Parametric Investigation of Gurney Flaps for the Use on Wind Turbine Blades

Alber, Joerg; Pechlivanoglou, George; Paschereit, Christian Oliver; Twele, Jochen; Weinzierl, Guido

doi:10.1115/gt2017-64475

Cited by 11 publications

(12 citation statements)

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“…2b: for GF = 1.5 %c a vortex street is triggered, while for GF = 0.5 %c the wake is shed in a relatively smooth way. In a similar manner, Alber et al (2017) suggest the use of very small GF heights of approximately half the local BL thickness in order to maintain, or even improve, the airfoil L / D ratio of different DU and NACA airfoils.…”

Section: Introductionmentioning

confidence: 91%

“…Additionally, another GF height of half the local δ is chosen so that the GF configurations consist of GF = 1.0 %c and GF = 0.5 %c. For comparison, the FFA-W3-241 airfoil (th max = 24.1 %c, Re = 12.0 × 10 6 ), which is used in the outer blade region of the DTU 10 MW reference wind turbine (Bak et al, 2013), generates a BL of δ TE ≈ 0.30 %c. As such, the application of GF > 0.30 %c would be likely to cause the L / D ratio to decline, as illustrated in Fig.…”

Section: Gurney Flapsmentioning

confidence: 99%

“…More recently, Vestas ® has started offering GFs in combination with VGs as so-called aerodynamic upgrades of HAWTs, predicting annual yield improvements of up to 2.0 % (Vestas, 2020). The design of the DTU 10 MW reference wind turbine includes smooth wedge-shaped GFs in the first half of the blade length, 0.05R < r < 0.4R, using GF heights in the range of 1.3 %c < GF < 3.5 %c (Bak et al, 2013). Figure 2b illustrates the changes in the flow field of the laminar airfoil HQ17 when implementing different GF heights, as reported by Liebeck (1978) by means of the Newman airfoil.…”

Section: Introductionmentioning

confidence: 99%

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Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

et al. 2020

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Abstract. This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 m, and the blade configurations consist of the clean and the tripped baseline cases, emulating the effects of forced leading-edge transition. The wind tunnel experiments include three operation points based on tip speed ratios of 3.0, 4.3, and 5.6, reaching Reynolds numbers of approximately 2.5×105. The measurements are taken by means of three different methods: ultrasonic anemometry in the wake, surface pressure taps in the midspan blade region, and strain gauges at the blade root. The retrofit applications consist of two Gurney flap heights of 0.5 % and 1.0 % in relation to the chord length, which are implemented perpendicular to the pressure side at the trailing edge. As a result, the Gurney flap configurations lead to performance improvements in terms of the axial wake velocities, the angles of attack and the lift coefficients. The enhancement of the root bending moments implies an increase in both the rotor torque and the thrust. Furthermore, the aerodynamic impact appears to be more pronounced in the tripped case compared to the clean case. Gurney flaps are considered a passive flow-control device worth investigating for the use on horizontal-axis wind turbines.

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Section: Introductionmentioning

confidence: 91%

Section: Gurney Flapsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

et al. 2020

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“…As such, for GF = 1.5 %c a vortex street is triggered while for GF = 0.5 %c the wake is shed in a relatively smooth way. In a similar manner, Alber et al (2017) suggest the use of very small GF-heights of approximately half the local BL thickness in order to maintain, or even improve the airfoil L/D-ratio of different DU and NACA airfoils.…”

Section: Introductionmentioning

confidence: 92%

Aerodynamic Effects of Gurney Flaps on the Rotor Blades of a Research Wind Turbine

Alber¹,

Soto‐Valle²,

Μανωλέσος³

et al. 2020

Preprint

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Abstract. This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 meters and the blade configurations consist of the clean and the tripped baseline cases emulating the effects of forced leading edge transition. The wind tunnel experiments include three operation points based on tip speed ratios of 3.0, 4.3 and 5.6, reaching Reynold numbers of approximately 250,000. The measurements are taken by means of three different methods; Ultrasonic Anemometry in the wake, surface pressure taps in the mid-span blade region and strain gauges at the blade root. The retrofit application consists of two Gurney flap heights of 0.5 % and 1.0 % in relation to the chord length, which are implemented perpendicular to the pressure side at the trailing edge. As a result, the Gurney flap configurations evoke performance improvements in terms of the axial wake velocities, the angles-of-attack and the lift coefficients. The enhancement of the root bending moments imply an increase of both the rotor torque and the thrust. Furthermore, the aerodynamic impact appears to be more pronounced in the tripped case compared to the clean case. Gurney flaps are considered a worthwhile passive flow-control device in order to alleviate the adverse effects of early separation and leading edge erosion of horizontal axis wind turbines.

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“…The study of Gurney flaps' implementation and performance has been widely reported, both experimentally and numerically. According to Alber et al [16], who analyzed wind tunnel tests for GFs on nine different airfoils and for different GF heights, GFs' effect on the C L / C D ratio is likely to be favorable as long as small heights are assumed. Moreover, they presented the effect on rotor blades computationally; the results suggest an enhanced power performance between 0.8% and 2.0% for small GF heights.…”

Section: Introductionmentioning

confidence: 99%

Computational Methods for Modelling and Optimization of Flow Control Devices

et al. 2020

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Over the last few years, the advances in size and weight for wind turbines have led to the development of flow control devices. The current work presents an innovative method to model flow control devices based on a cell-set model, such as Gurney flaps (GFs). This model reuses the cells which are around the required geometry and a wall boundary condition is assigned to the generated region. Numerical simulations based on RANS equations and with have been performed. Firstly, a performance study of the cell-set model on GFs was carried out by comparing it with a fully mesh model of a DU91W250 airfoil. A global relative error of 1.13% was calculated. Secondly, optimum GF lengths were determined (from 0% to 2% of c) for a DU97W300 airfoil and an application of them. The results showed that for lower angles of attack (AoAs) larger GFs were needed, and as the AoA increased, the optimum GF length value decreased. For the purpose of studying the effects generated by two flow control devices (vortex generators (VGs) and optimum GF) working together, a triangular VG based on the jBAY model was implemented. Resulting data indicated, as expected, that when both flow control devices were implemented, higher CL and lower CD values appeared.

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Parametric Investigation of Gurney Flaps for the Use on Wind Turbine Blades

Cited by 11 publications

References 0 publications

Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

Aerodynamic Effects of Gurney Flaps on the Rotor Blades of a Research Wind Turbine

Computational Methods for Modelling and Optimization of Flow Control Devices

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