Analysis of the effect of freestream turbulence on dynamic stall of wind turbine blades

Huang, Xianfu; Albers, Marian; Meysonnat, Pascal S.; Meinke, Matthias; Schröder, Wolfgang

doi:10.1016/j.ijheatfluidflow.2020.108668

Cited by 17 publications

(30 citation statements)

References 38 publications

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“…Ravi et al 2012). These are also well within the capability of supercomputers using a numerical approach (Kim & Xie 2016;Huang et al 2020). On the other hand, a study of large-scale FST (e.g.…”

Section: Introductionmentioning

confidence: 60%

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Impact of large-scale free-stream turbulence on a pitching airfoil

Boye,

Djidjeli,

Xie

2024

Flow

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This paper investigates the impact of large-scale turbulence on the aerodynamic characteristics of a pitching wind turbine blade at Reynolds number 135 000, whose cross-section is a NACA0012 airfoil with constant chord length. Large-eddy simulations at reduced frequencies, $k_{red} = 0.05$ and 0.1, were validated against reference data from the literature. An efficient method capable of generating synthetic large-scale turbulence at the inlet was applied by using two streamwise integral length scales $L_{x} = 1c$ and 1.5 $c$ , which represent energetic turbulence eddies at the height where the wind turbine operates. For $k_{red}= 0.1$ , the change in the maximum lift coefficient at the dynamic stall angle near the maximum angle of attack is on average 20 % lower and during the downstroke it is on average 22 % lower, compared with the smooth inflow. A higher reduced frequency ( $k_{red} = 0.2$ ) apparently does not further change the lift, drag and moment coefficients, and the inflow turbulence disordered leading-edge vortices. The turbulent shear stress and the phase-averaged dispersive shear stress in the wake are of the same magnitude, but with negative and positive signs, respectively, suggesting that the large-scale phase-averaged fluctuations transfer momentum in the opposite direction compared with the turbulent fluctuations, reducing the drag on the suction-side flow, and subsequently increasing the averaged lift coefficient. This demonstrates the critical importance of the large-scale non-turbulent unsteadiness in the wake of a pitching wing.

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Section: Introductionmentioning

confidence: 60%

“…Lau, Haeri & Kim 2013;Bowen, Celik & Azarpeyvand 2023) and wind engineering (e.g. Kim & Xie 2016;Huang et al 2020;Boye 2022) areas.…”

Section: Introductionmentioning

confidence: 99%

Impact of large-scale free-stream turbulence on a pitching airfoil

Boye,

Djidjeli,

Xie

2024

Flow

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“…The Clark-Y airfoil design was widely used for aircraft design, 32 but is still used for wind turbine applications. [33][34][35] A slightly modified version of the Clark-Y airfoil design was also used for a medium-size research wind turbine, which was a part of the research project DFG PAK 780. 36 The dimensions of the Clark-Y shaped blade (blade B) are shown in Figure 5.…”

Section: Blade A: Naca 4412 Shapementioning

confidence: 99%

“…The Clark-Y airfoil was used due its low sensitivity to Reynolds number effects. 35 Aerodynamic properties for Reynolds numbers from 0:5 Á 10 5 to 3 Á 10 5 were measured for the Clark-Y by Marchman et al 37 It is shown, that the airfoil has a good aerodynamic performance and improved lift-to-drag-ratio for a Reynolds number down to 0:5 Á 10 5 . That is mainly related to the flat bottom side of the profile.…”

Section: Blade A: Naca 4412 Shapementioning

confidence: 99%

Localization of wind turbine noise using a microphone array in wind tunnel measurements

Ocker

Blumendeller²,

Berlinger³

et al. 2021

Wind Energy

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An experimental investigation on scaled wind turbine models in a wind tunnel with a microphone array is presented. Our study focuses on the localization and quantification of aerodynamic noise sources on rotating wind turbine blades with the aim of identifying the contributing factors that have an impact on the source spectra. Therefore, wind tunnel measurements were conducted for three different blade geometries (NACA 4412 shape, Clark-Y shape, and sickle shape), five pitch angles between À2 and +8 and five wind velocities between 5 and 13 ms ^À1 . For the localization of rotating sound sources with a microphone array, a rotating beamforming method based on the acoustic ray method is used. The Clean-SC deconvolution method was used to improve the resolution of the acoustic sources, and integrated spectra were calculated for the individual blades. The sound sources were localized at the wind turbine blades and assigned to the leading edge and trailing edge subregions. The results show a high dependency on the sound source distribution and the source strength with regard to the observed one-third octave bands, wind velocity, and blade geometry. Hence, the localization of rotating sound sources with a microphone array is a suitable method for the development of wind turbine blades that emit less noise.

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“…They found that rotational augmentation delayed the onset of dynamic stall. Huang et al (5) analyzed the effect of free-stream turbulence on the dynamic stall of wind turbine blades and found that the freestream turbulence in a turbulent flow at a turbulence level of 5% helped improve the aerodynamic performance of the wind turbine blade. Zhu et al (6) introduced passive vortex generators (VGs) on wind turbine airfoils to delay the onset of static stall and improve the aerodynamic performance.…”

Section: Introductionmentioning

confidence: 99%

Influence of Oscillation Frequency and Nonlinear Structural Material of Airfoil in Wind Turbine System During Dynamic Stall

Wang¹,

Mishra²

2021

Sensors and Materials

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We study the nonlinear behavior of a wind turbine airfoil oscillating along the pitch mode of oscillation. In the analysis, the nonlinearity of the structural material, the airspeed, and the reduced frequency of oscillation are the important parameters considered. The equation of motion for the pitching oscillation case is modeled and derived using the Office National d'Etudes et de Recherches Aérospatiales (ONERA) dynamic stall model. In the ONERA dynamic stall model, the aerodynamic loads are given in terms of differential equations. We focus on the influence of the material structural nonlinearity and nondimensional airspeed on the wind turbine airfoil during the pitch mode of oscillation. The type of airfoil considered is the National Advisory Committee for Aeronautics (NACA) 0012 airfoil. To understand the effects of dynamic stall on the system under different situations of structural nonlinearity, we use bifurcation plots, phase plots, Poincaré maps, and the maximum Lyapunov exponent (MLE) to analyze the behavior of the airfoil and avoid the effect of non-periodic motion of the airfoil on the wind turbine system. The results show that chaos occurs for specific parameters of the airfoil of the wind turbine, which can be avoided by avoiding certain operating conditions corresponding to chaotic motion. This finding can be used as a guideline for wind turbine design and decrease the cost of maintenance.

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Analysis of the effect of freestream turbulence on dynamic stall of wind turbine blades

Cited by 17 publications

References 38 publications

Impact of large-scale free-stream turbulence on a pitching airfoil

Impact of large-scale free-stream turbulence on a pitching airfoil

Localization of wind turbine noise using a microphone array in wind tunnel measurements

Influence of Oscillation Frequency and Nonlinear Structural Material of Airfoil in Wind Turbine System During Dynamic Stall

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