Preprints
https://doi.org/10.5194/wes-2021-124
https://doi.org/10.5194/wes-2021-124

  25 Nov 2021

25 Nov 2021

Review status: this preprint is currently under review for the journal WES.

Experimental investigation of Mini Gurney Flaps in combination with vortex generators for improved wind turbine blade performance

Jörg Alber1, Marinos Manolesos2, Guido Weinzierl-Dlugosch3, Johannes Fischer3, Alexander Schönmeier1, Christian Navid Nayeri1, Christian Oliver Paschereit1, Joachim Twele4, Jens Fortmann4, Pier Francesco Melani5, and Alessandro Bianchini5 Jörg Alber et al.
  • 1Technische Universität Berlin, Hermann-Föttinger Institut, Müller-Breslau-Str. 8, 10623 Berlin, Germany
  • 2College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, United Kingdom
  • 3SMART BLADE GmbH ®, Waldemarstr. 39, 10999 Berlin, Germany
  • 4Hochschule für Technik und Wirtschaft Berlin, Wilhelminenhofstraße 75A, 12459 Berlin, Germany
  • 5Università degli Studi di Firenze, Department of Industrial Engineering (DIEF), Via di Santa Marta 3, 50139 Firenze, Italy

Abstract. This wind tunnel study investigates the aerodynamic effects of Mini Gurney flaps (MGFs) and their combination with vortex generators (VGs) on the performance of airfoils and wind turbine rotor blades. VGs are installed on the suction side aiming at stall delay and increased maximum lift. MGFs are thin angle profiles that are attached at the trailing edge in order to increase lift at pre-stall operation. The implementation of both these passive flow control devices is accompanied by a certain drag penalty. The wind tunnel tests are conducted at the Hermann- Föttinger Institut of the Technische Universität Berlin. Lift is determined with a force balance and drag with a wake rake for static angles of attack from −5° to 17° at a constant Reynolds number of 1.5 million. The impact of different MGF heights including 0.25 %, 0.5 % and 1.0 % and an uniform VG height of 1.1 % of the chord length are tested on three airfoils that are characteristic for different sections of large rotor blades. Furthermore, the clean and the tripped baseline cases are considered. In the latter, leading edge transition is forced by means of Zig Zag (ZZ) turbulator tape. The preferred configurations are the smallest MGF on the NACA63(3)618 and the AH93W174 (mid to tip blade region) and the medium sized MGF combined with VGs on the DU97W300 (root to mid region). Next, the experimental lift and drag polar data is imported into the software QBlade in order to design a generic rotor blade. The blade performance is simulated with and without the add-ons based on two case studies. In the first case, the retrofit application on an existing blade mitigates the adverse effects of the ZZ tape. Stall is delayed and the aerodynamic efficiency is partly recovered leading to an improvement of the power curve. In the second case, the new design application allows for the design of a more slender blade while maintaining the power output. Moreover, the alternative blade appears to be more resistant against forced leading edge transition.

Jörg Alber et al.

Status: open (until 06 Jan 2022)

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Jörg Alber et al.

Jörg Alber et al.

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Short summary
This paper investigates the opportunities and limits of two additional devices that improve the aerodynamic performance of wind turbine rotor blades. The objective of attaching these relatively small add-ons is the optimization of the annual energy production over a time period of at least 20 years by mitigating the effects of typical wear-out effects, such as the surface erosion of rotor blades. Hence, the study is a contribution to the reliable and long-term generation of renewable energy.