Numerical Model Development for a Deep-Water Floating Wind Turbine
A mooring-line dynamic amplification assessment for the Elevator concept near Curaçao
E.P.J. Cammeraat (TU Delft - Mechanical Engineering)
J.S. Hoving – Graduation committee member (TU Delft - Civil Engineering & Geosciences)
A. Metrikine – Graduation committee member (TU Delft - Civil Engineering & Geosciences)
André Steenhuis – Mentor (Allseas Engineering)
Vera Terlouw – Mentor (Allseas Engineering)
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Abstract
This thesis develops a numerical Rhino-OrcaWave-OrcaFlex model of the 15 MW Elevator floating wind concept near Curaçao and uses it to compare quasi-static (QS) and dynamic (DYN) mooring-line models. The site is characterised by deep water, with depths of about 800 m close to shore, making the mooring system an important part of the floating wind design problem.
The comparison focuses on selected first-order, wave-only irregular-wave cases. The QS and DYN simulations use the same floater representation, hydrodynamic database, mooring geometry, target pretension, unstretched line length, environmental input, wave seed, simulation settings, and post-processing method. The main response quantities are maximum horizontal platform offset and governing fairlead effective tension.
For the selected cases, the two mooring-line models give almost identical predictions. The largest horizontal offset is approximately 1.15 m, and the largest governing-line maximum effective tension is approximately 963.5 kN. The case-specific offset dynamic amplification factors range from 0.997 to 1.002, while the tension-range ratios remain below unity. The small differences are explained by the limited fairlead excitation in the selected first-order wave-only cases and by the separation between the dominant wave periods and the main moored-system response periods.
The results indicate that the QS mooring-line model is suitable for predicting maximum horizontal platform offset and governing fairlead effective tension within the selected comparison setup. This conclusion should not be generalised to wind-wave-current design cases, second-order wave-drift loading, current-induced line vibration, vortex-induced vibration, turbine-control effects, fatigue, or certification-level mooring design.