Experimental investigation of floating offshore wind turbine dynamics under misaligned wind and wave conditions

Journal article

Floating offshore wind turbines (FOWTs) provide a promising pathway toward global Net-Zero targets by harnessing deep-water wind resources for sustainable energy generation. Wind- and wave-induced platform motions influence energy yield and structural performance, so accurate prediction of FOWT dynamics under representative environmental conditions is essential prior to large-scale deployment. Although most studies assume aligned wind and wave directions, these conditions are frequently misaligned in reality. Almost all previous studies of wind-wave misalignment have been numerical due to the difficulty of designing an experiment with misaligned wind and waves. In this study, we present an experimental investigation of misaligned wind and waves on the VolturnUS-S semi-submersible platform with the IEA 15 MW turbine. Three environmental conditions are simulated, representative of key design load cases for a location in the Celtic Sea (United Kingdom), for four different wind directions. Platform motion, mooring line tension and fore-aft nacelle acceleration are analysed to evaluate misalignment effects on spectral characteristics and extreme values. We find that turbulent wind loading shifts the platform’s peak response frequency and induces an additional low-frequency peak in surge motion. Pitch motion is shown to be damped for a 60^◦ misalignment between wind and waves, which corresponds to aerodynamic thrust alignment with the platform line of symmetry. Nacelle fore-aft acceleration is shown to be maximum for a 90^◦ misalignment angle, demonstrating a potential key case in fatigue and ultimate limit-state analysis. This experimental analysis provides critical insight into misaligned wind-wave loading and supports the development of more robust design methodologies for FOWTs operating under realistic environmental conditions.

Authors: Shi, L; Adcock, TAA; Hann, M; Greaves, D; Edwards, EC

• Publication status: Accepted
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: Journal of Ocean Engineering and Marine Energy
• Acceptance date: 2026-08-30
• EISSN: 2198-6452
• ISSN: 2198-6444
• Language: English
• Keywords: floating offshore wind; wind-wave misalignment; real-time hybrid test; physical modelling; standards for wind-wave misalignment