Wind tunnel and numerical study of a small vertical axis wind turbine (original) (raw)
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AIAA2008-1316 Wind Tunnel and Numerical Study of a Small Vertical Axis Wind Turbine
This paper presents a combined experimental and computational study into the aerodynamics and performance of a small scale vertical axis wind turbine. Wind tunnel tests were carried out to ascertain overall performance of the turbine and two and three dimensional unsteady CFD models were generated to help understand the aerodynamics of this performance.
Small-scale vertical-axis wind turbines can be used as a source of electricity in rural and urban environments. According to the authors' knowledge, there are no validated simplified aerodynamic models of these wind turbines, therefore the use of more advanced techniques, such as for example the computational methods for fluid dynamics is justified. The paper contains performance analysis of the small-scale vertical-axis wind turbine with a large solidity. The averaged velocity field and the averaged static pressure distribution around the rotor have been also analyzed. All numerical results presented in this paper are obtained using the SST k-ω turbulence model. Computed power coefficients are in good agreement with the experimental results. A small change in the tip speed ratio significantly affects the velocity field. Obtained velocity fields can be further used as a base for simplified aerodynamic methods.
Numerical analysis of vertical axis wind turbine
2014 9th International Forum on Strategic Technology (IFOST), 2014
A model for the aerodynamic evaluation of a vertical-axis wind turbine (VAWT) to improve its torque characteristics has been analysed. VAWT is more promising especially in areas with frequent light winds. This paper represent a numerical analysis of the aerodynamics performance on the straight blade fixed pitch VAWT (3 blades) based on the NACA 0018 airfoil. A solid modelling software ANSYS FLUENT which is linked to a finite volume Computational Fluid Dynamics (CFD) is used for the calculation of rotor performance. Gambit software is used to create 2D model of the turbine and the mesh which is generated in Fluent for numerical iterate solution. The Unsteady Reynolds averaged Navier-Stokes equation is used for the investigation of general effects on the performance of several geometry characteristics of two-dimensional airfoils. The RNG k-epsilon model is adopted for the turbulence closure. For proposed rotor analysis, flow field characteristics are investigated at different values of tip speed ratio and also the dynamic quantities such as rotor torque co-efficient and power co-efficient for a constant free stream velocity for 9 m/s which correspond to Reynolds numbers based on chord length of 2.6×10 5 . The VAWT has an inherent unsteady aerodynamic behaviour due to the variation of angle of attack with the angle of rotation, perceived velocity and consequentially Reynolds number. This approach is necessary for having a numerical analysis at low computational cost and time.
Numerical Study of a Small Horizontal-Axis Wind Turbine Aerodynamics Operating at Low Wind Speed
Fluids
The present work aims to study the aerodynamic characteristics of a newly designed three-bladed horizontal-axis wind turbine (HAWT) using the Computational Fluid Dynamic (CFD) method. The blade geometry is designed using an improved Blade Element Momentum (BEM) method to be similar in size to the Ampair300 wind turbine. The shear stress transport (SST) transition turbulence model closure is utilized to solve the steady state three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations. The Ansys Fluent CFD solver is used to solve the problem. Then, a comparison between the two turbines’ operating conditions is conducted by monitoring the pressure coefficient, pressure contours and velocity vectors at five different radial positions. The analysis of the Tip Speed Ratio (TSR) effects on the turbine efficiency and on the flow behavior on the blade and in the near wake is carried out. For 8 m/s wind speed, the optimum pitch angle is also investigated, and the results are prepared ...
A Computational Study of The Effect of Blade Thickness on Performance of Vertical Axis Wind Turbine
Vertical axis wind turbine with straight blade is one of the modern vertical axis wind turbines for converting wind to electrical energy. Power production capability at low speed and turbulent winds and, low disturbing noise with good appearance, makes it suitable to use small scale of this type turbine in urban areas. In view of considering importance of blade aerodynamics in turbine performance, the flow over vertical axis wind turbine with straight blade is simulated by two dimensional computational fluid dynamics. In this regard, several conventional NACA series airfoils are chosen and the effect of airfoil thickness on turbine performance was studied. Blade geometry and grid generation were created in Gambit modeling software and, Fluent software which is based on finite volume method is used for solving the problem. For Numerical solution of unsteady flow around the airfoil, the Reynolds Averaged Navier-Stokes (RANS) have been used. The simulation results and comparison of power coefficient of vertical axis wind turbine in different thickness blades showed NACA 0012 airfoil has the best coefficient of performance in a range of tip speed ratio (λ>4). Such values are selected for tip speed ratio, so that the dynamic stall area of the blade to be prevented.
