scholarly journals Rotor solidity effects on the performance of vertical-axis wind turbines at high Reynolds numbers

2018 ◽  
Vol 1037 ◽  
pp. 052015 ◽  
Author(s):  
M.A. Miller ◽  
S. Duvvuri ◽  
W.D. Kelly ◽  
M. Hultmark
Keyword(s):  
Wind Turbines ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Vertical Axis Wind Turbines ◽  
High Reynolds Numbers ◽  
High Reynolds

scholarly journals A double-multiple streamtube model for vertical axis wind turbines of arbitrary rotor loading

2019 ◽  
Vol 4 (4) ◽  
pp. 653-662 ◽  
Author(s):  
Anis A. Ayati ◽  
Konstantinos Steiros ◽  
Mark A. Miller ◽  
Subrahmanyam Duvvuri ◽  
Marcus Hultmark
Keyword(s):  
Wind Turbines ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Test Facility ◽  
Speed Ratio ◽  
Momentum Theory ◽  
Vertical Axis Wind Turbines ◽  
High Reynolds ◽  
New Formulation ◽  
Power Measurements

Abstract. We introduce an improved formulation of the double-multiple streamtube (DMST) model for the prediction of the flow quantities of vertical axis wind turbines (VAWT). The improvement of the new formulation lies in that it renders the DMST valid for any induction factor, i.e., for any combination of rotor solidity and tip speed ratio. This is done by replacing the Rankine–Froude momentum theory of the DMST, which is invalid for moderate and high induction factors, with a new momentum theory recently proposed, which provides sensible results for any induction factor. The predictions of the two DMST formulations are compared with VAWT power measurements obtained at Princeton's High Reynolds number Test Facility, over a range of tip speed ratios, rotor solidities, and Reynolds numbers, including those experienced by full-scale turbines. The results show that the new DMST formulation demonstrates a better overall performance, compared to the conventional one, when the rotor loading is moderate or high.

scholarly journals Design and Testing of a LUT Airfoil for Straight-Bladed Vertical Axis Wind Turbines

2018 ◽  
Vol 8 (11) ◽  
pp. 2266 ◽  
Author(s):  
Shoutu Li ◽  
Ye Li ◽  
Congxin Yang ◽  
Xuyao Zhang ◽  
Qing Wang ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Optimization Method ◽  
Geometrical Parameters ◽  
Vertical Axis Wind Turbines ◽  
University Of Technology ◽  
Horizontal Axis Wind Turbines

The airfoil plays an important role in improving the performance of wind turbines. However, there is less research dedicated to the airfoils for Vertical Axis Wind Turbines (VAWTs) compared to the research on Horizontal Axis Wind Turbines (HAWTs). With the objective of maximizing the aerodynamic performance of the airfoil by optimizing its geometrical parameters and by considering the law of motion of VAWTs, a new airfoil, designated the LUT airfoil (Lanzhou University of Technology), was designed for lift-driven VAWTs by employing the sequential quadratic programming optimization method. Afterwards, the pressure on the surface of the airfoil and the flow velocity were measured in steady conditions by employing wind tunnel experiments and particle image velocimetry technology. Then, the distribution of the pressure coefficient and aerodynamic loads were analyzed for the LUT airfoil under free transition. The results show that the LUT airfoil has a moderate thickness (20.77%) and moderate camber (1.11%). Moreover, compared to the airfoils commonly used for VAWTs, the LUT airfoil, with a wide drag bucket and gentle stall performance, achieves a higher maximum lift coefficient and lift–drag ratios at the Reynolds numbers 3 × 105 and 5 × 105.

scholarly journals Understanding the Aerodynamic Behavior and Energy Conversion Capability of Small Darrieus Vertical Axis Wind Turbines in Turbulent Flows

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2936 ◽  
Author(s):  
Francesco Balduzzi ◽  
Marco Zini ◽  
Andreu Carbó Molina ◽  
Gianni Bartoli ◽  
Tim De Troyer ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Wind Turbines ◽  
Energy Content ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbines ◽  
Performance Variation ◽  
Highly Turbulent Flows ◽  
Physical Phenomena

Small Darrieus vertical-axis wind turbines (VAWTs) have recently been proposed as a possible solution for adoption in the built environment as their performance degrades less in complex and highly-turbulent flows. Some recent analyses have even shown an increase of the power coefficient for the large turbulence intensities and length scales typical of such environments. Starting from these insights, this study presents a combined numerical and experimental analysis aimed at assessing the physical phenomena that take place during the operation of a Darrieus VAWT in turbulent flows. Wind tunnel experiments provided a quantification of the performance variation of a two-blade VAWT rotor for different levels of turbulence intensity and length scale. Furthermore, detailed experiments on an individual airfoil provided an estimation of the aerodynamics at high turbulence levels and low Reynolds numbers. Computational fluid dynamics (CFD) simulations were used to extend the experimental results and to quantify the variation in the energy content of turbulent wind. Finally, the numerical and experimental inputs were synthetized into an engineering simulation tool, which can nicely predict the performance of a VAWT rotor under turbulent conditions.

scholarly journals A Double Multiple Streamtube model for Vertical Axis Wind Turbines of arbitrary rotor loading

2019 ◽  
Author(s):  
Anis A. Ayati ◽  
Konstantinos Steiros ◽  
Mark A. Miller ◽  
Subrahmanyam Duvvuri ◽  
Marcus Hultmark
Keyword(s):  
Wind Turbines ◽  
Vertical Axis ◽  
Test Facility ◽  
Speed Ratio ◽  
Momentum Theory ◽  
Vertical Axis Wind Turbines ◽  
Overall Performance ◽  
High Reynolds ◽  
New Formulation ◽  
Power Measurements

Abstract. We introduce an improved formulation of the Double Multiple Streamtube (DMST) model for the prediction of the flow quantities of Vertical Axis Wind Turbines (VAWT). The improvement of the new formulation lies in that it renders the DMST valid for any induction factor, i.e. for any combination of rotor solidity and tip speed ratio. This is done by replacing the Rankine-Froude momentum theory of the DMST, which is invalid for moderate and high induction factors, with a new momentum theory recently proposed, which provides sensible results for any induction factor. The predictions of the two DMST formulations are compared with VAWT power measurements obtained at Princeton's High Reynolds number Test Facility, over a range of tip speed ratios, rotor solidities and Reyonlds numbers, including those experienced by full scale turbines. The results show that the new DMST formulation demonstrates a better overall performance, compared to the conventional one, when the rotor loading is moderate or high.

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