Experimental and Numerical Investigations on Drag and Torque Characteristics of Three-Bladed Savonius Wind Turbine
01 Jan 2009-pp 85-94
TL;DR: In this paper, the aerodynamic performance of the vertical axis Savonius wind turbine has been investigated using wind tunnel analysis and computational fluid dynamics (CFD) simulation, and these results are compared with the corresponding experimental results for verification.
Abstract: With the growing demand of energy worldwide, conventional energy is becoming more and more scarce and expensive. The United States is already facing an energy crunch as the fuel price soars. Therefore, there is an obvious need for alternative sources of energy—perhaps more than ever. Wind is among the most popular and fastest-growing forms of electricity generation in the world, which is pollution free and available almost at any time of the day, especially in the coastal regions. The main attraction of the vertical-axis wind turbine is its manufacturing simplicity compared to that of the horizontal-axis wind turbine. Among all different vertical axis wind turbines, Savonius wind turbine is the simplest one. Operation of the Savonius wind turbine is based on the difference of the drag force on its semi-spherical blades, depending on whether the wind is striking the convex or the concave part of the blades. The advantage of this type of wind turbine is its good self-starting and wind directional independence characteristic. It, however, has a relatively lower efficiency in comparison with the lift type vertical-axis wind turbines. Due to its simple design and low construction cost, Savonius rotors are primarily used for water pumping and wind power on a small scale. The main objective of this ongoing research work is to improve the aerodynamic performance of vertical axis Savonius wind turbine. Wind tunnel investigation has been performed on aerodynamic characteristics, such as drag coefficients, and static torque coefficient of three-bladed Savonius rotor model. Also the computational fluid dynamics (CFD) simulation has been performed using FLUENT software to analyze the static rotor aerodynamics such as drag coefficients and torque coefficient, and these results are compared with the corresponding experimental results for verification.Copyright © 2009 by ASME
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TL;DR: In this article, a series of wind tunnel investigations on semi-cylindrical three-bladed Savonius rotor scale models with different overlap ratios and without overlap were conducted in front of a low-speed subsonic wind tunnel at different Reynolds numbers.
Abstract: The purpose of this research work is to investigate experimentally and computationally the feasibility of improving the performance of the vertical-axis Savonius wind turbine. The authors first performed a series of wind tunnel investigations on semi-cylindrical three-bladed Savonius rotor scale models with different overlap ratios and without overlap. These experiments were conducted in front of a low-speed subsonic wind tunnel at different Reynolds numbers. Pressures around the concave and convex surfaces of each blade, as well as the static torque for the rotor models, were measured. Using these experimental data, the authors calculated aerodynamic characteristics such as drag coefficients, static torque coefficients, and power coefficients. The authors then performed computational fluid dynamics (CFD) simulations using the commercial CFD software FLUENT and GAMBIT to analyze the static rotor aerodynamics of those models. The experimental and computational results were then compared for verification. Three different models with different overlap ratios were designed and fabricated for the current study to find the effect of overlap ratios. The results from the experimental part of the research show a significant effect of overlap ratio and Reynolds number on the improvement of aerodynamic performance of the Savonius wind turbine. At higher Reynolds number, the turbine model without overlap ratio gives better aerodynamic coefficients, and at lower Reynolds number, the model with moderate overlap ratio gives better results.
52 citations
Cites methods from "Experimental and Numerical Investig..."
...[9] conducted both experimental investigations and computational fluid dynamic (CFD) simulations to establish the feasibility of improving the performance of a simple, three-bladed Savonius VAWT....
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Dissertation•
01 Mar 2019
TL;DR: In this paper, the authors developed a simulation model in an open-source software package called OpenFOAM to investigate the performance characteristics of the Lux Vertical Axis Wind Turbine (VAWT).
