Employing Computational Fluid Dynamics to Derive Beddoes–Leishman Model Airfoil Parameters for Vertical Axis Wind Turbines

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Brian Hand ◽  
Ger Kelly ◽  
Andrew Cashman
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Scale ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Experimental Measurements ◽  
Vertical Axis Wind Turbine ◽  
Modelling Methodology ◽  
Operating Limits ◽  
Aerodynamic Modelling

Abstract The blades of a vertical axis wind turbine (VAWT) experience large variations in the angle of attack at low tip-speed ratios and induce blade force oscillation. These unsteady aerodynamic effects must be considered in the VAWT aerodynamic modelling methodology by utilizing a dynamic stall model. The Beddoes–Leishman (B–L) dynamic stall model is a popular method to simulate the unsteady VAWT blade dynamic stall aerodynamics. However, a limitation of the B–L dynamic stall model is the number of the airfoil dependent parameters derived from both steady and unsteady experimental measurements. In this paper, a methodology is described to compute these B–L dynamic stall model airfoil coefficients utilizing a computational fluid dynamics (CFD) model. This method permits the calculation of the blade dynamic stall characteristics over a range of reduced pitch rates by employing a user-defined sliding mesh motion technique. Furthermore, the variation in the blade Reynolds number is accounted for by conducting simulations at the maximum and minimum VAWT envelope operating limits. Aerodynamic blade force experimental measurements are used to compare the predictions from a low-order model with airfoil data extracted CFD and experiments. This approach expands the applicability of the B–L dynamic stall model for large-scale VAWTs.

Development of a Computational Fluid Dynamics Methodology to Reproduce the Effects of Macroturbulence on Wind Turbines and Its Application to the Particular Case of a VAWT

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Francesco Balduzzi ◽  
Marco Zini ◽  
Giovanni Ferrara ◽  
Alessandro Bianchini
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Wind Turbines ◽  
Large Scale ◽  
Maximum Level ◽  
Vertical Axis ◽  
Energy Yield ◽  
Vertical Axis Wind Turbine ◽  
Wind Tunnel Data

Abstract Based on existing reports and databases, most of the installations in highly turbulent sites in fact fail to reach the expected energy yield, resulting in still or underperforming turbines that also give bad press for the technology. A better understanding of the real performance of wind turbines under highly turbulent conditions is then pivotal to ensure the economic viability of new installations. To this end, the possible use of computational fluid dynamics (CFD) techniques could provide notable benefits, reducing the time-to-market and the cost with respect to experiments. On the other hand, it is intrinsically not easy to reproduce properly intense and large-scale turbulence with the techniques of common use for research and industry (e.g., CFD unsteady Reynolds-averaged Navier–Stokes (URANS)), while the only methods that are granted to do so (e.g., direct numerical simulation (DNS) or large eddy simulation (LES)) are often not computationally affordable. Moving from this background, this study presents the development of a numerical strategy to exploit at their maximum level the capabilities of an unsteady RANS approach in order to reproduce fields of macroturbulence of use for wind energy applications. The study is made of two main parts. In the first part, the numerical methodology is discussed and assessed based on real wind tunnel data. The benefits and drawbacks are presented also in comparison to other existing methods. In the second part, it has been used to simulate the behavior under turbulence of a H Darrieus vertical-axis wind turbine, for which unique wind tunnel data were available. The simulations, even if preliminary, showed good matching with experiments (e.g., confirming the increase of power), showing then the potential of the method.

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.

Investigation of Self-Starting Capability of Vertical Axis Wind Turbines Using a Computational Fluid Dynamics Approach

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire ◽  
Robert J. Ribando
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Mesh Deformation ◽  
Operating Speed ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance

Vertical axis wind turbines have always been a controversial technology; claims regarding their benefits and drawbacks have been debated since the initial patent in 1931. Despite this contention, very little systematic vertical axis wind turbine research has been accomplished. Experimental assessments remain prohibitively expensive, while analytical analyses are limited by the complexity of the system. Numerical methods can address both concerns, but inadequate computing power hampered this field. Instead, approximating models were developed which provided some basis for study; but all these exhibited high error margins when compared with actual turbine performance data and were only useful in some operating regimes. Modern computers are capable of more accurate computational fluid dynamics analysis, but most research has focused on horizontal axis configurations or modeling of single blades rather than full geometries. In order to address this research gap, a systematic review of vertical axis wind-power turbine (VAWT) was undertaken, starting with establishment of a methodology for vertical axis wind turbine simulation that is presented in this paper. Replicating the experimental prototype, both 2D and 3D models of a three-bladed vertical axis wind turbine were generated. Full transient computational fluid dynamics (CFD) simulations using mesh deformation capability available in ansys-CFX were run from turbine start-up to operating speed and compared with the experimental data in order to validate the technique. A circular inner domain, containing the blades and the rotor, was allowed to undergo mesh deformation with a rotational velocity that varied with torque generated by the incoming wind. Results have demonstrated that a transient CFD simulation using a two-dimensional computational model can accurately predict vertical axis wind turbine operating speed within 12% error, with the caveat that intermediate turbine performance is not accurately captured.

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