de uma área construtiva padronizada para o design de difusores. Desenvolveu-se também, a partir dos resultados encontrados, um MFI (microseparador de fluxo interno), que consiste em uma estrutura adicional com função de potencializar as zonas de vórtices (baixa pressão) no plano de saída do escoamento de ar dos difusores. Os resultados mostraram que a manipulação da geometria do difusor produziu resultados promissores em comparação com o modelo de referência, alcançando em algumas geometrias de difusores um melhor start rotacional. O MFI mostrou-se eficaz para potencializar as zonas de baixa pressão e melhorou o start rotacional. Ao final, definiu-se dois modelos de difusores e suas respectivas versões com MFI como as melhores opções para o start rotacional.<br>This work aims to develop a compact wind turbine for a turbine and a small scale, aiming at a better rotational start at low wind speeds (lower starting torque to rotate). A diffuser is a rim-shaped structure wrapped around the wind turbine rotor, its function is to amplify the wind uptake and acceleration, exploiting the aerodynamic effects of the low-pressure vortex zones at the diffuser outlet. The study will focus on the manipulation of the diffuser geometry, analyzing how its design impacts on its aerodynamic behavior, especially on the diffuser's ability to equate the high and low pressure zones along its structure, this relation is decisive for the aerodynamic effect that accelerates the air flow, resulting in a rotational start at low wind speeds. The basis for this work are studies developed by Ohya et al. (2010) on compact-flanged diffusers for wind turbines, called Wind-lens Technology. To achieve the objectives, this research will use CFD simulations with virtual wind tunnel software and experimental tests in physical wind tunnel to evaluate the dynamic behavior (turbine + diffuser). Nineteen geometries were developed from a standardized design area for the design of diffusers. An MFI (internal flow microseparator) has also been developed, which is an additional structure whose function is to potentiate the low pressure zones of the diffusers. The results showed that the manipulation of the diffuser geometry produced promising results in comparison to the reference model, reaching in some conditions superior results in RPM and initial start. The MFI proved to be effective in boosting the low pressure zones and improved the initial start. At the end, two models of diffusers and their respective versions with MFI were defined as the best options for the initial start.
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Khamlaj, Tariq A. "Analysis and Optimization of Shrouded Horizontal Axis Wind Turbines." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1543845571758119.
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Phillips, Derek Grant. "An investigation on diffuser augmented wind turbine design." 2003. http://hdl.handle.net/2292/1940.
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Diffuser Augmented Wind Turbines (DAWTs) are one of many concepts to have been proposed to reduce the cost of renewable energy. As the most commercially viable, they have been the focus of numerous theoretical, computational, and experimental investigations. Although intimated in these studies to be able to augment the power output of a wind turbine, the extent of this power increase, or augmentation, the factors influencing DAWT performance, the optimal geometric form and their economical benefit remained unanswered. It is these issues that have been addressed in this investigation. In reviewing historic investigations on DAWTs it has been identified that excessive wind tunnel blockage, inappropriate measurement technique, varied definitions of augmentation, and the inclusion of predicted performance based on incorrect assumptions have in general led to the overstatement of DAWT performance in those studies. In reassessing the performance of the most advanced of those DAWT designs, Grumman's DAWT 45, it has been calculated that the actual performance figures for the 2.62 exit-area-ratio and 0.488 length-to-diameter ratio DAWT were an available augmentation of 2.02, a shaft augmentation of 0.64 and a diffuser efficiency of 56%. By contrast, the development of the Mo multi-slotted DAWT in this investigation has yielded a design whose shaft augmentation of 1.38 was achieved by a diffuser with exit-area-ratio of only 2.22 and overall length-to-diameter ratio of 0.35. Such performance improvement has been obtained by gaining both an understanding of the flow characteristics of DAWTs and the geometric influences. More specifically it has been shown that: the velocity across the blade-plane is greater than the free-stream velocity and increases towards the rotor periphery; that the