Harvesting wind energy for improving performance of Savonius rotor
TL;DR: In this paper, three methods of controlling the wind direction were proposed aiming at improving the performance of Savonius rotor, which achieved a power-coefficient peak of 0.52 with operation range of tip speed ratio λ ≤ 2.2.
About: This article is published in Journal of Wind Engineering and Industrial Aerodynamics.The article was published on 2015-04-01. It has received 125 citations till now. The article focuses on the topics: Vertical axis wind turbine & Tip-speed ratio.
Citations
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TL;DR: In this paper, the authors highlight some of the major developments of VAWTs, with a focus on the integration with urban infrastructure, and draw several recommendations based on the state-of-the-art information on the subject for future studies and acceptance of wind turbines in the urban areas.
Abstract: Wind energy is one of the most promising renewable energy resources for power generation, and rapid growth has been seen in its acceptance since 2000. The most acceptable classification for wind turbines is by its axis of orientation: Horizontal Axis Wind Turbines (HAWT) and Vertical Axis Wind Turbines (VAWT). HAWTs are used in many countries for medium-to-large scale power projects, and most commercial installations around the globe are solely based on these turbines. On the other hand, HAWTs are not recognized as a viable option to harness the energy of the wind in urban areas, where the wind is less intense, much more chaotic and turbulent. VAWTs are suggested as a better choice for cities and isolated semi-urban areas. Several attributes have been suggested for the large-scale deployment of VAWTs, e.g., good performance under the weak and unstable wind, no noise and safety concerns, and aesthetically sound for integration in urban areas. Significant research has been published on wind turbine technology and resources assessment methodologies, and this review paper is a modest attempt to highlight some of the major developments of VAWTs, with a focus on the integration with urban infrastructure. Several recommendations have been drawn based on the state-of-the-art information on the subject for future studies and acceptance of wind turbines in the urban areas. It was concluded that further research is critical in making VAWTs a viable, dependable, and affordable power generation technology for many low and decentralized power applications.
168 citations
TL;DR: In this paper, the authors extensively review various flow augmentation systems and attempts to provide information to researchers on current augmentation techniques and other relevant research, which is able to increase the coefficient of power, CP, hence improving the output power of different types of VAWTs.
Abstract: There are many advantages of vertical axis wind turbines (VAWTs) compared with horizontal axis wind turbines (HAWTs). Research has shown that VAWTs are more suitable for turbulent wind flow and urban applications. However, the efficiency and low self-start ability of VAWTs are always the main drawbacks especially for the lift-type VAWTs. Unlike HAWTs, the rotor blades for VAWTs do not always provide positive torque during operation. Many innovative designs have been implemented to improve the performance of VAWTs, and this includes different configurations and blade profiles. This paper extensively reviews various flow augmentation systems and attempts to provide information to researchers on current augmentation techniques and other relevant research. The flow augmentation system is able to increase the coefficient of power, CP, hence improving the output power of different types of VAWTs. Some augmentation systems are able to increase the maximum power output by up to 910%. The methods and designs used to increase upwind velocity and to reduce negative torque created on the wind turbine have been discussed in detail. Additionally, the flow augmentation devices that are integrated with building structures are also reported in this paper.
127 citations
TL;DR: In this paper, a modified Savonius rotor with different convex and concave sides is optimized to maximize the power efficiency, and a particle swarm optimization (PSO) algorithm is applied to find the optimal design based on the response surface model.
127 citations
TL;DR: In this paper, a 2D unsteady simulation is performed for semicircular, Benesh, modified Bach and elliptical profiles keeping the overall rotor diameter in each case to be constant.
85 citations
TL;DR: In this paper, the authors proposed an optimal shape of the concave and convex sides of a hydraulic Savonius turbine to maximize the output power of the turbine by modifying the blade profile.
84 citations
References
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TL;DR: In this article, a Savonius rotor wind turbine was tested in the Vought Corporation Systems Division 4.9- x 6.1m Low Speed Wind Tunnel to determine aerodynamic performance.
Abstract: Fifteen configurations of a Savonius rotor wind turbine were tested in the Vought Corporation Systems Division 4.9- x 6.1-m Low Speed Wind Tunnel to determine aerodynamic performance. The range of values of the varied parameters was as follows: number of buckets, 2 and 3; nominal freestream velocity, 7 and 14 m/s; Reynolds number per meter, 4.32 x 10/sup 5/ and 8.67 x 10/sup 5/; rotor height, 1 and 1.5 m; rotor diameter (nominal), 1 m; bucket overlap, 0.0 to 0.1 m. The measured test variables were torque, rotational speed, and tunnel conditions. It is concluded that increasing Reynolds number and/or aspect ratio improves performance. The recommended configuration consists of two sets of two-bucket rotors, rotated 90 deg apart, with each rotor having a dimensionless gap width of 0.1 to 0.15.
381 citations
TL;DR: In this paper, the optimal position of the deflector plate upstream to the water flow was investigated to find out the maximum power generated by a Savonius rotor with water as the working medium at a Reynolds number of 1.32 × 10 5.
241 citations
TL;DR: In this paper, different geometries of Savonius wind turbine are experimentally studied in order to determine the most effective operation parameters, it was found that, the two blades rotor is more efficient than three and four ones.
Abstract: For solving the world energy problem and the bad effect of conventional sources of energy on environment, great attention allover the world is paid towards the use of renewable energy sources. Special interest is paid towards wind energy because of its competitively.
Savonius rotor is a vertical axis wind turbine which is characterized as cheaper, simpler in construction and low speed turbine. This makes it suitable for generating mechanical energy in many countries especially in Egypt.
In this work different geometries of Savonius wind turbine are experimentally studied in order to determine the most effective operation parameters. It was found that, the two blades rotor is more efficient than three and four ones. The rotor with end plates gives higher efficiency than those of without end plates. Double stage rotors have higher performance compared to single stage rotors. The rotors without overlap ratio (β) are better in operation than those with overlap. The results show also that the power coefficient increases with rising the aspect ratio (α). The conclusions from the measurements of the static torque for each rotor at different wind speeds verify the above summarized results of this work.
231 citations
TL;DR: In this paper, the position of an obstacle shielding the returning blade of the Savonius turbine and possibly leading to a better flow orientation toward the advancing blade is optimized. And the optimization process takes into account the output power coefficient as target function, considers the position and the angle of the shield as optimization parameters, and relies on Evolutionary Algorithms.
206 citations
TL;DR: In this article, the aerodynamic performance and flow fields of Savonius rotors at various overlap ratios have been investigated by measuring the pressure distributions on the blades and by visualizing the flow fields in and around the rotors with and without rotation.
205 citations