On the use of Gurney Flaps for the aerodynamic performance augmentation of Darrieus wind turbines

Bianchini, Alessandro; Balduzzi, Francesco; Rosa, Daniele Di; Ferrara, Giovanni

doi:10.1016/j.enconman.2019.01.068

Cited by 88 publications

(43 citation statements)

References 54 publications

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“…To meet the objectives described above, the use of computational fluid dynamics (CFD) is mandatory. Due to the complex flow structures taking place behind the GF, the continuous variation of the AoA, and the existence of large separated regions when the stall appears, the simpler modeling methods (e.g., a panel method) are insufficient for this scope [6,15]. In order to limit the computational cost, the unsteady Reynolds-averaged formulation of the Navier-Stokes equations (URANS approach) is used for the presented analyses as the best compromise.…”

Section: Objectivesmentioning

confidence: 99%

“…Due to the wide range of spatial and temporal scales that need to be captured in the flow features in the presented problem, more accurate methods addressing the turbulent flows such as direct numerical simulation (DNS) or large eddy simulation (LES) would be in fact unusable. In addition, recent examples in the literature showed that the proposed approach is able to properly capture all the effects connected to the use of GFs [6]. A key original model developed for the study presented in this paper is represented by the definition of AoA variations that match exactly the functioning conditions in a broad range of Darrieus VAWTs.…”

Section: Objectivesmentioning

confidence: 99%

“…Among different approaches to reach this scope, lately increasing attention is given to the possibility of applying passive flow control devices to Darrieus blades [6], in order to delay the onset of stalls and improve the lift-to-drag ratio, especially at medium-low Reynolds numbers. Gurney flaps (GFs) are one of the technologies in the spotlight.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis on the Effectiveness of Gurney Flaps as Power Augmentation Devices for Airfoils Subject to a Continuous Variation of the Angle of Attack by Use of Full and Surrogate Models

et al. 2020

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The disclosing of new diffusion frontiers for wind energy, like deep-water offshore applications or installations in urban environments, is putting new focus on Darrieus vertical-axis wind turbines (VAWTs). To partially fill the efficiency gap of these turbines, aerodynamic developments are still needed. This work in particular focuses on the development of a mathematical model that allows predicting the possible performance improvements enabled in a VAWT by application of the Gurney flaps (GFs) as a function of the blade thickness, the rotor solidity and geometry of the Gurney flap itself. The performance of airfoil with GFs was evaluated by means of detailed simulations making use of computational fluid dynamics (CFD). The accuracy of the CFD model was assessed against the results of a dedicated experimental study. In the simulations, a dedicated method to simulate cycles of variation of the angle of attack similar to those taking place in a cycloidal motion (rather than purely sinusoidal ones) was also developed. Based on the results from CFD, a multidimensional interpolation based on the radial basis functions was conducted in order to find the GF design solution that provides the highest efficiency for a given turbine in terms of airfoil and solidity. The results showed that, for the selected study cases based on symmetric airfoils, the GF positioned facing outwards from the turbine, which provides the upwind part of the revolution, can lead to power increments ranging from approximately 30% for the lower-solidity turbine up to 90% for the higher-solidity turbine. It was also shown that the introduction of a GF should be coupled with a re-optimization of the airfoil thickness to maximize the performance.

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Section: Objectivesmentioning

confidence: 99%

Section: Objectivesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis on the Effectiveness of Gurney Flaps as Power Augmentation Devices for Airfoils Subject to a Continuous Variation of the Angle of Attack by Use of Full and Surrogate Models

et al. 2020

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“…In addition, other flap structures have also been used by different scholars to reduce the loads of the blades and enhance the aerodynamic performance. For example, a gurney flap (GF) placed at the pressure side of the trailing edge of an airfoil and perpendicular to the chord line can enhance lift in wind turbine blades and enhance the aerodynamic performance of airfoils, making it generate more Energies 2020, 13, 1029 3 of 21 lift and delaying the onset of stall [16][17][18]. Bianchini presented numerical analysis using CFD with the aim of evaluating the potential of using GFs for the power augmentation of Darrieus turbines [16].…”

