Showing papers on "Savonius wind turbine published in 2012"
TL;DR: In this paper, the authors present a review on the performance of Savonius wind turbines and present relevant information about their performance, bringing a discussion about the performance and benefits of using this type of turbines.
Abstract: This paper presents a review on the performance of Savonius wind turbines. This type of turbine is unusual and its application for obtaining useful energy from air stream is an alternative to the use of conventional wind turbines. Simple construction, high start up and full operation moment, wind acceptance from any direction, low noise and angular velocity in operation, reducing wear on moving parts, are some advantages of using this type of machine. Over the years, numerous adaptations for this device were proposed. The variety of possible configurations of the rotor is another advantage in using such machine. Each different arrangement of Savonius rotor affects its performance. Savonius rotor performance is affected by operational conditions, geometric and air flow parameters. The range of reported values for maximum averaged power coefficient includes values around 0.05–0.30 for most settings. Performance gains of up to 50% for tip speed ratio of maximum averaged power coefficient are also reported with the use of stators. Present article aims to gather relevant information about Savonius turbines, bringing a discussion about their performance. It is intended to provide useful knowledge for future studies.
337 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 influence of the buckets overlap ratio of a Savonius wind rotor on the averaged moment and power coefficients, over complete cycles of operation, is discussed, based on the commercial software Star-CCM+.
190 citations
TL;DR: In this paper, the authors present a historical perspective on the Savonius turbines and discuss recent developments in analysis methods which intend to optimize the turbines for powering cellular communication towers in developing parts of the world.
Abstract: Wind turbine use is expanding throughout the world as a means to provide electricity without contributing to the increase in global-warming gases. Most commonly, very large, horizontal-axis turbines are constructed in fleets that are connected to national-level electrical grid systems. More recently, there has been a desire for more local, small-scale power production that can be used to power very specific pieces of equipment or buildings. Some of the small-scale turbines are designed differently from their larger counterparts—they are driven by drag forces rather than by lift. Drag-driven turbines are typically called Savonius turbines. This paper, which presents a historical perspective on Savonius turbines, will illustrate their potential for providing local power. Finally, we will discuss recent developments in analysis methods which intend to optimize Savonius turbines for powering cellular communication towers in developing parts of the world.
82 citations
TL;DR: In this article, the experimental test results of Savonius-type vertical axis wind turbines (VAWT) with different overlap ratios and shift angles were presented, and three turbines with the overlap ratios of 0, 0.16 and 0.32 were designed and constructed.
51 citations
TL;DR: In this article, the authors explored the interaction effect of the overlap ratio, phase-shift, and stage on the performance of the Savonius rotors in details and showed that appropriate choice of the phase shift angle according to overlap ratio can not only increase the power coefficient but also eliminate the negative static torque and smooth the variation of the static torque coefficient.
Abstract: This paper presents the experimental results of the vertical axis wind turbine (VAWT), especially the Savonius rotors, which are developed for application on top of buildings due to lower wind speed compared with remote areas. The VAWT is regarded as the most suitable elegant candidate to be integrated with buildings for its relatively low operating noise, easy maintenance, and easy access. This study explored the interaction effect of the overlap ratio, phase-shift, and stage on the performance of the Savonius rotors in details. The results show that appropriate choice of the phase-shift angle according to the overlap ratio can not only increase the power coefficient of the Savonius rotors but also eliminate the negative static torque and smooth the variation of the static torque coefficient. Moreover, the performance of the two-stage rotors indicates that the two-stage rotor is the best candidate for this type of wind turbines or as a starting assistant for the Darrieus rotors.
42 citations
25 Jun 2012
TL;DR: This paper considers the general issues in the project and the optimization of energy generation systems using small universal wind turbines, suitable in Distributed Generation (DG) and computer aided optimization for a better exploitation of wind source.
Abstract: This paper considers the general issues in the project and the optimization of energy generation systems using small universal wind turbines, suitable in Distributed Generation (DG) and computer aided optimization for a better exploitation of wind source. Optimization in this field reveal to be more and more important because the local generation and consumption of electrical power, even for grid connected generators can suffers for unevenness of wind source exploitation, also in terms of wrong directions and in not regular wind flows. Computer aided design and optimization of small plants may give significant improvements in the development of the wind source also in accordance with the projections of future energy policies that foresee a significant increase of the wind generated energy for the future market. The effectiveness of computer aided optimization tools is illustrated in the present paper with the exposition of two case studies. In the first of them a Wind Electrical Energy Generating System is moved by a Modular Multiple Blade Fixed Pitch Wind Turbine coupled with an asynchronous wound rotor generator. In the second case study the optimization regards a Savonius wind turbine and a PM synchronous generator with particular reference to the development of wind source for the wind turbine and the reduction of saturation and of harmonic content in the emf for the electrical machines.
