Experimental study of the effect of turbulence on horizontal axis wind turbine aerodynamics

Sicot, Christophe; Devinant, Philippe; Laverne, Thomas; Loyer, Stéphane; Hureau, J

doi:10.1002/we.184

Cited by 39 publications

(22 citation statements)

References 14 publications

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“…The pressure measurements of the static airfoil as shown in Figures 4 and 5 are consistent with those of past studies where the lift increases and stall delays with higher FTLs. 7-10 However, similar to what Sicot et al 14 Figure 6 shows the mean velocity fields measured by two-dimensional PIV over the static airfoil at different AOAs and FTLs (0.4%, 4% and 13%). The velocity vectors are set to be uniform, and only every other vector is shown to highlight the recirculation bubbles on the static airfoil's suction surface.…”

Section: Static Pressure Measurementssupporting

confidence: 77%

“…However, similar to what Sicot et al . found that turbulence has little effects on the power and thrust of the wind turbine, the pressures on the suction surface of the rotating blades are shown in Figures and to be little affected by the freestream turbulence up to 13% at AOAs of 11–30°.…”

Section: Resultsmentioning

confidence: 99%

“…This means that the 'local' turbulence intensities along the whole rotating blade are different due to the different rotational speeds at each blade section. However, it is common practice in the past studies 9,14 to take only freestream velocity into account for the study of the effect of freestream turbulence on the wind turbine blade since it is impossible to obtain the same turbulence levels along the wind turbine blade. Therefore, the FTL is used in this study instead of 'local' turbulence level.…”

Section: Turbulence Gridsmentioning

confidence: 99%

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A Tomo‐PIV study of the effects of freestream turbulence on stall delay of the blade of a horizontal‐axis wind turbine

Lee

2014

Wind Energy

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Volumetric velocity fields were measured using tomographic particle image velocimetry on a model of the blade of a 5 kW horizontal‐axis wind turbine to study the effects of freestream turbulence levels (FTLs) at 0.4%, 4% and 13% on stall delay phenomenon at two different global tip speed ratios of 3 and 5 with Reynolds number (Re) ࣈ 5000. Static pressures were measured, and results illustrated that FTL has stronger effect on the surface pressures of the static airfoil. Magnitudes of the absolute velocities within the separated flows above the static airfoil's suction surface increase significantly with higher FTL, while the changes of these velocities above the rotating blade's surface are less obvious. Radial flows from rotating blade's root to tip were also observed with strong spanwise velocity component located in the vicinities of the vortices. At the root and middle sections of the rotating blade, the flows with strong radial velocity component, w, become wider with higher FTL near to the rotating blade's leading edge when the angles of attack (AOAs) are large. At large AOAs, the strength and size of the vortices shed from the rotating blade's leading and trailing edges decrease significantly with higher FTL. However, at small AOAs, the size and coherence of the vortices near the rotating blade's trailing edge increase significantly with higher FTL. Surface streamlines of the rotating blade illustrated that at the rotating blade's root region and at large AOAs, the streamlines tend to lean toward the rotating blade's trailing edge at higher FTL. Copyright © 2014 John Wiley & Sons, Ltd.

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Section: Static Pressure Measurementssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Section: Turbulence Gridsmentioning

confidence: 99%

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A Tomo‐PIV study of the effects of freestream turbulence on stall delay of the blade of a horizontal‐axis wind turbine

Lee

2014

Wind Energy

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“…This is of particular relevance for investigations of the wake of obstacles, e.g., cubes, where the effects of turbulence have been isolated from the effects of shear [27], but there is seemingly no way to perform the opposite investigation. It is also of use to the wind turbine community who have used grids to investigate the influence of free-stream turbulence on wind turbines and blades [36,37,38], and placed wind turbines in boundary layers to produce shear [18,33], but have no way to isolate these parameters in a turbulent shear flow. [27], and (+) Ref.…”

Section: Discussionmentioning

confidence: 99%

Tailoring incoming shear and turbulence profiles for lab‐scale wind turbines

Hearst

Ganapathisubramani

2017

Wind Energy

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An active grid is used to generate a variety of turbulent shear profiles in a wind tunnel. The vertical bars are set to flap through varying angles across the test-section producing a variation in the perceived solidity, resulting in a mean shear. The horizontal bars are used in a fully random operational mode to set the background turbulence level. It is demonstrated that mean velocity profiles with approximately the same shear can be produced with different turbulence intensities and local turbulent Reynolds numbers based on the Taylor microscale, λ. Conversely, it is also demonstrated that flows can be produced with similar turbulence intensity profiles but different mean shear. It is confirmed that the length scales and dynamics, the latter being assessed through the velocity spectra and probability density functions, do not vary significantly across the investigation domain. Such flows are of particular relevance for studies investigating the effect of inflow conditions on obstacles where these studies wish to decouple the effects of turbulence intensity and mean shear, a feat previously unattainable in experimental facilities. Given that the power output of wind turbines is known to be a function of both mean shear and turbulence intensity, the experimental methodology presented herein is invaluable to the wind turbine model testing community who, at present, cannot exert such control authority over the inflow conditions.

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“…The freestream turbulence levels of the atmospheric wind at heights at which wind turbines are normally installed are generally higher compared to the levels achieved in standard wind tunnels. It is known that the airfoil characteristics change with freestream turbulence level [9][10][11][12][13]. Hoffmann [9] studied the effect of varying the freestream turbulence intensity from 0.25% to 9% for NACA0015 airfoil at Re = 250,000 and reported an increase in the peak lift coefficient due to delayed flow separation at higher angles of attack.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Studies on a Low Reynolds Number Airfoil for Wind Turbine Blades

Ahmed

Narayan

Zullah

et al. 2011

JFST

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Testing of a low Reynolds number airfoil designed for low speed horizontal axis wind turbine (HAWT) blades was performed to study its aerodynamic characteristics. Experiments were conducted at Reynolds numbers (Re) of 38,000 to 200,000 at angles of attack from-2 o to 20 o. The airfoil geometry was chosen after testing a number of profiles with XFOIL software. The pressure distribution, lift and drag coefficients and the flow characteristics were also studied with ANSYS-CFX software. The freestream turbulence level was increased from 1% to 5% and 10% which shifted the transition point on the upper surface upstream, resulting in increased skin friction drag for lower angles of attack due to a larger turbulent boundary layer region. The slope of the lift curve did not change much at higher turbulence levels; however, for higher angles of attack, the separation from the upper surface was delayed resulting in an increase in lift and a reduction in drag. The lift to drag ratio increased by 8% to 15% as a result of increasing the turbulence level in the angles of attack-range of interest.

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Experimental study of the effect of turbulence on horizontal axis wind turbine aerodynamics

Cited by 39 publications

References 14 publications

A Tomo‐PIV study of the effects of freestream turbulence on stall delay of the blade of a horizontal‐axis wind turbine

A Tomo‐PIV study of the effects of freestream turbulence on stall delay of the blade of a horizontal‐axis wind turbine

Tailoring incoming shear and turbulence profiles for lab‐scale wind turbines

Experimental and Numerical Studies on a Low Reynolds Number Airfoil for Wind Turbine Blades

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