rotor thrust or disc loading impacts upon diffuser performance by altering the flow behaviour through it; and that DAWTs are able to maintain an exit pressure coefficient more negative than that attainable by a conventional bare turbine. The net result is that DAWTs encourage a greater overall mass-flow as well as extract more energy per unit of mass-flow passing through the blade-plane than a conventional bare turbine. The major drivers of DAWT performance have been shown to be the ability of the design to maximise diffuser efficiency and produce the most sub-atmospheric exit pressure possible. Parametric investigation of the various DAWT geometric components has shown peak performance to be obtained when: the external flow is directed radially outward by maximising the included angle of the external surface in conjunction with a radially orientated exit flap; by applying boundary-layer control to a trumpet shaped diffuser via a pressurised cavity within the double-skin design of the multi-slotted DAWT; having an exit-area-ratio of the order of 2.22; and by employing an inlet contraction with inlet-area-ratio matched to the mass-flow passing through the DAWT under peak operating conditions. To translate the available augmentation into shaft power a modified blade element method has been developed using an empirically-derived axial velocity equation. The resulting blade designs whose efficiencies reached 77%, twice those of Grumman, highlight the accuracy of the modified blade element method in calculating the flow conditions at the blade-plane of the multi-slotted DAWT. It was also noted that the rotor efficiencies remain below 'best practice' and therefore offer the potential for further increases in shaft augmentation. However, in order to achieve such gains, a number of limitations present in the current method must be addressed. In assessing the likely commercial suitability of the multi-slotted DAWT a number of real-world influences have been examined. Shown to have little if any effect on DAWT performance were Reynolds number, ground proximity and wind shear. Turbulence in the onset flow on the other hand had the beneficial effect of reducing separation within the diffuser. Finally, DAWT performance was assessed under yaw misalignment where it was shown that the multi-slotted DAWT performed favourably in comparison to that associated with a conventional bare turbine. The major drawback identified in the DAWT concept by this investigation was its drag loading and the fact that drag and augmentation were interdependent. The result is that the cost of a conventional DAWT is dictated by the necessity to withstand an extreme wind event despite the fact that augmentation is only required up to the rated wind speed. The overall conclusion drawn was that in order to optimise a DAWT design economically, and therefore make the DAWT concept a commercial reality, a creative solution that minimises drag under an extreme wind event would be required.
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Maia, Lino André Bala. "Experimental and numerical study of a diffuser augmented wind turbine - DAWT." Master's thesis, 2014. http://hdl.handle.net/10198/11600.
Full textAbstract:
The effect of concentrator-diffuser (C-D) of a shrouded wind turbine was studied. The
main objective involved assessing the increment that this device induces in productivity
of small wind turbines. Also the aerodynamic performance of two scaled blade models
were studied in terms of drag and lift forces as a function of angle of attack for Re of
15714 and 37143.
Wind turbine power performance was evaluated in terms of power coefficient values.
Laboratory measurements showed that improvements were obtained on the electrical
power values, resulting in an average increase of 90% in the corresponding power coefficient
values. A more pronounced enhancement is described at lower wind speed values.
CFD calculations were performed at flow values of 6 and 14 m/s to the C-D device.
CFD calculations performed an evaluation of velocity experienced in the action rotor
zone, which provided maximum increases of 81 % and 86 %, respectively.
Numerical simulations and experimental measurements were performed also to the
blades, where the results obtained were similar, providing a difference of 25 % for drag
forces.<br>Neste trabalho estudou-se o efeito do concentrador-difusor (C-D) numa turbina eólica encapsulada.
O principal objetivo deste estudo é avaliar o incremento que o C-D induz na
produtividade de turbinas eólicas de pequena dimensão. Foi também avaliado o desempenho
aerodinâmico de dois modelos de uma pá com diferentes razões de escala. Estes
modelos foram avaliados em termos de forças de arrasto e de sustentação em função do
ângulo de ataque, considerando Reynolds de 15714 e 37143.
