Performance and Aeroacoustic Noise Prediction for an Array of Small-Scale Vertical Axis Wind Turbines

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters. The results show that when the ratio of the shaft diameter to the wind turbine diameter (α) is 9%, the power loss of the wind turbine in one revolution increases from 0% to 25% relative to that of no-shaft wind turbine (this is a numerical experiment for which the shaft of the VAWT is removed in order to study the interactions between the shaft and blade). When the downstream blades pass through the wake of the shaft, the pressure gradient of the suction side and pressure side is changed, and an adverse effect is also exerted on the lift generation in the blades. In addition, α = 5% is a critical value for the rotating shaft wind turbine (the lift-drag ratio trend of the shaft changes differently). In order to figure out the impacts of four factors; namely, tip speed ratios (TSRs), α, turbulence intensity (TI), and the relative surface roughness value (ks/ds) on the performance of a VAWT system, the Taguchi method is employed in this study. The influence strength order of these factors is featured by TSRs > ks/ds > α > TI. Furthermore, within the range we have analyzed in this study, the optimal power coefficient (Cp) occurred under the condition of TSR = 4, α = 5%, ks/ds = 1 × 10−2, and TI = 8%.

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Numerical investigations of the effect of rotating and non-rotating shaft on aerodynamic performance of small scale urban vertical axis wind turbines

Journal of Renewable and Sustainable Energy ◽

10.1063/1.5025078 ◽

2018 ◽

Vol 10 (4) ◽

pp. 043302

Author(s):

Lidong Zhang ◽

Kaiqi Zhu ◽

Tieliu Jiang ◽

Ling Zhang ◽

Shaohua Li ◽

...

Keyword(s):

Wind Turbines ◽

Vertical Axis ◽

Aerodynamic Performance ◽

Small Scale ◽

Rotating Shaft ◽

Numerical Investigations ◽

Vertical Axis Wind Turbines

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Recent Advances in Rotor Design of Vertical Axis Wind Turbines

Wind Engineering ◽

10.1260/0309-524x.36.6.647 ◽

2012 ◽

Vol 36 (6) ◽

pp. 647-665 ◽

Cited By ~ 19

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.

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Computing Aerodynamic Performances of Small-Scale Vertical-Axis Wind Turbines: Possibilities and Challenges

Experimental and Computational Investigations in Engineering - Lecture Notes in Networks and Systems ◽

10.1007/978-3-030-58362-0_7 ◽

2020 ◽

pp. 91-111

Author(s):

Jelena Svorcan ◽

Marija Baltić ◽

Ognjen Peković

Keyword(s):

Wind Turbines ◽

Vertical Axis ◽

Small Scale ◽

Vertical Axis Wind Turbines ◽

Aerodynamic Performances

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Aerodynamics of small-scale vertical-axis wind turbines

Journal of Propulsion and Power ◽

10.2514/3.22882 ◽

1986 ◽

Vol 2 (3) ◽

pp. 282-288 ◽

Cited By ~ 2

Author(s):

Ion Paraschivoiu ◽

Philippe Desy

Keyword(s):

Wind Turbines ◽

Vertical Axis ◽

Small Scale ◽

Vertical Axis Wind Turbines

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Formulation, Validation, and Application of a Novel 3D BEM Tool for Vertical Axis Wind Turbines of General Shape and Size

Applied Sciences ◽

10.3390/app11135874 ◽

2021 ◽

Vol 11 (13) ◽

pp. 5874

Author(s):

Andrea G. Sanvito ◽

Vincenzo Dossena ◽

Giacomo Persico

Keyword(s):