39 citations
Patent•
26 Mar 2012
TL;DR: A wind turbine of the savonius wind turbine type comprises a rotatable member extending along a longitudinal axis and a plurality of blades extending radially outwards from the rotatable members and spaced apart around the circumference thereof as discussed by the authors.
Abstract: A wind turbine, of the savonius wind turbine type, comprises a rotatable member extending along a longitudinal axis and a plurality of blades extending radially outwards from the rotatable member and spaced apart around the circumference thereof. The rotatable member is arranged such that, in normal use, the longitudinal axis extends in a substantially vertical direction and the blades travel around the longitudinal axis. The wind turbine further comprising a wind deflector operable to deflect wind to provide a sheltered region for the blades as they travel towards the wind and thereby substantially reducing the drag induced on the turbine.
11 citations
TL;DR: In this paper, the structural improvement information of Savonius wind turbine is summarized in order to provide useful knowledge for the researchers in the structural design and improvement of the wind turbine, which can bring huge differences in turbine performance, especially the differences in the maximum wind energy utilization (Cp-max) with different structure.
Abstract: This paper summarizes the research results of the structural parameters which have effects on the performance of Savonius wind turbine. Savonius wind turbine being used in wind power and tidal power belongs to vertical axis wind turbine (VAWT). Recently, more and more research have placed on it for its advantages such as: being able to accept wind from any direction, long fatigue life of the blades, high starting torque, wide working wind speed range, easy to install, manufacture and maintain and low noise etc. The performance of Savonius wind turbine is affected by many factors. Different structural parameters can bring huge differences in turbine performance. Especially the differences in the maximum wind energy utilization (Cp-max) can be more than 30% with different structure. Many new turbines get higher Cp-max by improving the structural parameters. In this paper, the structural improvement information of Savonius wind turbine is summarized in order to provide useful knowledge for the researchers in the structural design and improvement.
11 citations
31 Dec 2012
TL;DR: In this paper, an omni-direction-guide-vane (ODGV) was used to improve the performance of a vertical axis wind turbine (VAWT) in a high-rise building for wind tunnel testing.
Abstract: A novel omni-direction-guide-vane (ODGV) that surrounds a vertical axis wind turbine (VAWT) is designed to improve the wind turbine performance. A scaled model was constructed to simulate a Savonius VAWT enclosed by the ODGV on top of high-rise building for wind tunnel testing. Torque, rotational speed and power output were measured using a torque transducer with hysteresis brake applied to the rotor shaft. With the aid of the ODGV, the highest increment in rotational speed (11.4%) was achieved at a wind speed of 3 m/s (at free-running condition). The ODGV also increased the power coefficient, Cp of the VAWT at all tested wind speeds and the maximum (Cp = 0.26) was achieved at the tip speed ratio, TSR = 0.95 for a wind speed of 3 m/s. The highest increment of Cp (56.9%) was obtained at the same TSR and wind speed. With this design, the size of VAWT can be reduced for a given power output.
8 citations
TL;DR: In this paper, a new bucket configuration for Savonius wind generator is proposed with the aim to increase the effect of the overlap ratio RS on the wind turbine performances and increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis.
Abstract: In this paper a new bucket configuration for Savonius wind generator is proposed. With the aim to increase the effect of the overlap ratio RS on the wind turbine performances and to increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis. The numerical analyses are performed by Comsol Multiphysics® and the results obtained for a Savonius wind turbine with overlap only are compared to numerical and experimental benchmarks. Parametric analyses are performed, for fixed overlap ratio, by varying the slot angle β and the results show that for low angle β the Savonius rotor exploits improved performance at low tip speed ratio λ, evidencing a better starting torque. This circumstance is confirmed by the static analyses performed on the slotted blades in order to investigate the starting characteristic of the proposed Savonius wing generator configuration.
Patent•
21 Nov 2012
TL;DR: In this paper, a combined vertical axis wind turbine consisting of a Savonius wind turbine, a Darrieus wind turbine and a vertical rod and a non-contact overrun clutch is described.