2018
Due to the importance and advantages of Vertical-axis wind turbines (VAWTs) over traditional horizontal-axis wind turbines (HAWTs), this paper is implemented. Savonius turbines with drag-based rotors are adopted from the two more extensive arrangements of vertical wind turbines because of their advantages. In this paper, six diverse rotor plans with measure up to cleared regions are analyzed with exploratory wind burrow testing and numerical reenactments. These proposed models incorporate a conventional Savonius with two different edges criteria and 90 degree helical bend models with two, three and four sharp edges. The models were designed using SolidWorks software then the physical models were 3D printed for testing. A subsonic open-sort wind burrow was utilized for Revolution per Minute (RPM) and torque estimation over a scope of wind speeds. ANSYS Fluent reenactments were utilized for dissecting streamlined execution by using moving reference outline and sliding lattice display ...
Journal of Fluid Science and Technology, 2015
This paper presents a numerical simulation and experiment on the effect of the variable pitch angle on the performance of a small vertical-axis wind turbine (VAWT) with straight blades. The power coefficient of the VAWT was measured in an open-circuit wind tunnel. By conducting two-dimensional unsteady computational fluid dynamics simulations using the RNG k-ε, Realizable k-ε, and SST k-ω models, the power and torque of the VAWT and the flow around the straight blades were also analyzed. The numerical simulation of the power performance results were validated using wind tunnel experimental data. The results of both the numerical simulations and experiments showed that a VAWT with variable-pitch blades has better performance than a VAWT with fixed-pitch blades. The numerical simulation of the performance using the RNG k-ε turbulence model had good qualitative agreement with the experimental results. The numerical simulation was able to capture the flow separation on a blade, and it was shown that a variable-pitch blade can suppress the flow separation on its blades at a tip speed ratio lower than that of fixed-pitch blades.
International journal of turbomachinery, propulsion and power, 2019
The paper presents the results of a computational study on the aerodynamics and the performance of a small-scale Vertical-Axis Wind Turbine (VAWT) for distributed micro-generation. The complexity of VAWT aerodynamics, which are inherently unsteady and three-dimensional, makes high-fidelity flow models extremely demanding in terms of computational cost, limiting the analysis to mainly 2D or 2.5D Computational Fluid-Dynamics (CFD) approaches. This paper discusses how a proper setting of the computational model opens the way for carrying out fully 3D unsteady CFD simulations of a VAWT. Key aspects of the flow model and of the numerical solution are discussed, in view of limiting the computational cost while maintaining the reliability of the predictions. A set of operating conditions is considered, in terms of tip-speed-ratio (TSR), covering both peak efficiency condition as well as off-design operation. The fidelity of the numerical predictions is assessed via a systematic comparison with the experimental benchmark data available for this turbine, consisting of both performance and wake measurements carried out in the large-scale wind tunnel of the Politecnico di Milano. The analysis of the flow field on the equatorial plane allows highlighting its time-dependent evolution, with the aim of identifying both the periodic flow structures and the onset of dynamic stall. The full three-dimensional character of the computations allows investigating the aerodynamics of the struts and the evolution of the trailing vorticity at the tip of the blades, eventually resulting in periodic large-scale vortices.
Influences of some parameters on the performance of a small vertical axis wind turbine
Renewable Energy and Environmental Sustainability, 2016
The effects of various parameters on the performance of a straight bladed vertical axis wind turbine, using the vortex model, have been numerically investigated. A vortex model has been used to evaluate the performance of a vertical axis wind turbine, by means of aerodynamic characteristics of different airfoils for Reynolds numbers between 10 5 and 10 6. Parameters such as the thickness and the camber of the blade airfoil, the solidity, the type of blade profile, the number of blades and the pitch angle, which influence the power coefficient, C P , and the start-up regime. This study can be used in the designing an optimal vertical axis wind turbine in a specific location, when the prevailed wind regime is known.
Aerodynamic Performance of Vertical-Axis Wind Turbines
Journal of Marine Science and Engineering
The nonstationary separated incompressible flows around Darrieus and Savonius rotors of vertical-axis wind turbines were investigated through computational simulation using the Reynolds averaged Navier–Stokes equations and Spalart–Allmaras turbulence model. The implicit finite-volume algorithm, the basis of which was artificial compressibility method, was chosen to obtain the numerical solution. The series of computational and physical experiments for Darrieus rotors with varied numbers and shapes of blades were performed. The detailed visualization of the flow was presented. The turbulent flows surrounding the Darrieus and Savonius rotors were studied, and as a part of these investigations, the major phases of vortex progress were identified. For this purpose, three series of computer tests on the aerodynamic and power properties of Savonius rotors with two and three buckets were performed, and their results are also presented. The influence of tip-speed ratio, solidity, and Reynol...