Experimental investigations on single stage, two stage and three stage conventional savonius rotor
01 Aug 2008-International Journal of Energy Research (John Wiley & Sons, Ltd)-Vol. 32, Iss: 10, pp 877-895
TL;DR: In this paper, the performance of single stage (rotor aspect ratio of 1.0), two-stage and three-stage Savonius rotors were compared at different Reynolds numbers and compared at the same Reynolds number.
Abstract: The performance of single stage (rotor aspect ratio of 1.0), two stage Savonius rotor with rotor aspect ratios of 1.0 and 2.0 (stage aspect ratios of 0.50 and 1.0) and three stage Savonius rotor with rotor aspect ratios of 1.0 and 3.0 (stage aspect ratios of 0.33 and 1.0) are studied at different Reynolds numbers and compared at the same Reynolds number. The results show that the coefficient of power and the coefficient of torque increase with the increase in the Reynolds numbers for all the rotors tested. The coefficient of static torque is independent of the Reynolds number for all the rotors tested. The performance of two stage and three stage rotors remains the same even after increasing the stage aspect ratio and the rotor aspect ratio by a factor of two and three, respectively. For the same rotor aspect ratio of 1.0, by increasing the number of stages (stage aspect ratio decreases), the performance deteriorates in terms Cp and Ct. However, at the same stage aspect ratio of 1.0 and same Reynolds number, two and three stage rotors show the same performance in terms of coefficient of power and coefficient of torque. The variation in coefficient of static torque is lower for a three stage rotor when compared with the variation of coefficient of static torque for two stage or single stage rotor. Copyright © 2008 John Wiley & Sons, Ltd.
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TL;DR: In this paper, a helical Savonius rotor with a twist of 90° was proposed to decrease the variation in static torque from 0° to 360°, and the performance of the helical rotor with and without shaft was compared in an open jet wind tunnel.
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Abstract: Energy crisis and high emission of fossil fuels are major driving forces for developing renewable energy based technologies. In order to meet growing demand for energy, hydropower can be one of the sustainable alternatives. Further, the hydrokinetic turbine is considered as one of the most emerging technologies which harness energy from flowing water. In this paper, an attempt has been made to review hydrokinetic energy theory for energy conversion system from water currents analogous to wind power system. The most widespread classes of hydrokinetic turbines are discussed in detail with respect to their benefits, drawbacks and desirable conditions for applications. It has been found that in spite of some prevailing downsides of vertical axis turbine like of self-starting and lower efficiency, vertical axis turbines are appealing for many riverine applications. One of the prominent turbines of its kind is the Savonius hydrokinetic turbine that has the capacity to self-start at a very low fluid velocity in the river, canal etc. However, Savonius type hydrokinetic turbine inherently has poor efficiency. A number of experimental and numerical studies with a large number of physical designs and parameters have been carried out in the area of Savonius rotor to enhance its efficiency. Under this study, review of different parameters affecting the performance of Savonius hydrokinetic turbine has been carried out and presented in this paper which may be useful for future studies to improve the efficiency of such turbines.
132 citations
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References
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413 citations
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, a three-bladed rotor system has been tested in a low speed wind tunnel, and its performance has been compared with conventional semicircular blades (with twist angle of 0°) on the basis of starting characteristics, static torque and rotational speed.
248 citations
Journal Article•
242 citations