OpenFAST Modeling of the T-Omega Wind Floating Offshore Wind Turbine System: Preprint

Lu Wang, Jason Jonkman, Jim Papadopoulos, Andrew Myers

Research output: Contribution to conferencePaper


To reduce the cost of offshore wind energy through a more efficient design of the floating support structure, T-Omega Wind developed a novel lightweight and shallow-draft platform concept that aims to achieve a wave-following behavior without resonance amplification. The rotor and generator are carried by four tower legs with each leg supported by a shallow-draft float at the base. In preparation for a more detailed analysis, a coupled aero-hydro-elastic model of the proposed concept is developed in OpenFAST. The detailed modeling approach is presented, including a novel application of the SubDyn substructure dynamics module of OpenFAST to approximate the loads on the axle tube at the tower top from the rotor hub bearings. Preliminary results obtained with the OpenFAST model by rigidifying the substructure and blades indicate that the original sizing of the design can lead to large hub acceleration in the axial/surge direction and in the pitch direction due to platform-pitch motion. The high hub acceleration also potentially leads to large bending moments in the four tower legs. To address the issue identified, an updated design is developed with, among other changes, increased float spacing at the tower base and improved geometry of the tower legs. The new design suggests significantly reduced extreme platform pitch angles under the same conditions and will be further analyzed in the future through full aero-hydro-servo-elastic simulations.
Original languageAmerican English
Number of pages14
StatePublished - 2024
EventASME 2023 5th International Offshore Wind Technical Conference - The Exeter University, Exeter, United Kingdom
Duration: 18 Dec 202319 Dec 2023


ConferenceASME 2023 5th International Offshore Wind Technical Conference
CityThe Exeter University, Exeter, United Kingdom

Bibliographical note

See NREL/CP-5000-89204 for paper as published in proceedings

NREL Publication Number

  • NREL/CP-5000-87168


  • FOWT
  • hydroelasticity
  • lightweight
  • OpenFAST
  • shallow draft


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