Wind Tunnel ◽

Wind Turbines ◽

Three Dimensional ◽

Vertical Axis ◽

Small Scale ◽

Engineering Practice ◽

Blade Profile ◽

General Shape ◽

Vertical Axis Wind Turbines ◽

Shape And Size

Low order models based on the Blade Element Momentum (BEM) theory exhibit modeling issues in the performance prediction of Vertical Axis Wind Turbines (VAWT) compared to Computational Fluid Dynamics, despite the widespread engineering practice of such methods. The present study shows that the capability of BEM codes applied to VAWTs can be greatly improved by implementing a novel three-dimensional set of high-order corrections and demonstrates this by comparing the BEM predictions against wind-tunnel experiments conducted on three small-scale VAWT models featuring different rotor design (H-shaped and Troposkein), blade profile (NACA0021 and DU-06-W200), and Reynolds number (from 0.8×105 to 2.5×105). Though based on the conventional Double Multiple Stream Tube (DMST) model, the here-presented in-house BEM code incorporates several two-dimensional and three-dimensional corrections including: accurate extended polar data, flow curvature, dynamic stall, a spanwise-distributed formulation of the tip losses, a fully 3D approach in the modeling of rotors featuring general shape (such as but not only, the Troposkein one), and accounting for the passive effects of supporting struts and pole. The detailed comparison with experimental data of the same models, tested in the large-scale wind tunnel of the Politecnico di Milano, suggests the very good predictive capability of the code in terms of power exchange, torque coefficient, and loads, on both time-mean and time-resolved basis. The peculiar formulation of the code allows including in a straightforward way the usual spanwise non-uniformity of the incoming wind and the effects of skew, thus allowing predicting the turbine operation in a realistic open-field in presence of the environmental boundary layer. A systematic study on the operation of VAWTs in multiple environments, such as in coastal regions or off-shore, and highlighting the sensitivity of VAWT performance to blade profile selection, rotor shape and size, wind shear, and rotor tilt concludes the paper.

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Floating Offshore Vertical Axis Wind Turbines: Opportunities, Challenges and Way Forward

Energies ◽

10.3390/en14238000 ◽

2021 ◽

Vol 14 (23) ◽

pp. 8000

Author(s):

Abel Arredondo-Galeana ◽

Feargal Brennan

Keyword(s):

Wind Turbines ◽

Deep Water ◽

Wind Farm ◽

Structural Integrity ◽

Wind Farms ◽

Vertical Axis ◽

Offshore Wind ◽

Small Scale ◽

Offshore Wind Farms ◽

Vertical Axis Wind Turbines

The offshore wind sector is expanding to deep water locations through floating platforms. This poses challenges to horizontal axis wind turbines (HAWTs) due to the ever growing size of blades and floating support structures. As such, maintaining the structural integrity and reducing the levelised cost of energy (LCoE) of floating HAWTs seems increasingly difficult. An alternative to these challenges could be found in floating offshore vertical axis wind turbines (VAWTs). It is known that VAWTs have certain advantages over HAWTs, and in fact, some small-scale developers have successfully commercialised their onshore prototypes. In contrast, it remains unknown whether VAWTs can offer an advantage for deep water floating offshore wind farms. Therefore, here we present a multi-criteria review of different aspects of VAWTs to address this question. It is found that wind farm power density and reliability could be decisive factors to make VAWTs a feasible alternative for deep water floating arrays. Finally, we propose a way forward based on the findings of this review.

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Experimental and Numerical Investigations on Drag and Torque Characteristics of Three-Bladed Savonius Wind Turbine

Volume 6: Emerging Technologies: Alternative Energy Systems; Energy Systems: Analysis, Thermodynamics and Sustainability ◽

10.1115/imece2009-10838 ◽

2009 ◽

Cited By ~ 1

Author(s):

Mosfequr Rahman ◽

Khandakar N. Morshed ◽

Jeffery Lewis ◽

Mark Fuller

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Vertical Axis ◽

The United States ◽

Small Scale ◽

Horizontal Axis Wind Turbine ◽

Drag Coefficients ◽

Vertical Axis Wind Turbines ◽

Torque Coefficient ◽

Savonius Wind Turbine

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.

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Simulation of Vertical Axis Wind Turbines With Variable Pitch Foils

Volume 6B: Energy ◽

10.1115/imece2013-65694 ◽

2013 ◽

Author(s):

L. Damon Woods ◽

John F. Gardner ◽

Kurt S. Myers

Keyword(s):

Wind Turbines ◽

High Efficiency ◽

Empirical Studies ◽

Vertical Axis ◽

Small Scale ◽

Variable Pitch ◽

Vertical Axis Wind Turbines ◽

Dynamic Generator ◽

Turbine Design ◽

Very High

A dynamic computer model of a turbine was developed in MATLAB in order to study the behavior of vertical axis wind turbines (VAWTs) with variable pitch (articulating) foils. The simulation results corroborated the findings of several empirical studies on VAWTs. The model was used to analyze theories of pitch articulation and to inform the discussion on turbine design. Simulations of various models showed that pitch articulation allowed Darrieus-style vertical axis wind turbines to start from rest. Once in motion, the rotor was found to accelerate rapidly to very high rotational velocities. The simulations revealed a plateau region of high efficiency for small-scale Darrieus-style VAWTs with symmetric airfoils at tip speed ratios in the range of 3 to 4 and demonstrated the advantages of using a dynamic generator load.

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