Flow Physics and Performance of Vertical Axis Wind Turbine Arrays

Duraisamy, Karthik; Lakshminarayan, Vinod K.

doi:10.2514/6.2014-3139

Cited by 15 publications

(11 citation statements)

References 10 publications

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“…[11] numerically showed that a pair of rotating VAWT cross sections exhibit wake suppression behavior similar to that observed by Chan et al [3] for a pair of rotating cylinder cross sections. The study by Duraisamy and Lakshminarayan [11] also began looking at the interaction between larger numbers of turbine cross sections, arranged in up to five infinite-extent rows. The interactions between turbines were observed to create regions of high momentum and also shifted regions of low-momentum wake deficits.…”

Section: Introductionsupporting

confidence: 77%

A Kinematic Description of the Key Flow Characteristics in an Array of Finite-Height Rotating Cylinders

Craig

Dabiri

Koseff

2016

Journal of Fluids Engineering

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Experimental data are presented for large arrays of rotating, finite-height cylinders to study the dependence of the three-dimensional (3D) mean flows on the geometric and rotational configurations of the array. Two geometric configurations, each with two rotational configurations, were examined at a nominal Reynolds number of 600 and nominal tip-speed ratios of 0, 2, and 4. It was found that the rotation of the cylinders drives the formation of streamwise and transverse flow patterns between cylinders and that net time–space averaged transverse and vertical flows exist within the developed flow region of the array. This net vertical mean flow provides an additional mechanism for the exchange of momentum between the flow within the array and the flow above it, independent from the turbulent exchange mechanisms which are also observed to increase by almost a factor of three in a rotating array. As an array of rotating cylinders may provide insight into the flow kinematics of an array of vertical axis wind turbines (VAWTs), this planform momentum flux (both mean and turbulent) is of particular interest, as it has the potential to increase the energy resource available to turbines far downstream of the leading edge of the array. In the present study, the streamwise momentum flux into the array could be increased for the rotating-element arrays by up to a factor of 5.7 compared to the stationary-element arrays, while the streamwise flow frontally averaged over the elements could be increased by up to a factor of four in the rotating-element arrays compared to stationary-element arrays.

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Section: Introductionsupporting

confidence: 77%

A Kinematic Description of the Key Flow Characteristics in an Array of Finite-Height Rotating Cylinders

Craig

Dabiri

Koseff

2016

Journal of Fluids Engineering

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“…The positive effects on the power coefficient have been confirmed numerically by Duraisamy and Lakshminarayan [10], Zanforlin and Nishino [11] and Parneix et al [12].…”

Section: Introductionmentioning

confidence: 60%

“…To the authors' knowledge, the only wind tunnel study that exists for multiple VAWTs (arrays of two and three turbines) is by Ahmadi-Baloutaki et al [25]. However, these turbines had a very high solidity and were spaced well apart (2 diameters shaft to shaft), so the results are difficult to compare with the numerical studies available [10,11]. Therefore, the main focus of this article is on wind tunnel experiments of a pair of counterrotating H-type Darrieus VAWTs at very small inter-turbine distances (1.2 and 1.3 diameters shaft to shaft), to validate the power enhancement predicted by the numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Experimental validation of the power enhancement of a pair of vertical-axis wind turbines

et al. 2020

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Wind tunnel tests have been performed of individual and paired H-type Darrieus vertical-axis wind turbines. The turbines in the paired configuration are closely spaced, at 1.2 and 1.3 rotor diameters shaft to shaft, and are counter-rotating. Two directions of rotation were studied, one where the facing (inner) blades move along with the incoming flow, and one where the facing blades move against the wind. The wind tunnel tests confirm a net increase in the power coefficient of the paired configuration compared with twice the power coefficient of the individual turbine. We found average relative increases in the power coefficients between 13 % and 16 %, which is consistent with numerical studies available in the literature.

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“…Ferreira et al [17] simulated dynamic stall in a section of a VAWT using detached-eddy simulation at Re 50;000 and validated the results by comparing the vorticity in the rotor area with particle image velocimetry (PIV) data. Duraisamy and Lakshminarayan [18] numerically analyzed interactions of VAWTs with various configurations using RANS at Re 67;000. Barsky et al [19] investigated the fundamental wake structure of a single VAWT computationally by large-eddy simulation and experimentally by PIV.…”

mentioning

confidence: 99%

Coriolis Effect on Dynamic Stall in a Vertical Axis Wind Turbine

Tsai

Colonius

2016

AIAA Journal

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The immersed boundary method is used to simulate the flow around a two-dimensional cross section of a rotating NACA 0018 airfoil in order to investigate the dynamic stall occurring on a vertical axis wind turbine. The influence of dynamic stall on the force is characterized as a function of tip-speed ratio and Rossby number. The influence of the Coriolis effect is isolated by comparing the rotating airfoil to one undergoing an equivalent planar motion that is composed of surging and pitching motions that produce an equivalent speed and angle-of-attack variation over the cycle. Planar motions consisting of sinusoidally varying pitch and surge are also examined. At lower tip-speed ratios, the Coriolis force leads to the capture of a vortex pair when the angle of attack of a rotating airfoil begins to decrease in the upwind half cycle. This wake-capturing phenomenon leads to a significant decrease in lift during the downstroke phase. The appearance of this feature depends subtly on the tip-speed ratio. On the one hand, it is strengthened due to the intensifying Coriolis force, but on the other hand, it is attenuated because of the comitant decrease in angle of attack. While the present results are restricted to two-dimensional flow at low Reynolds numbers, they compare favorably with experimental observations at much higher Reynolds numbers. Moreover, the wake-capturing is observed only when the combination of surging, pitching, and Coriolis force is present.

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Flow Physics and Performance of Vertical Axis Wind Turbine Arrays

Cited by 15 publications

References 10 publications

A Kinematic Description of the Key Flow Characteristics in an Array of Finite-Height Rotating Cylinders

A Kinematic Description of the Key Flow Characteristics in an Array of Finite-Height Rotating Cylinders

Experimental validation of the power enhancement of a pair of vertical-axis wind turbines

Coriolis Effect on Dynamic Stall in a Vertical Axis Wind Turbine

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