scholarly journals Fluid dynamic mechanisms of enhanced power generation by closely spaced vertical axis wind turbines

2016 ◽  
Vol 99 ◽  
pp. 1213-1226 ◽  
Author(s):  
Stefania Zanforlin ◽  
Takafumi Nishino
Keyword(s):  
Power Generation ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Dynamic Mechanisms ◽  
Vertical Axis Wind Turbines

Aerodynamic Measurements on a Vertical Axis Wind Turbine in a Large Scale Wind Tunnel

2010 ◽  
Author(s):  
L. Battisti ◽  
L. Zanne ◽  
S. Dell’Anna ◽  
V. Dossena ◽  
B. Paradiso ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Optimization ◽  
Vertical Axis Wind Turbines

This paper presents the first results of a wide experimental investigation on the aerodynamics of a vertical axis wind turbine. Vertical axis wind turbines have recently received particular attention, as interesting alternative for small and micro generation applications. However, the complex fluid dynamic mechanisms occurring in these machines make the aerodynamic optimization of the rotors still an open issue and detailed experimental analyses are now highly recommended to convert improved flow field comprehensions into novel design techniques. The experiments were performed in the large-scale wind tunnel of the Politecnico di Milano (Italy), where real-scale wind turbines for micro generation can be tested in full similarity conditions. Open and closed wind tunnel configurations are considered in such a way to quantify the influence of model blockage for several operational conditions. Integral torque and thrust measurements, as well as detailed aerodynamic measurements were applied to characterize the 3D flow field downstream of the turbine. The local unsteady flow field and the streamwise turbulent component, both resolved in phase with the rotor position, were derived by hot wire measurements. The paper critically analyses the models and the correlations usually applied to correct the wind tunnel blockage effects. Results evidence that the presently available theoretical correction models does not provide accurate estimates of the blockage effect in the case of vertical axis wind turbines. The tip aerodynamic phenomena, in particular, seem to play a key role for the prediction of the turbine performance; large-scale unsteadiness is observed in that region and a simple flow model is used to explain the different flow features with respect to horizontal axis wind turbines.

Recent Advances in Rotor Design of Vertical Axis Wind Turbines

2012 ◽  
Vol 36 (6) ◽  
pp. 647-665 ◽  
Author(s):  
David MacPhee ◽  
Asfaw Beyene
Keyword(s):  
Power Generation ◽  
Wind Power ◽  
Recent Work ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Wind Power Generation ◽  
Small Scale ◽  
Rotor Design ◽  
Vertical Axis Wind Turbines ◽  
Design And Testing

The following work represents the most recent advances in design and testing of vertical axis wind turbines (VAWT) rotors. VAWTs have received much attention as of late due to proposed advantages in small scale and off grid wind power generation. Thus, many recent works have surfaced involving analysis, design and optimization of VAWT rotors in order to more efficiently convert wind energy to electricity or other readily usable means. This paper is a collection of most of the recent literature works involving VAWT rotor design and testing, the majority of which published after 2005. We discuss research in the designing of various lift based rotors as well as some drag based rotors, hybrids, and various others. The recent work in this area suggests VAWT capacity could dramatically increase in the near future, and play a vital role in obtaining cleaner, more sustainable energy when global energy demand is increasing at an unprecedented rate. HIGHLIGHTS A review of various works involving rotor design and testing of both lift and drag Vertical Axis Wind Turbines (VAWTs) is presented; Benefits of vertical axis wind turbines in small scale and off grid wind power generation is summarized; Much of the recent work, published after 2005, has been directed towards analyzing, designing, and optimizing rotor shapes. The body of this recent work suggests that research on VAWT rotor design continues to flourish and could make VAWTs a viable competitor to more traditional Horizontal Axis Wind Turbines (HAWTs) worldwide.

The Aerodynamic Performance of Offshore Twin Vertical Axis Wind Turbines With Deflector

2019 ◽  
Author(s):  
Yichen Jiang ◽  
Peidong Zhao ◽  
Li Zou ◽  
Guiyong Zhang ◽  
Zhi Zong
Keyword(s):  
Wind Turbines ◽  
Dynamic Method ◽  
Fluid Dynamic ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Vertical Axis Wind Turbines ◽  
Simulation Results ◽  
Novel Design ◽  
Local Angle

Abstract A novel design of offshore twin counter-rotating vertical axis wind turbines (VAWTs) with deflector is proposed in this paper. We investigate the performance of the twin VAWTs by the two-dimensional computational fluid dynamic method with the Spalart-Allmaras turbulence model. Then, the performances of twin VAWTs with three kinds of deflectors are compared. The results show that installing the front deflector leads to significant improved aerodynamic performance. To better understand the simulation results, we introduce a simple and effective method to obtain the blade’s angle of attack. The mechanism of enhanced performance by deflector is pointed out, based on the information of the blade’s local angle of attack and flow field. Finally, a guideline on the design of deflector for the twin vertical axis wind turbines is provided.

