Computational fluid dynamics study of Savonius rotors using OpenFOAM

2020 ◽  
pp. 0309524X2092495
Author(s):  
Federico González Madina ◽  
Alejandro Gutiérrez ◽  
Pedro Galione
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Dynamics Simulation ◽  
Power Coefficient ◽  
Small Scale ◽  
Two Dimensional ◽  
Discretization Schemes ◽  
Set Up

In this work, two-dimensional models of Savonius rotors are simulated using OpenFOAM® in order to predict the aerodynamic performance of small-scale vertical-axis wind turbines. The results are reported analyzing the aerodynamic performance and forces acting on the rotors. Power coefficient, [Formula: see text], is compared with experimental data for each operation point, and for three different geometries. Simulations with first- and second-order discretization schemes are carried out and compared, both quantitative and qualitative. Since usual grid dimensions result not to be suitable for simulations of Savonius rotors, an analysis of different domains is performed and compared. Finally, a set up for computational fluid dynamics simulation of two-dimensional Savonius rotors is proposed. The fluid–rotor interaction is analyzed and the vortex shedding is correlated with [Formula: see text] values and wake description.

Detailed Analysis of the Wake Structure of a Straight-Blade H-Darrieus Wind Turbine by Means of Wind Tunnel Experiments and Computational Fluid Dynamics Simulations

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Alessandro Bianchini ◽  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Giacomo Persico ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Wind Turbines ◽  
Large Scale ◽  
Vertical Axis ◽  
Performance Estimation ◽  
Small Scale ◽  
Dynamics Simulations

Darrieus vertical axis wind turbines (VAWTs) have been recently identified as the most promising solution for new types of applications, such as small-scale installations in complex terrains or offshore large floating platforms. To improve their efficiencies further and make them competitive with those of conventional horizontal axis wind turbines, a more in depth understanding of the physical phenomena that govern the aerodynamics past a rotating Darrieus turbine is needed. Within this context, computational fluid dynamics (CFD) can play a fundamental role, since it represents the only model able to provide a detailed and comprehensive representation of the flow. Due to the complexity of similar simulations, however, the possibility of having reliable and detailed experimental data to be used as validation test cases is pivotal to tune the numerical tools. In this study, a two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (U-RANS) computational model was applied to analyze the wake characteristics on the midplane of a small-size H-shaped Darrieus VAWT. The turbine was tested in a large-scale, open-jet wind tunnel, including both performance and wake measurements. Thanks to the availability of such a unique set of experimental data, systematic comparisons between simulations and experiments were carried out for analyzing the structure of the wake and correlating the main macrostructures of the flow to the local aerodynamic features of the airfoils in cycloidal motion. In general, good agreement on the turbine performance estimation was constantly appreciated.

Two-Dimensional Computational Fluid Dynamics Study on the Performance of Twin Vertical Axis Wind Turbine With Deflector

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Yichen Jiang ◽  
Peidong Zhao ◽  
Li Zou ◽  
Zhi Zong ◽  
Kun Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
Energy Utilization ◽  
Offshore Wind ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Local Flow

Abstract The offshore wind industry is undergoing a rapid development due to its advantage over the onshore wind farm. The vertical axis wind turbine (VAWT) is deemed to be potential in offshore wind energy utilization. A design of the offshore vertical axis wind turbine with a deflector is proposed and studied in this paper. Two-dimensional computational fluid dynamics (CFD) simulation is employed to investigate the aerodynamic performance of wind turbine. An effective method of obtaining the blade’s angle of attack (AoA) is introduced in CFD simulation to help analyze the blade aerodynamic torque variation. The numerical simulations are validated against the measured torque and wake velocity, and the results show a good agreement with the experiment. It is found that the blade instantaneous torque is correlated with the local AoA. Among the three deflector configurations, the front deflector leads to favorable local flow for the blade, which is responsible for the improved performance.

Variable pitch control for vertical-axis wind turbines

2018 ◽  
Vol 42 (2) ◽  
pp. 128-135 ◽  
Author(s):  
S Horb ◽  
R Fuchs ◽  
A Immas ◽  
F Silvert ◽  
P Deglaire
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Variable Pitch ◽  
Pitch Control

NENUPHAR aims at developing the next generation of large-scale floating offshore vertical-axis wind turbine. To challenge the horizontal-axis wind turbine, the variable blade pitch control appears to be a promising solution. This article focuses on blade pitch law optimization and resulting power and thrust gain depending on the operational conditions. The aerodynamics resulting from the implementation of a variable blade pitch control are studied through numerical simulations, either with a three-dimensional vortex code or with two-dimensional Navier-stokes simulations (two-dimensional computational fluid dynamics). Results showed that the three-dimensional vortex code used as quasi-two-dimensional succeeded to give aerodynamic loads in very good agreement with two-dimensional computational fluid dynamics simulation results. The three-dimensional-vortex code was then used in three-dimensional configuration, highlighting that the variable pitch can enhance the vertical-axis wind turbine power coefficient ( Cp) by more than 15% in maximum power point tracking mode and decrease it by more than 75% in power limitation mode while keeping the thrust below its rated value.

Development of the Dual Vertical Axis Wind Turbine Using Computational Fluid Dynamics

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Gabriel Naccache ◽  
Marius Paraschivoiu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Urban Areas ◽  
High Efficiency ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Circular Path ◽  
Vertical Axis Wind Turbine

Small vertical axis wind turbines (VAWTs) are good candidates to extract energy from wind in urban areas because they are easy to install, service, and do not generate much noise; however, the efficiency of small turbines is low. Here-in a new turbine, with high efficiency, is proposed. The novel design is based on the classical H-Darrieus VAWT. VAWTs produce the highest power when the blade chord is perpendicular to the incoming wind direction. The basic idea behind the proposed turbine is to extend that said region of maximum power by having the blades continue straight instead of following a circular path. This motion can be performed if the blades turn along two axes; hence, it was named dual vertical axis wind turbine (D-VAWT). The analysis of this new turbine is done through the use of computational fluid dynamics (CFD) with two-dimensional (2D) and three-dimensional (3D) simulations. While 2D is used to validate the methodology, 3D is used to get an accurate estimate of the turbine performance. The analysis of a single blade is performed and the turbine shows that a power coefficient of 0.4 can be achieved, reaching performance levels high enough to compete with the most efficient VAWTs. The D-VAWT is still far from full optimization, but the analysis presented here shows the hidden potential and serves as proof of concept.

scholarly journals Improvement of Aerodynamic Performance of Savonius Wind Rotor Using Straight-Arc Curtain

2020 ◽  
Vol 10 (20) ◽  
pp. 7216
Author(s):  
Hongfu Zhang ◽  
Zhiqiang Li ◽  
Dabo Xin ◽  
Jian Zhan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Aerodynamic Performance ◽  
Power Coefficient ◽  
Mean Power ◽  
Negative Moment ◽  
Dynamic Performances ◽  
Dynamics Method ◽  
Static Torque

A straight and an arc-shaped curtain are combined to enhance the aerodynamic performance of the Savonius wind rotor. The straight-arc curtain is placed in front of the Savonius wind rotor to reduce the negative moment on the convex blade and increase the positive moment on the concave blade. The static and dynamic performances of the Savonius wind rotor with and without the curtain are investigated based on the computational fluid dynamics method. The results show that the static torque is higher with the curtain than without it at the same angle-of-attack. The maximum mean power coefficient with the curtain is increased by about 50% compared with conventional Savonius wind rotor. Additionally, the flow field around the rotor with the straight-arc curtain is presented, and the flow control mechanics of the straight-arc curtain are discussed.

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