OC6 Phase I: Improvements to the OpenFAST Predictions of Nonlinear, Low-Frequency Responses of a Floating Offshore Wind Turbine Platform

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27 Scopus Citations

Abstract

In the OC5 and OC62 projects, the authors observed a persistent underprediction of the nonlinear, low-frequency responses of an offshore wind semisubmersible with many mid-fidelity engineering models, including the OpenFAST tool developed by the National Renewable Energy Laboratory. Both the low-frequency wave excitation in surge and pitch and the resulting resonance motions were severely underpredicted. In response, we developed several modifications to the OpenFAST model from the OC5/6 projects to improve the predictions of the low-frequency wave loads and responses. All modifications are in the modeling of the viscous drag forces. Efforts were made to provide physical justifications to the changes and to limit the number of additional parameters requiring tuning, so that the modified model can be applied to other floating wind systems. With the proposed modifications, the predictions of the low-frequency surge and pitch wave loads on a fixed floater and the resonance responses of a floating structure are both significantly improved with a single set of model coefficients, which leads to good agreement with the measurements from the OC6 wave-basin experimental campaign.

Original languageAmerican English
Pages (from-to)282-301
Number of pages20
JournalRenewable Energy
Volume187
DOIs
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 Elsevier Ltd

NREL Publication Number

  • NREL/JA-5000-81554

Keywords

  • Low frequency
  • OC6
  • Offshore wind
  • OpenFAST
  • Resonance
  • Semisubmersible

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