Improvement in Savonius Wind Turbines Efficiency by Modification of Blade Designs—A Numerical Study
01 Jun 2020-Journal of Energy Resources Technology-transactions of The Asme (American Society of Mechanical Engineers Digital Collection)-Vol. 142, Iss: 6, pp 1-15
TL;DR: The study indicates that the blade design presented here has a potential to increase the power efficiency of a Savonius wind turbine by 10–28%, which is a significant improvement in power efficiency.
Abstract:
Savonius wind turbines are special class of vertical axis wind turbines (VAWTs). These are low-cost drag-driven turbines and are known to be inefficient. It is proposed in this study that a simple modification to the turbine blade design can yield a significant improvement in power efficiency. The performance of the new design is extensively studied on openfoam-v1812, a popular open source computational fluid dynamics (CFD) library. The flow equations coupled with equations of rotation of the turbine are solved on an overset mesh framework. This study also serves as a validation of recently released overset support in openfoam. The turbulence is incorporated by coupling Reynolds-averaged Navier–Stokes (RANS) with shear stress transport (SST) κ − ω eddy viscosity turbulence model. The turbulence parameters are set to produce a flow with the Reynolds number, Re = 4.8 × 105. To have better confidence in simulations, this study also presents a comparison of numerical flow over conventional Savonius turbine designs with the published data. It is observed that a majority of CFD analysis on wind turbine designs are performed for the fixed tip speed ratio on a traditional static mesh structure. But, in this CFD study, a wind-driven rotation of Savonius turbine is simulated on an overset dynamics approach. The results of the study are compared and discussed based on the predicted moment and power coefficients, pressure variation on the blades, flow velocity field, and wake analysis. The study indicates that the blade design presented here has a potential to increase the power efficiency of a Savonius wind turbine by 10–28%.
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TL;DR: In this article, a review of the optimization studies of Savonius turbine regarding its probable applications in harnessing hydrokinetic energy is presented, and the studies concerning each of the structural parameters influencing the turbine performance are discussed thoroughly.
31 citations
TL;DR: In this article, an airfoil-shaped deflector was proposed and placed in front of the turbine to prevent the negative torque affecting the convex surface of the returning blade and also making it possible for deflecting the wind into the advancing blade.
Abstract: In the present study, a novel deflector system was proposed to improve the performance of a Savonius wind turbine through Computational Fluid Dynamics (CFD) simulation. For this purpose, an airfoil-shaped deflector was proposed and placed in front of the turbine to prevent the negative torque affecting the convex surface of the returning blade and also making it possible for deflecting the wind into the advancing blade. Different configurations of the proposed deflector system were considered numerically using the CFD solver. A three-dimensional incompressible unsteady Reynolds-averaged Navier–Stokes simulation in conjunction with the SST k − ω turbulence model was done and validated with the available experimental data. The predicted results indicated that the performance of the Savonius rotor is highly dependent on the position and angle of the deflector. Thus, there was an appropriate position and angle values to obtain the highest torque and power coefficients. It was concluded that using the favorable airfoil-shaped deflector significantly enhanced the static torque coefficient values in all angular ranges especially in the rotation angles between 0°–30° and 150°–180°. By properly covering the returning blade using the airfoil-shaped deflector, the static torque coefficient values increased up to two times higher than that generated by without deflector case.
20 citations
TL;DR: This paper investigates the insertion of a one-way opening valve on the three-blade Savonius wind turbine to reduce generated negative torque on convex side of the blade and exhibits 14% improvement in performance, which is promising.
Abstract:
Unacceptable environmental pollution from the fossil fuel energy sources is increasing the demands on green energy concept and developing alternative solutions and has encouraged the international community to employ clean and renewable energy sources such as wind energy. Among different types of wind turbines, Savonius vertical axis in spite of its fascinating advantages including low rotational speed and noise, self-start capability, and independency relative to wind direction has gained less attention in industry due to low energy conversion efficiency. This paper investigates the insertion of a one-way opening valve on the three-blade Savonius wind turbine to reduce generated negative torque on convex side of the blade. Position, size, opening direction, and the opening angle limitation are defined as design parameters and 17 different scenarios in five main categories based on these parameters are modeled, simulated, and analyzed. Concluding, unlimited counter-clockwise large valve in position III exhibits 14% improvement in performance, which is promising.
17 citations
TL;DR: The Savonius turbine is a prominent drag-based turbine used for harnessing wind or water power as mentioned in this paper, it can be customized for run-off river stream locations having ultra-low head.
16 citations
TL;DR: Various performance influencing parameters and the power augmentation techniques used for S-type VAWT have been studied and reported studies on these techniques have been reviewed.
16 citations
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