Study of wake characteristics of a vertical axis wind turbine by two- and three-dimensional computational fluid dynamics simulations

Lam, Heung-Fai; Peng, HY

doi:10.1016/j.renene.2016.01.011

Cited by 159 publications

(93 citation statements)

References 22 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%

“…They showed that LES coupled with an actuator-line model can yield accurate predictions of the mean and higher-order statistics in the wake. Lam and Peng [20] used a blade-resolving numerical technique to study the near and far-wake regions of a straight-bladed VAWT. They showed that the asymmetry of the wake increases as the wake is advected downstream.…”

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%

Section: Introductionmentioning

confidence: 99%

Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Abkar

2018

Energies

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“…With the aim of constructing a high-fidelity simulation tool for VAWTs, the formulation of a 3D CFD model causing technically-acceptable computational costs still remains a relevant challenge.To the authors' best knowledge, only few 3D studies have been published on VAWT simulations. 3D URANS results of VAWT in skewed flows are presented in [11], 2D and 3D models are applied in [3] for aerodynamic modeling, and in [12] to investigate the self-starting capability of VAWT. The most advanced attempt of a fully 3D simulation of a VAWT is reported in [13], where a single-blade configuration was considered due to restrictions in computational cost.The present paper shows how a proper computational set-up allows obtaining reliable three-dimensional prediction of the flow around the rotor, of the wake, and of the turbine performance, at a reasonable (namely, industrially affordable) computational cost.…”

mentioning

confidence: 99%

“…To the authors' best knowledge, only few 3D studies have been published on VAWT simulations. 3D URANS results of VAWT in skewed flows are presented in [11], 2D and 3D models are applied in [3] for aerodynamic modeling, and in [12] to investigate the self-starting capability of VAWT. The most advanced attempt of a fully 3D simulation of a VAWT is reported in [13], where a single-blade configuration was considered due to restrictions in computational cost.…”

mentioning

confidence: 99%

Three-Dimensional CFD Simulation and Experimental Assessment of the Performance of a H-Shape Vertical-Axis Wind Turbine at Design and Off-Design Conditions

Franchina

Kouaissah

Persico

et al. 2019

IJTPP

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The paper presents the results of a computational study on the aerodynamics and the performance of a small-scale Vertical-Axis Wind Turbine (VAWT) for distributed micro-generation. The complexity of VAWT aerodynamics, which are inherently unsteady and three-dimensional, makes high-fidelity flow models extremely demanding in terms of computational cost, limiting the analysis to mainly 2D or 2.5D Computational Fluid-Dynamics (CFD) approaches. This paper discusses how a proper setting of the computational model opens the way for carrying out fully 3D unsteady CFD simulations of a VAWT. Key aspects of the flow model and of the numerical solution are discussed, in view of limiting the computational cost while maintaining the reliability of the predictions. A set of operating conditions is considered, in terms of tip-speed-ratio (TSR), covering both peak efficiency condition as well as off-design operation. The fidelity of the numerical predictions is assessed via a systematic comparison with the experimental benchmark data available for this turbine, consisting of both performance and wake measurements carried out in the large-scale wind tunnel of the Politecnico di Milano. The analysis of the flow field on the equatorial plane allows highlighting its time-dependent evolution, with the aim of identifying both the periodic flow structures and the onset of dynamic stall. The full three-dimensional character of the computations allows investigating the aerodynamics of the struts and the evolution of the trailing vorticity at the tip of the blades, eventually resulting in periodic large-scale vortices. technology dominates the market today but, in the aforementioned non-conventional environments, the Vertical-Axis Wind Turbine (VAWT) can be an interesting alternative, for several reasons: it is inherently 'aerodynamically' robust to yawed and skewed flows; it can provide a proper structural coupling with floating foundations (as demonstrated in the frame of the DeepWind EU program, [1]); it is characterized by lower costs of installation and maintenance as the gearbox and the generator can be placed on the ground; it produces lower acoustic pollution due to the lower optimal tip speed ratio with respect to HAWT. However, VAWT rotors are characterized by very complex aerodynamics, inherently unsteady, and fully three-dimensional, resulting in periodic fluctuating forces which ultimately complicate the structural design and affect the turbine performance.Several engineering methods were specifically developed for VAWTs, such as the multiple stream-tube and the double multiple stream-tube, that are analyzed in detail in [2]. In recent years, higher fidelity methods based on Computational Fluid Dynamics (CFD) have been applied to VAWTs, obtaining physically-sound representations of the flow field around the rotor [3-7], as well as quantitatively reliable performance estimates [8]. However, such simulations cause very high computational cost that has historically led the researchers to employ simplified actuator-line [9] or 2D...

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“…This can properly treat complex flows and the boundary layer effects near the rotor blade [21]. Apart from the numerical scheme, grid deployment plays another important role in the production of valid numerical results [22]. In the present study, for all numerical cases, the equiangle skewness of the grids ranges from 0.2 to 0.28; the values of y+ range from 27 to 61.…”

Section: Introductionmentioning

confidence: 96%

Upstream Flow Control for the Savonius Rotor under Various Operation Conditions

et al. 2018

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Applications of the Savonius rotor have been extended in recent years, necessitating an in-depth investigation on flow characteristics of such a fluid energy converting device. For the wake flow downstream of the Savonius rotor, studies have been reported extensively. Nevertheless, literature specifically devoted to the upstream flow of the Savonius rotor can rarely be found. This review collects and compiles findings from relevant studies to prove the significance of upstream flow patterns to the operation of the Savonius rotor. Then attempts from experimental and numerical aspects to substantiate the important effect of the upstream flow are implemented. Based on practical cases and laboratory works, upstream flow patterns for the Savonius rotor are divided into four types, namely uniform flow, guided flow, rotor wake flow and oscillating flow. Accordingly, conditions under which these upstream flow patterns arise are analyzed respectively. Experimental and numerical results are presented to clarify the influential factors underlying diverse upstream flow patterns. Furthermore, the relationship between the performance of the Savonius and the upstream flow is elucidated, facilitating the development of techniques of controlling the upstream flow. This review provides a systematic reference for the control of the upstream flow for the Savonius rotor, which has the tendency of developing into an independent technical branch.

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Study of wake characteristics of a vertical axis wind turbine by two- and three-dimensional computational fluid dynamics simulations

Cited by 159 publications

References 22 publications

Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Theoretical Modeling of Vertical-Axis Wind Turbine Wakes

Three-Dimensional CFD Simulation and Experimental Assessment of the Performance of a H-Shape Vertical-Axis Wind Turbine at Design and Off-Design Conditions

Upstream Flow Control for the Savonius Rotor under Various Operation Conditions

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