Flow control on the NREL S809 wind turbine airfoil using vortex generators

Wang, Haipeng; Zhang, Bo; Q, Qiu; Xu, Xiqing

doi:10.1016/j.energy.2016.11.003

Cited by 115 publications

(35 citation statements)

References 27 publications

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“…The bound circulation can now be computed from Eq. (1) as Γ y (4) To fulfill Helmholtz's theorem, vortex filaments with strength equal to the gradient of the bound circulation must be trailed from the trailing edge as dΓ γ y dy (5) where γ is the distribution of bound circulation. However, after some short downstream distance these trailed vortices will curl up to one strong tip vortex with the strength Γ γ y d y dΓ y (6) so that the strength of the trailed vortex simply becomes the integral of the bound circulation from some starting value, hs, to the tip y=h.…”

Section: Estimating the Bound And Trailed Circulation From Cfdmentioning

confidence: 99%

Validation of a Model for Estimating the Strength of a Vortex Created from the Bound Circulation of a Vortex Generator

et al. 2019

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A hypothesis is tested and validated for predicting the vortex strength induced by a vortex generator in wall-bounded flow by combining the knowledge of the Vortex Generator (VG) geometry and the approaching boundary layer velocity distribution. In this paper, the spanwise distribution of bound circulation on the vortex generator is computed from integrating the pressure force along the VG height calculated using CFD. It is then assumed that all this bound circulation is shed into the wake to fulfill Helmholtz's theorem and then curl up into one primary tip vortex. To validate this, the trailed circulation estimated from the distribution of the bound circulation is compared to the one in the wake behind the vortex generator determined directly from the wake velocities at some downstream distance. In practical situations, the pressure distribution on the vane is unknown and consequently other estimates of the spanwise force distribution on the VG must instead be applied, such as using 2D airfoil data corresponding to the VG geometry at each wallnormal distance. Such models have previously been proposed and used as an engineering tool to aid preliminary VG design and it is not the purpose of this paper to refine such engineering models, but to validate their assumptions such as applying a lifting line model on a VG that has a very low aspect ratio and placed in wall boundary layer. Herein, high Reynolds number boundary layer measurements of VG induced flow were used to validate the Reynolds Averaged Navier-Stokes (RANS) modeled circulation results and are used for further illustration and validation of the hypothesis.

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Section: Estimating the Bound And Trailed Circulation From Cfdmentioning

confidence: 99%

Validation of a Model for Estimating the Strength of a Vortex Created from the Bound Circulation of a Vortex Generator

et al. 2019

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“…Flow control technologies, such as VGs [2], plasma flow control [3], microflaps [4], microtabs [5], blowing and suction [6], synthetic jets [7], and flexible walls [8], have been increasingly applied to the design or optimization of wind turbine blades, aiming to improve their aerodynamic performance. Barlas [9] and Johnson [10] compared these flow control methods, while Lin [11] and Wang [12] found that VGs are one of the most effective devices for improving the aerodynamic performance of blades.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the lift coefficient of the double-row VGs could be further improved at high angles of attack due to the different installation positions and sizes. In 2017, Wang et al [12] studied the aerodynamic performance of the S809 airfoil with and without VGs using CFD simulations. The results showed that the VGs can effectively improve the aerodynamic performance of the S809 airfoil, reduce the thickness of the boundary layer, and delay stall.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

Liu

Zhang

et al. 2019

Applied Sciences

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During the operation of wind turbines, flow separation appears at the blade roots, which reduces the aerodynamic efficiency of the wind turbine. In order to effectively apply vortex generators (VGs) to blade flow control, the effect of the VG spacing (λ) on flow control is studied via numerical calculations and wind tunnel experiments. First, the large eddy simulation (LES) method was used to calculate the flow separation in the boundary layer of a flat plate under an adverse pressure gradient. The large-scale coherent structure of the boundary layer separation and its evolution process in the turbulent flow field were analyzed, and the effect of different VG spacings on suppressing the boundary layer separation were compared based on the distance between vortex cores, the fluid kinetic energy in the boundary layer, and the pressure loss coefficient. Then, the DU93-W-210 airfoil was taken as the research object, and wind tunnel experiments were performed to study the effect of the VG spacing on the lift-drag characteristics of the airfoil. It was found that when the VG spacing was λ/H = 5 (H represents the VG's height), the distance between vortex cores and the vortex core radius were approximately equal, which was more beneficial for flow control. The fluid kinetic energy in the boundary layer was basically inversely proportional to the VG spacing. However, if the spacing was too small, the vortex was further away from the wall, which was not conducive to flow control. The wind tunnel experimental results demonstrated that the stall angle-of-attack (AoA) of the airfoil with the VGs increased by 10 • compared to that of the airfoil without VGs. When the VG spacing was λ/H = 5, the maximum lift coefficient of the airfoil with VGs increased by 48.77% compared to that of the airfoil without VGs, the drag coefficient decreased by 83.28%, and the lift-to-drag ratio increased by 821.86%.

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“…Among a number of boundary layer controlling devices such as suction [2,3], blowing [4], synthetic jets [5], vortex generators [6], and riblets [1,[7][8][9][10][11][12], riblets are one of the methodologies used to reduce aircraft surface drag [1,[7][8][9][10][11][12]. Riblets are a passive means of turbulent flow control by which skin friction drag is reduced, and were first employed at the NASA Langley Research Center back in the 1970s [8,13] in imitation of the skin structure of a shark that swims long distances at high speed.…”

Section: Introductionmentioning

confidence: 99%

Interpolation of Turbulent Boundary Layer Profiles Measured in Flight Using Response Surface Methodology

et al. 2018

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Turbulent boundary layer profiles on the aircraft surface were characterized by pitot-rake measurements conducted in flight experiments at high subsonic Mach number ranges. Due to slight variations in atmospheric air conditions or aircraft attitudes, such as angles of attack and absolute flight speeds at different flights even under the same premised flight conditions, the boundary layer profiles measured at different flights can exhibit different shape and velocity values. This concern leads to difficulty in evaluating the efficiency of using some kind of drag-controlling device such as riblets in the flight test, since the evaluation would be conducted by comparing the profiles measured with and without using riblets at different flights. An approach was implemented to interpolate the boundary layer profile for a flight condition of interest based on the response surface method, in order to eliminate the influence of the flight conditional difference. Results showed that the interpolation with the 3rd-degree response surface model with a combination of two independent variables of flight Mach number and total pressure successfully eliminated the influence of the flight conditional difference, and interpolated the boundary layer profiles measured at different flights within an inaccuracy of 4.1% for the flight Mach number range of 0.5 to 0.78.

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Flow control on the NREL S809 wind turbine airfoil using vortex generators

Cited by 115 publications

References 27 publications

Validation of a Model for Estimating the Strength of a Vortex Created from the Bound Circulation of a Vortex Generator

Validation of a Model for Estimating the Strength of a Vortex Created from the Bound Circulation of a Vortex Generator

Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

Interpolation of Turbulent Boundary Layer Profiles Measured in Flight Using Response Surface Methodology

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