Numerical analysis of the effect of flaps on the tip vortex of a wind turbine blade

Huang, Xianfu; Moghadam, Seyed Mohsen Alavi; Meysonnat, Pascal S.; Meinke, Matthias; Schröder, Wolfgang

doi:10.1016/j.ijheatfluidflow.2019.05.004

Cited by 21 publications

(11 citation statements)

References 29 publications

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“…Active techniques such as the use of flaps have also been considered. 12,13 Such techniques are not always successful and it appears that a more detailed understanding of the vortex roll-up process and near-field dynamics is needed to make consistent improvements across a broader range of operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Wing-tip vortex dynamics at moderate Reynolds numbers

Smith

Ventikos

2021

Physics of Fluids

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The flow over a flat-tipped wing at three Reynolds numbers: Re ¼ 1 Â 10 4 ; Re ¼ 4 Â 10 4 , and Re ¼ 1 Â 10 5 is investigated using direct numerical simulation. A set of grid independent results are obtained which allow for the dynamics of the tip flow, trailing vortices, and their interplay with the boundary layer dynamics to be examined in detail. The results show significant changes across the Reynolds number range. At the lowest Reynolds number, a single trailing vortex forms downstream of the trailing edge, whereas multiple vortices form over the tip at higher Reynolds numbers. The tip geometry is shown to be important with regard to the development of different structures and in the transition of the flow from laminar to turbulent. This is due to unstable shear layers, with turbulent flow becoming entrained in the vortex cores at higher Reynolds numbers. These changing vortex dynamics mean that the value of the minimum vortex core pressure and its location change with Reynolds number. This has important consequences for cavitation inception and scaling for hydrodynamic applications. The influence of the tip flow on the boundary layer is further considered by comparing the flow with that of an infinite-span wing. Analysis of the two cases shows that the tip flow reduces the effective angle of attack, which prevents the flow separation at the leading edge that is responsible for the boundary layer transition for the infinite-span case. This, in turn, changes the character of the trailing edge flow which would have significant consequences on the trailing edge noise.

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Section: Introductionmentioning

confidence: 99%

Wing-tip vortex dynamics at moderate Reynolds numbers

Smith

Ventikos

2021

Physics of Fluids

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“…(2) The aeroelastic equation of Equations (12) to (13) is modeled in mATLAB environment in a computer. The two adaptive SMC algorithms mentioned above run completely in PLC hardware.…”

Section: Experimental Platform Based On Pneumatic Transmission and Comentioning

confidence: 99%

“…Qin and Chen reported an investigation into the performance of trailing-edge flow control devices, including microtabs and microjets installed (near the trailing edge) by solving the three-dimensional Reynolds averaged Navier-Stokes equations (NSE) [12]. Huang et al used the trailing-edge flap and mid-span flap (deflected in opposite directions such that the root bending moment of the blade remains almost unchanged) to excite the unstable modes of the tip vortex system of blades to investigate the mechanism of how and to what extent the deflection of the flaps influences the tip vortex system [13]. Thakur et al investigated the load mitigation effects using blade trailing-edge flaps subjected to turbulent wind, with the BEM theory used to obtain the aerodynamic loads by modeling in a multi-body framework while the hydrodynamic and geotechnical analysis were performed in a FEM framework [14].…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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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“…In recent years, the local TEF structures including mid-span flap (Huang et al 13 ) and gurney flap (Bianchini et al 14 ), have been used by different scholars to reduce the loads of blades and enhance the aerodynamic performance, with Blade Element Momentum theory or CFD theory used to compute the aerodynamic loads. In the present study, a 3D composite cantilever blade exhibiting flap-wise bending and twist displacements uses CAS configuration by skewing angle-plies with respect to the blade axis in the top flange (above the chord) and the bottom flange, so as to realize structural modeling.…”

Section: Introductionmentioning

confidence: 99%

Vibration control of cantilever blade based on trailing-edge flap by restricted control input

Liu

Gong

2021

Measurement and Control

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Vibration and control of cantilever blade with bending-twist coupling (BTC) based on trailing-edge flap (TEF) by restricted control input are investigated. The blade is a thin-walled structure using circumferentially asymmetric stiffness (CAS) configuration, with TEF embedded and hinged into the host composite structure along the entire blade span. The TEF structure is driven by quasi-steady aerodynamic forces. Vibration control is investigated based on linear matrix inequation (LMI) algorithm using restricted control input (LMI/RCI). Flutter suppression of BTC displacements and the angle of TEF (i.e. the practical control input) are illustrated, with apparently controlled effects demonstrated. The restricted control input signals are used to driven the TEF to explore the scope of the feasibility of the practical TEF angle, which is displayed by a virtual simulation platform. The platform verifies the feasibility of the hardware implementation for the control algorithms.

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Numerical analysis of the effect of flaps on the tip vortex of a wind turbine blade

Cited by 21 publications

References 29 publications

Wing-tip vortex dynamics at moderate Reynolds numbers

Wing-tip vortex dynamics at moderate Reynolds numbers

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

Vibration control of cantilever blade based on trailing-edge flap by restricted control input

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