Abstract: A combined vertical axis wind turbine comprises a Savonius wind turbine, a Darrieus wind turbine, a vertical rod and a non-contact overrun clutch. The non-contact overrun clutch comprises an outer ring, an inner ring, a wedge block device, a fixing retaining ring, a retaining collar, two end caps, two bearings, a retaining ring and a torsion spring, wherein the inner ring is mounted on a shaft extension of the Savonius wind turbine, the outer ring is supported by the two bearings mounted on the inner ring and is connected with the Darrieus wind turbine prior to being fastened together with the two end caps through screws, and the Savonius wind turbine is connected with the Darrieus wind turbine through the overrun clutch and is arranged above the Darrieus wind turbine. The combined vertical axis wind turbine has the advantages that self-starting of the Darrieus wind turbine is achieved, and hindering influences of the Savonius wind turbine on the Darrieus wind turbine after starting of the Darrieus wind turbine are avoided, so that the performance of the combined vertical axis wind turbine is optimal.
Journal Article•
TL;DR: In this article, the authors present a way to improve efficiency by increasing the number of blades and by covering the convex part of the blades behind a shield or vane, which has a more stable torque along the rotation and therefore presents a better starting ability.
Abstract: The efficiency of the Savonius wind turbine is low because of its unstable torque and also due to the negative drag exerted on the convex part of the blades.That negative drag creates a negative torque lowering the efficiency.At some wind angles,the standard Savonius rotor can't even start rotating.This study presents a way to improve efficiency by increasing the number of blades and by covering the convex part of the blades behind a shield or vane.Multi-bladed Savonius rotors have a more stable torque along the rotation and therefore present a better starting ability;their power coefficient can also be higher than the standard Savonius rotors if the right parameters are used.Design parameters such as blade number and dimensions have a strong influence on the aerodynamic efficiency.
TL;DR: A novel efficiency boosting design feature in a drag type vertical axis wind turbine (VAWT) based on a series of smaller blade elements to make any shape, which changes to reduce a negative resistance as it rotates and thus maximizing the useful torque.
Abstract: The primary purpose of this research effort is to propose a novel efficiency boosting design feature in a drag type
vertical axis wind turbine (VAWT), explore practicality through design and fabrication, and test the viability of the
design through wind tunnel experiments. Using adaptive control surface design and an improved blade shape can be very
useful in harnessing the wind's energy in low wind speed areas. The new design is based on a series of smaller blade
elements to make any shape, which changes to reduce a negative resistance as it rotates and thus maximizing the useful
torque. As such, these blades were designed into a modified Savonius wind turbine with the goal of improving upon the
power coefficient produced by a more conventional design. The experiment yielded some positive observations with
regard to starting characteristics. Torque and angular velocity data was recorded for both the conventional configuration
and the newly built configuration and the torque and power coefficient results were compared.
TL;DR: In this article, the Savonius wind turbine with the guide vane was used and the micro bubble was generated by this wind turbine to purify the quality of water in eutrophic lakes and marshes.
Abstract: In recent years, pollution of the water in eutrophic lakes and marshes become an important problem. To improve this situation, we developed the water purification system by using the wind energy. In the present system, the Savonius wind turbine with the guide vane was used and the micro bubble was generated by this wind turbine to purify the quality of water. The most important characteristic of this system is to possess the wind energy conservation apparatus. That is, the wind was converted into the water pressure by using the accumulator to make the most use of the weak wind energy. To clarify the effectiveness of the present system, the field test was carried out. Test results showed that the micro-bubble was generated intermittently even in relatively low wind velocity condition, and the generation frequency of the micro-bubble was in proportion to the cube of the wind velocity.
TL;DR: In this article, a new innovative design of two Savonius rotors coaxially in the opposite direction is presented in the traditional generator, which can enhance the power generation efficiency of the wind turbine.
Abstract: Savonius rotor is a typical style of vertical-axis wind turbine (VAWT). A new innovative design of two Savonius rotors coaxially in the opposite direction is presented in the paper which is different from the traditional design. The traditional generator has only a pair of stator and rotor and matched with trational Savonius rotor. Enlarging the relative speed between the magnetic pole and the coil pole by making the two pole rotate in the opposite direction in the innovative Savonius wind turbine. In this way, it can enhance the power generation efficiency of the Savonius wind turbine. The fluid-solid coupling analysis for the Savonius wind turbine is used to calculate the power characteristics and efficiency of the wind turbine.