O desempenho energético da turbina foi avaliada em termos de coeficiente de potência.
Segundo as medições laboratoriais verificou-se melhorias nos valores de potência
elétrica, resultando num aumento médio de 90 %, nos correspondentes valores de coeficiente
de potência. Para valores de velocidade mais baixos verificou-se um incremente
mais pronunciado.
Efetuaram-se simulações CFD ao dispositivo C-D para valores de velocidade de vento
de 6 e 14 m/s. Estas simulações reproduziram uma avaliação dos valores de velocidade
do ar verificados na zona de ação do rotor, produzindo aumentos máximos de 81 % e 86
%, respetivamente.
Aplicaram-se também medições experimentais e simulações numéricas para avaliar o
desempenho aerodinâmico da pá. Estas produziram resultados similares, originando uma
diferença média de 25 % nos valores das forças de arrasto.
Book chapters on the topic "Diffuser augmented wind turbine"
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Surya, S., Jayakrishnan Radhakrishnan, and Amit Kumar. "Effect of Slits in Diffuser Casing of Diffuser Augmented Wind Turbines(DAWTs)." In Lecture Notes in Mechanical Engineering. Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0698-4_25.
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Bacus, Delan S., and Cresencio P. Genobiagon. "Design and Simulation of Diffuser Augmented Wind Turbine (DAWT) for Urban Areas." In Lecture Notes in Electrical Engineering. Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1577-2_44.
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Nurur Rochman, M., Aulia Nasution, and Gunawan Nugroho. "CFD Studies on the Flanged Diffuser Augmented Wind Turbine with Optimized Curvature Wall." In ICoSI 2014. Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-287-661-4_35.
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S. P. da Costa, Mariana, Joss Kesby, and Philip D. Clausen. "Structural Optimisation of 3D Printed Small Diffuser Augmented Wind Turbine Blade Using Bi-directional Evolutionary Layout Optimisation Method." In Wind Energy Exploitation in Urban Environment. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13531-7_13.
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Unser, Logan, and Ahmad Vasel-Be-Hagh. "A Preliminary Evaluation on the Performance of Diffuser-Augmented Vertical Axis Wind Turbines." In Springer Proceedings in Energy. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-38804-1_10.
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Agha, Arouge, and Hassam N. Chaudhry. "A Computational Fluid Dynamics (CFD) Study on Enhancing Green Building Performance in Dubai, UAE Using Diffuser Augmented Wind Turbines (DAWT)." In Sustainable Civil Infrastructures. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61645-2_8.
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Sorribes-Palmer, Félix, Antonio Figueroa-González, Ángel Sanz-Andrés, and Santiago Pindado. "Wind Turbine Diffuser Aerodynamic Study with OpenFOAM $$^{\textregistered }$$." In OpenFOAM®. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-60846-4_37.
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Tefera, Abiyu Mersha, Abdulkadir Aman, and Muluken Temesgen Tigabu. "Experimental Investigation of Augmented Horizontal Axis Wind Turbine." In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43690-2_42.
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"8. Diffuser-Augmented Small-Scale Wind Turbine." In Wind Energy Harvesting. De Gruyter, 2018. http://dx.doi.org/10.1515/9781614514176-008.
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Badawy, M. T. S., and M. E. Aly. "Theoretical Demonstration of Diffuser Augmented wind Turbine Performance." In World Renewable Energy Congress VI. Elsevier, 2000. http://dx.doi.org/10.1016/b978-008043865-8/50497-9.
Full textConference papers on the topic "Diffuser augmented wind turbine"
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Elbakry, Hossam M., Ahmed A. A. Attia, Osama Ezzat Abdelatif, and M. S. Zahran. "Simulation of Diffuser Augmented Wind Turbine performance." In 2016 World Congress on Sustainable Technologies (WCST). IEEE, 2016. http://dx.doi.org/10.1109/wcst.2016.7886589.
