The transitional states of a floating wind turbine during high levels of surge

Ryan Kyle, Wolf-Gerrit Fruh

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)
72 Downloads (Pure)


With the deployment of floating offshore wind turbines, the effect of their wind- and wave-induced platform motion on the turbine’s performance and life is of concern and requires low-order models to develop appropriate control strategies. This work focusses on platform surge as one of the main additional degrees of freedom. The aerodynamic behaviour during the rotor’s transition into propeller state is explored by assessing the spanwise and rotor-integrated aerodynamic forces on the rotor of the NREL 5 MW turbine through a 3D URANS CFD simulation. The CFD findings are compared with a modified actuator disk (AD) theory and 2D Blade-Element Momentum (BEM) approach. It was In addition to propeller state, where both rotor torque and thrust are negative, two other states were observed with opposite signs of torque and thrust: a braking state, with negative torque but positive thrust, and the second a quasi-windmill state with thrust negative yet torque positive. The results demonstrate that BEM coupled with AD can reliably predict the transitions to these states during such high levels of platform surge and give hints to how the underpinning force balances are affected by temporal perturbations.
Original languageEnglish
Pages (from-to)1469-1489
Number of pages21
JournalRenewable Energy
Early online date14 Oct 2022
Publication statusPublished - Nov 2022


  • Floating offshore wind turbine
  • surge motion
  • braking state
  • propeller state
  • quasi-windmill state
  • OpenFOAM

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Mechanical Engineering


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