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Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
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The length of rotor blades of land-based wind turbines is currently constrained by logistics constraints. Turbine manufacturers currently propose segmented solutions to overcome these limits, but blade joints come with extra masses and costs. This work investigates an alternative solution, namely the design of ultra-flexible blades that can be transported on rail via controlled bending. The results show that this is a promising pathway to further increase the size of land-based wind turbines.
Preprints
https://doi.org/10.5194/wes-2021-29
https://doi.org/10.5194/wes-2021-29

  01 Jun 2021

01 Jun 2021

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

Land-based wind turbines with flexible rail transportable blades – Part I: Conceptual design and aeroservoelastic performance

Pietro Bortolotti1, Nick Johnson1, Nikhar J. Abbas1,2, Evan Anderson3, Ernesto Camarena3, and Joshua A. Paquette3 Pietro Bortolotti et al.
  • 1National Renewable Energy Laboratory, Boulder, CO 80303, USA
  • 2University of Colorado Boulder, Boulder, CO 80309, USA
  • 3Sandia National Laboratories, Albuquerque, NM 87185, USA

Abstract. This work investigates the conceptual design and the aeroservoelastic performance of land-based wind turbines whose blades can be transported on rail via controlled bending. The turbines have a nameplate power of 5 MW and a rotor diameter of 206 m, and they aim to represent the next generation of land-based machines. Three upwind designs and two downwind designs are presented, combining different design goals together with conventional glass and pultruded carbon fiber laminates in the spar caps. The results show that controlled flexing requires a reduction in the flapwise stiffness of the blades, but it represents a promising pathway to increase the size of land-based wind turbine rotors. Given the required stiffness, the rotor can be designed either downwind with standard rotor preconing and nacelle uptilt angles or upwind with higher-than-usual angles. A downwind-specific controller is also presented, featuring a cut-out wind speed reduced to 19 m per second and a pitch-to-stall shutdown strategy to minimize blade-tip deflections toward the tower. The flexible upwind and downwind rotor designs equipped with pultruded carbon fiber spar caps are found to generate the lowest levelized cost of energy, 2.9 % and 1.3 %, respectively, less than the segmented design. The paper concludes with several recommendations for future work in the area of large flexible wind turbine rotors.

Pietro Bortolotti et al.

Status: open (until 13 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wes-2021-29', Athanasios Barlas, 04 Jun 2021 reply

Pietro Bortolotti et al.

Pietro Bortolotti et al.

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Short summary
The length of rotor blades of land-based wind turbines is currently constrained by logistics constraints. Turbine manufacturers currently propose segmented solutions to overcome these limits, but blade joints come with extra masses and costs. This work investigates an alternative solution, namely the design of ultra-flexible blades that can be transported on rail via controlled bending. The results show that this is a promising pathway to further increase the size of land-based wind turbines.
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