Section: Introductionmentioning

confidence: 99%

“…For example, a gurney flap (GF) placed at the pressure side of the trailing edge of an airfoil and perpendicular to the chord line can enhance lift in wind turbine blades and enhance the aerodynamic performance of airfoils, making it generate more Energies 2020, 13, 1029 3 of 21 lift and delaying the onset of stall [16][17][18]. Bianchini presented numerical analysis using CFD with the aim of evaluating the potential of using GFs for the power augmentation of Darrieus turbines [16]. Zhang et al presented a computational investigation on the effects of two configurations of GFs on the aerodynamic performance with the computational method applied in the investigation solving the Reynold-averaged NSE with a multiple reference frame approach, which models the rotating turbulent flow over the rotor [17].…”

Section: Introductionmentioning

confidence: 99%

Sliding Mode Control of Active Trailing-Edge Flap Based on Adaptive Reaching Law and Minimum Parameter Learning of Neural Networks

et al. 2020

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Theoretical modeling and the sliding mode control (SMC) of an active trailing-edge flap of a wind turbine blade based on the adaptive reaching law are investigated. The blade is a single-celled thin-walled composite structure using circumferentially asymmetric stiffness (CAS) design, exhibiting displacements of flap-wise/twist coupling. A reduced structural model originated from the variation method is used to model the structure of the blade, the structural damping of which is computed. The trailing-edge flap is a rigid structure that is embedded in and hinged to the blade host structure, and it is driven by two pairs of pneumatic cylinders moving in reverse. Flutter suppression for the large-amplitude vibration of the blade tip is investigated based on an active trailing-edge flap structure and SMC algorithm using the adaptive reaching law. The controlled responses of flap-wise/twist displacements and control inputs (the angles of the trailing-edge flap) are illustrated, with obvious simulation effects demonstrated. An experimental platform for driving the pneumatic cylinders verifies the effectiveness of the control algorithm using the adaptive reaching law and the effectiveness of the selected pneumatic transmission scheme controlled by another adaptive SMC based on the minimum parameter learning of neural networks.

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A review on the use of passive flow control devices as performance enhancement of lift‐type vertical axis wind turbines

Syawitri

Yao

et al. 2022

WIREs Energy & Environment

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This article provides a comprehensive review about passive flow control devices (PFCDs) implemented in lift‐type vertical axis wind turbine (LVAWT), focusing on the underlying flow physics mechanisms and to what extents they can improve the LVAWT performance. In addition, some novel concepts that can be potentially implemented in future are also presented. Based on literature review, it is observed that PFCDs can enhance the power generation of LVAWT up to 172.73% compared with a clean LVAWT. However, this significant improvement still needs to be evaluated carefully by considering the economic feasibility aspect, because PCFDs can increase the design complexity, weight penalty and manufacturing cost of LVAWT. Furthermore, it is essential to design and evaluate the effectiveness of PFCDs using a full VAWT configuration by considering the blade rotating effects and blade‐to‐blade interactions. Finally, evaluation of PFCDs needs to be performed at all ranges of tip speed ratios (TSRs) operation conditions, as there are clear evidences on the correlation between LVAWT performance and different range of TSRs. This article is categorized under: Sustainable Energy > Wind Energy

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On the use of Gurney Flaps for the aerodynamic performance augmentation of Darrieus wind turbines

Cited by 88 publications

References 54 publications

Numerical Analysis on the Effectiveness of Gurney Flaps as Power Augmentation Devices for Airfoils Subject to a Continuous Variation of the Angle of Attack by Use of Full and Surrogate Models

Numerical Analysis on the Effectiveness of Gurney Flaps as Power Augmentation Devices for Airfoils Subject to a Continuous Variation of the Angle of Attack by Use of Full and Surrogate Models

Sliding Mode Control of Active Trailing-Edge Flap Based on Adaptive Reaching Law and Minimum Parameter Learning of Neural Networks

A review on the use of passive flow control devices as performance enhancement of lift‐type vertical axis wind turbines

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