scholarly journals Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5564
Author(s):  
Rosario Lanzafame ◽  
Stefano Mauro ◽  
Michele Messina ◽  
Sebastian Brusca
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Time Step ◽  
Vertical Axis Wind Turbines ◽  
2D Model

The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

Adaptive surface distortions for torque ripple control in vertical-axis wind turbines

2019 ◽  
pp. 0309524X1987402 ◽  
Author(s):  
Gareth Erfort ◽  
Theodor W von Backström ◽  
Gerhard Venter
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Torque Ripple ◽  
Small Scale ◽  
Blade Design ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Vertical Axis Wind Turbines

Vertical-axis wind turbines have been confined to small-scale generation in urban environments where their omnidirectional capability offers them an advantage over the more ubiquitous horizontal-axis wind turbine. With a drive towards renewable energy, more opportunities exist for the implementation of wind turbines in a multitude of environments. Based on its inherent operational drawbacks, the vertical-axis wind turbine has not undergone extensive investigation. Recently, there has been a resurgence of interest in the technology. This article addresses the torque ripple, a variation in torque produced by the turbine, present during operation. The variation in torque generated by a vertical-axis wind turbine increases the likelihood of failure due to fatigue. Current treatment is symptomatic and addresses the result of the torque fluctuation and not the cause. A novel blade design, capable of altering the lift and drag response through shape alteration, is presented as a solution. The blade design and operation is achieved through genetic algorithm optimization and computational fluid dynamic simulations. Comparisons with previous work show the novel blade presented here surpasses the reduction seen with pitching solutions. A 25% reduction in torque ripple was demonstrated for a 17% reduction in performance coefficient using the surface distortion approach. This surpasses the foil pitching approach which achieved a 15% torque ripple reduction for the same loss in performance coefficient.

Aerodynamic Measurements on a Vertical Axis Wind Turbine in a Large Scale Wind Tunnel

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
L. Battisti ◽  
L. Zanne ◽  
S. Dell’Anna ◽  
V. Dossena ◽  
G. Persico ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Optimization ◽  
Vertical Axis Wind Turbines

This paper presents the first results of a wide experimental investigation on the aerodynamics of a vertical axis wind turbine. Vertical axis wind turbines have recently received particular attention, as interesting alternative for small and micro generation applications. However, the complex fluid dynamic mechanisms occurring in these machines make the aerodynamic optimization of the rotors still an open issue and detailed experimental analyses are now highly recommended to convert improved flow field comprehensions into novel design techniques. The experiments were performed in the large-scale wind tunnel of the Politecnico di Milano (Italy), where real-scale wind turbines for micro generation can be tested in full similarity conditions. Open and closed wind tunnel configurations are considered in such a way to quantify the influence of model blockage for several operational conditions. Integral torque and thrust measurements, as well as detailed aerodynamic measurements were carried out to characterize the 3D flow field downstream of the turbine. The local unsteady flow field and the streamwise turbulent component, both resolved in phase with the rotor position, were derived by hot wire measurements. The paper critically analyses the models and the correlations usually applied to correct the wind tunnel blockage effects. Results highlight that the presently available theoretical correction models do not provide accurate estimates of the blockage effect in the case of vertical axis wind turbines. The tip aerodynamic phenomena, in particular, seem to play a key role for the prediction of the turbine performance; large-scale unsteadiness is observed in that region and a simple flow model is used here to explain the different flow features with respect to horizontal axis wind turbines.

Modeling and Numerical Simulation for the Newly Designed Four Cavity Blades Vertical Axis Wind Turbine

2014 ◽  
Vol 554 ◽  
pp. 536-540
Author(s):  
Kadhim Suffer ◽  
Ryspek Usubamatov ◽  
Ghulam Abdul Quadir ◽  
Khairul Azwan Ismail
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Horizontal Axis Wind Turbines ◽  
The Individual

The last years have proved that Vertical Axis Wind Turbines (VAWTs) are more suitable for urban areas than Horizontal Axis Wind Turbines (HAWTs). To date, very little has been published in this area to assess good performance and lifetime of VAWTs either in open or urban areas. The main goal of this current research is to investigate numerically the aerodynamic performance of a newly designed cavity type vertical axis wind turbine having four blades. In the current new design the power generated depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. For numerical investigation, commercially available computational fluid dynamic CFD software GAMBIT and FLUENT were used. In this numerical analysis the Shear Stress Transport (SST) k-ω turbulence model is used which is better than the other turbulence models available as suggested by some researchers. The computed results show good agreement with published experimental results.

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