Wake structure of a single vertical axis wind turbine

Posa, Antonio; Parker, Colin M.; Leftwich, Megan C.; Balaras, Elias

doi:10.1016/j.ijheatfluidflow.2016.02.002

Cited by 75 publications

(40 citation statements)

References 23 publications

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“…Much work, including field-scale measurements [6][7][8][9], laboratory experiments [10][11][12][13][14][15][16][17], and numerical simulations [18][19][20][21][22][23][24][25] has been done recently to study the aerodynamics of VAWTs. In the following, a brief review of the most recent studies related to fluid mechanics of VAWTs is provided.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Abkar

2018

Energies

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In this work, two different theoretical models for predicting the wind velocity downwind of an H-rotor vertical-axis wind turbine are presented. The first model uses mass conservation together with the momentum theory and assumes a top-hat distribution for the wind velocity deficit. The second model considers a two-dimensional Gaussian shape for the velocity defect and satisfies mass continuity and the momentum balance. Both approaches are consistent with the existing and widely-used theoretical wake models for horizontal-axis wind turbines and, thus, can be implemented in the current numerical codes utilized for optimization and real-time applications. To assess and compare the two proposed models, we use large eddy simulation as well as field measurement data of vertical-axis wind turbine wakes. The results show that, although both models are generally capable of predicting the velocity defect, the prediction from the Gaussian-based wake model is more accurate compared to the top-hat counterpart. This is mainly related to the consistency of the assumptions used in the Gaussian-based wake model with the physics of the turbulent wake development downwind of the turbine.

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Section: Introductionmentioning

confidence: 99%

“…They showed that the wake appears to be asymmetric due to the rotation of the blades. Posa et al [13] studied the wake structure of an isolated wind turbine using both particle image velocimetry (PIV) and numerical simulation. They found that the momentum deficit is deflected toward the retreating blade region.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Abkar

2018

Energies

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“…CFD simulation can simulate the whole flow field of a VAWT. In 2016, Posa et al [17] measured the wake structure of a straight-bladed VAWT with double-blades at two different TSRs. They compared the wake distribution by using PIV measurements and Large Eddy Simulation (LES) in a three-dimensional (3D) condition.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Tip Vortex of a Straight-Bladed Vertical Axis Wind Turbine with Double-Blades

et al. 2017

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Abstract:Wind velocity distribution and the vortex around the wind turbine present a significant challenge in the development of straight-bladed vertical axis wind turbines (VAWTs). This paper is intended to investigate influence of tip vortex on wind turbine wake by Computational Fluid Dynamics (CFD) simulations. In this study, the number of blades is two and the airfoil is a NACA0021 with chord length of c = 0.265 m. To capture the tip vortex characteristics, the velocity fields are investigated by the Q-criterion iso-surface (Q = 100) with shear-stress transport (SST) k-ω turbulence model at different tip speed ratios (TSRs). Then, mean velocity, velocity deficit and torque coefficient acting on the blade in the different spanwise positions are compared. The wind velocities obtained by CFD simulations are also compared with the experimental data from wind tunnel experiments. As a result, we can state that the wind velocity curves calculated by CFD simulations are consistent with Laser Doppler Velocity (LDV) measurements. The distribution of the vortex structure along the spanwise direction is more complex at a lower TSR and the tip vortex has a longer dissipation distance at a high TSR. In addition, the mean wind velocity shows a large value near the blade tip and a small value near the blade due to the vortex effect.

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“…Posa et al [19] investigated the wake of an isolated vertical axis wind turbine using large-eddy simulations. A filteredstructure fonction model and immersed boundary method was used.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulations on Vertical Axis Hydrokinetic Turbines - Power coefficient analysis for various solidities

et al. 2020

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Large Eddy Simulations (LES) are performed on a Vertical Axis Hydrokinetic Turbine (VAHT) at two different solidities, so as to enable a more complete physical description of the flow than for classic statistical calculations. To analyze the turbine performances, local quantities are defined to evaluate the contribution of the different turbine elements to the global VAHT power coefficient. For a deeper analysis of the major losses, the real turbine is also compared with an ideal turbine composed of only three infinite blades. It is observed that the ideal turbine with the lower solidity provides the best performance, but the losses due to the blade tips and the arms strongly increase for the real turbine at the same solidity. Consequently, for the considered real turbine, there is no clear gain to decrease the solidity. Simulations of the ideal turbine are performed for various solidities at their optimal Tip Speed Ratio (TSR) to study the evolution of optimal power coefficient as a function of solidity. A maximum power coefficient is obtained for a small value of the solidity. This is explained because the optimal TSR of this optimal solidity leads to angles of incidences on the blade which avoid a penalizing dynamic stall phenomenon but are high enough to produce an important positive torque The design of an efficient turbine has then to limit losses, to be able to use small solidity and then to avoid dynamic stall phenomenon by having a high optimal TSR.

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Wake structure of a single vertical axis wind turbine

Cited by 75 publications

References 23 publications

Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Numerical Investigation of the Tip Vortex of a Straight-Bladed Vertical Axis Wind Turbine with Double-Blades

Large Eddy Simulations on Vertical Axis Hydrokinetic Turbines - Power coefficient analysis for various solidities

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