Abstract: Wind energy can be characterized as a cheap, clean, and renewable energy source that is absolutely sustainable. With increasing demand for wind energy, it is productive to investigate the structural and operational factors that undermine the proficiency and the characteristic performance of the wind turbine. Of paramount importance to efficient wind energy generation is the aerodynamics of the wind turbine blades. The aerodynamic factors, such as drag, airfoil profiles, and wake interactions that often reduce the performance of the wind turbines, can be investigated through computational mathematics using computational fluid dynamics (CFD). CFD offers basic techniques and tools for simulating physical processes and proffers important insights into the flow data, which are demanding and costly to measure experimentally. In this thesis, we develop a simulation model in an open-source software package called OpenFOAM to investigate the performance characteristics of the Lux Vertical Axis Wind Turbine (VAWT). The Lux VAWT has a simpler design than its horizontal counterparts; however, its performance is affected by the unsteady aerodynamic due to a complex flow field. The turbulent flow field is governed by the incompressible Navier– Stokes equations. Simulations are carried out with an unsteady incompressible and dynamic flow solver, PimpleDyMFoam, on an unstructured mesh surface of the Lux VAWT geometry. The computational domain includes both the stationary and rotating mesh domains to accommodate the rotating motion of the turbine blades and the free-stream zone. The arbitrary mesh interface is applied as a boundary condition for the patches between the two domains to enable computation across disconnected but adjacent mesh domains. Meshing was done using two separate meshing tools, snappyHexMesh and ANSYS Mesher. The snappyHexMesh tool offered the most flexible and effective control over the mesh generation and quality. In order to derive the maximal power output from the Lux VAWT simulations, the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations are solved with different time-stepping methods; the objective is to reduce the computational costs. While attempting to reduce the numerical diffusion from the non-transient terms of URANS, a stabilized trapezoidal rule with a second-order backward differentiation formula (TR–BDF2) time-stepping method was implemented in OpenFOAM. As a result, the transient aerodynamic forces of the blades, the torque, and power output are evaluated. The findings demonstrate that most of the transient aerodynamic force is generated along the axis of rotation of the rotor during one complete revolution. Similarly, the computations indicate that the BDF2 method results in the least computational cost and predicts a turbine power that is somewhat comparable to the experimental results. The difference between the simulation results and the experimental data is attributed partly to the pressure fluctuations on the turbine blades due to the mesh topology.
9 citations
01 Jan 2014
TL;DR: In this paper, 3Dimensional CAD models of various simple airfoils have been designed in Solidworks and other shape, CFD simulation has been performed with five different VAWT designed models.
Abstract: Wind alone can fulfill most of the energy requirement of the world by its efficient conversion in to energy. Though Horizontal Axis Wind Turbine (HAWT) is more popular but needs high wind speed to generate energy. On the other hand Vertical Axis Wind Turbine (VAWT) needs low wind speed and can be installed anywhere which are some of the reasons for this research. The main objective of this research is to improve the design and performance of VAWT to make it more attractive, efficient, durable and sustainable. For a VAWT the blades perform the main role to extract energy from the wind. Airfoil is considered as the blade for this new design of VAWT. Airfoil has some good aerodynamic characteristics, match with the characteristics of Savonius type VAWT, such as good stall characteristics and little roughness effect, relatively high drag and low lift coefficient. Integration of Computational Fluid Dynamics (CFD) simulation and wind tunnel experimentation has made the current research more acceptable. 3-Dimensional CAD models of various simple airfoils have been designed in Solidworks. Using these airfoils and other shape, CFD simulation has been performed with five different VAWT designed models. Moving mesh and fluid flow simulation have been developed in CFD software FLUENT. The findings of these numerical simulations provided pressure contour, velocity contour, drag coefficient, lift coefficient,
5 citations
TL;DR: In this article, the effects of the straight blade angle on the turbine performance were studied, and it was concluded that the turbine with a straight blade angles of 100° model gives the better performance at higher Tip Sped Ratio (TSR) than other models.
Abstract: The present paper aims to numerically investigate the two-dimensional flow analysis of modified Savonius wind turbine using computational fluid dynamics. The effects of the straight blade angle on the turbine performance were studied. Simulations based on the RANS equations and the SST-k-w turbulence model are used to simulate the airflow over the turbine blades. Both the static and dynamic simulations were performed. In the static simulation, the drag and lift coefficient on the Savonius turbine were directly calculated at every angular position, and the time-averaged moment and power coefficients were computed in each of the dynamic simulations. From the results, it can be concluded that the turbine with a straight blade angle of 100° model gives the better performance at higher Tip Sped Ratio (TSR) than other models.
4 citations