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Jhamb, J., A. Rajawat, and P. Ranjan. "CFD Study of Diffuser Augmented Micro Wind Turbine." In 2019 8th International Conference on Power Science and Engineering (ICPSE). IEEE, 2019. http://dx.doi.org/10.1109/icpse49633.2019.9041156.
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Wang, Jifeng, Janusz Piechna, Blake Gower, and Norbert Mu¨ller. "Diffuser-Augmented Composite Material Wind Turbine Design Using CFD." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62145.
Full textAbstract:
A novel manufacturing approach similar to filament winding is able to produce high-performance and light-weight composite wheels in a rapid, inexpensive way by utilizing commercially available winding machines. In this study, a numerical investigation of a diffuser-augmented composite wind turbine is evaluated with a conventional bare wind turbine by using FLUENT in conjunction with the GAMBIT meshing tool. The extracted torque and power are calculated and compared for these two modeling designs. The simulation results show that the extracted power of a diffuser-augmented turbine can be 5 times the power extracted by a bare turbine of the same turbine area. This analysis procedure provides an insight into the hydrodynamic design and operation of a diffuser-augmented wind turbine in order to shorten the design period and improve technical performance.
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Abdelrahman, Hazem H., Ahmed M. R. Elbaz, and Ahmed M. Elkholy. "Low Wind Speed Characteristics of an Optimized Diffuser Augmented Wind Turbine." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-82052.
Full textAbstract:
Abstract Towards a final aim of enhancing the feasibility of low-speed sites for wind energy generation, the current study introduces the diffuser augmentation as a method of enhancing the performance of wind turbines designed for poor wind conditions. The study uses a methodology that combines the MOGAII Genetic Algorithm (GA) and Computational Fluid Dynamics (CFD) to generate a novel optimized diffuser profile out of nearly 200 geometric shapes. A case for each of the bare turbine and the diffuser-augmented turbine were modeled using 3-dimensional Reynolds Averaged Navier Stokes equations (RANS) using k-ω SST model and FLUENT solver. The performance comparison indicated an overall average rise of 28.83% in power coefficient in favor of the diffuser-augmented case. The most significant performance rise of 47.19% was found at the low-speed region corresponding to Tip Speed Ratios between 8 and 12. Through investigating the starting torque at extremely low speeds above 1 m/s, it was evaluated that the starting torque increases significantly with an average rise of 60.64% in favor of the diffuser-augmented case, the enhanced starting torque widened the operational range of the wind turbine in the low wind speed region, and reduced the lowest required speed to induce a positive moment coefficient. This significant rise in performance particularly for low wind speeds which are dominantly more frequent in the annual wind conditions, combined with the enhanced starting capabilities, resulted in an annual generated energy increase of 23.18% compared to the bare turbine.
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Dighe, Vinit V., Francesco Avallone, Juan Tang, and Gerard van Bussel. "Effects of Gurney Flaps on the Performance of Diffuser Augmented Wind Turbine." In 35th Wind Energy Symposium. American Institute of Aeronautics and Astronautics, 2017. http://dx.doi.org/10.2514/6.2017-1382.
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Kulak, Michal, Maciej Karczewski, Krzysztof Olasek, and Krzysztof Jozwik. "CFD analysis of Diffuser Augmented Wind Turbine model for wind tunnel investigation." In IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2016. http://dx.doi.org/10.1109/iecon.2016.7794041.
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Tourlidakis, A., K. Vafiadis, V. Andrianopoulos, and I. Kalogeropoulos. "Aerodynamic Design and Analysis of a Flanged Diffuser Augmented Wind Turbine." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95640.
