Land-Based Wind Turbines with Flexible Rail Transportable Blades - Part I: Conceptual Design and Aeroservoelastic Performance

Pietro Bortolotti, Nick Johnson, Nikhar Abbas, Evan Anderson, Ernesto Camarena, Joshua Paquette

Research output: Contribution to journalArticle


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.
Original languageAmerican English
Number of pages22
JournalWind Energy Science Discussions
StatePublished - 2021

Bibliographical note

See NREL/JA-5000-81254 for final paper as published in Wind Energy Science

NREL Publication Number

  • NREL/JA-5000-78156


  • controlled flexing
  • land-based wind
  • logistics
  • mdao
  • openmdao
  • rail transport
  • WEIS
  • wind turbine design
  • wisdem


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