Full textAbstract:
Many researchers proposed methods for improving the efficiency of small Horizontal Axis Wind Turbines (HAWTs). One of the methods developed to increase the efficiency of HAWTs and to overcome the theoretical Betz limit is the introduction of a converging – diverging casing around the turbine. To further improve the performance of the diffuser a flange is placed at its outlet, which smoothes the flow along the diffuser interior, allowing larger diffusion angles to be utilized. The purpose of this research work is the aerodynamic design and computational analysis of such an arrangement with the use of Computational Fluid Dynamics (CFD). First, a HAWT rotor rotating at 600 RPM was designed with the use of the Blade Element Momentum (BEM) method. The three rotor blades are constructed using the NREL airfoil sections family S833, S834 and S835. The power coefficient of the rotor was optimised in a wind speed range of 5 – 10 m/s, with a maximum value of 0.45 for a wind speed of 7m/s. A full three-dimensional CFD analysis was carried out for the modeling of the flow around the rotor and through the flanged diffuser. The computational domain consisted of two regions with different frames of reference (a stationary and a rotating). The rotating frame rotates at 600 RPM and includes the rotor with the blades. All the simulations were performed using the commercial CFD software package ANSYS CFX. The Shear Stress Transport turbulence model was used for the simulations. Detailed flow analysis results are presented, dealing with the various investigated test cases, a) isolated turbine rotor, b) diffuser without the presence of the turbine, and c) the full turbine – diffuser arrangement for different flange heights and wind speeds. By varying the height of the flange and the wind speed, the effects of the above on the flow field and the power coefficient of the turbine were studied. The CFD resulting power coefficients are also compared and good agreement with existing in the literature experimental data was obtained. The results showed that there is a significant improvement in the performance of the wind turbine (by a factor from 2 to 5 on power coefficient at high blade tip speed ratio) and the proposed modification is particularly attractive for small wind turbines. The particular characteristics of the flow field, that are responsible for this improvement are identified and analysed in detail offering a better understanding of the physical processes involved.
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M. S., Kiran, Aakash Rajawat, and Pritanshu Ranjan. "3-D Computational Study of a Diffuser Augmented Micro Wind Turbine." In ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65661.
Full textAbstract:
Abstract The present study focuses on the design optimization of a 3D DAMWT (Diffuser Augmented Micro Wind Turbine geometry). DAMWTS are compact devices with a swept area of only few square meters and energy production capacity of a few kilowatts. Their small size makes it convenient for domestic power generation. The box-shaped shroud makes it possible to stack multiple DAMWTS in an array configuration, thereby multiplying power output. 3-D CFD simulations were carried out using the k-ω SST turbulence model to compare the performance characteristics of different turbine geometries with a square inlet. With a constant shroud diffuser angle of 12 degrees as obtained in a previous study, the shroud nozzle angle and curvature were varied to obtain the maximum velocity factor and minimize flow stagnation at the inlet. Best performance was obtained with a nozzle angle of approximately 27 degrees and semi-concave curvature, with a velocity factor of 1.2. Further increase in nozzle angle resulted in a decline in performance and an increased flow stagnation. To analyze the influence of stacking on flow characteristics, a computational study of two DAMWTS placed horizontally next to each other was carried out. An investigation of the effectiveness of Vortex Generators in inhibiting flow stagnation at the inlet was also conducted.
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Mohanan, Janesh N., S. Kumaravel, and S. Ashok. "Performance Analysis of Diffuser Augmented Wind Turbine/Battery-Hybrid Energy System." In 2022 IEEE Delhi Section Conference (DELCON). IEEE, 2022. http://dx.doi.org/10.1109/delcon54057.2022.9753617.
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Surya, S., Ashwini Anand Gaonkar, and R. Jayakrishnan. "Design and Analysis of Diffuser Casings for Diffuser Augmented Wind Turbines." In 2020 4th International Conference on Green Energy and Applications (ICGEA). IEEE, 2020. http://dx.doi.org/10.1109/icgea49367.2020.239688.
Full textReports on the topic "Diffuser augmented wind turbine"
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Guntur, S., S. Schreck, N. N. Sorensen, and L. Bergami. Modeling dynamic stall on wind turbine blades under rotationally augmented flow fields. Office of Scientific and Technical Information (OSTI), 2015. http://dx.doi.org/10.2172/1215179.
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