Anchor loads for shallow water mooring of a 15 MW floating wind turbine — Part I: Chain catenary moorings for single and shared anchor scenarios

Anchor loads for shallow water mooring of a 15 MW floating wind turbine—Part II: Synthetic and novel mooring systems

“…The present numerical study utilises OrcaFlex to model a 15 MW turbine supported by a semi-submersible floating foundation under conditions representative of the Celtic Sea off the UK's southwest coast. To allow direct comparison against the chain-catenary results presented by the authors in Part I (Pillai et al, 2022), the same numerical model and case study are considered, but with changes in the mooring system to include synthetic components in both catenary and taut configurations.…”

“…This article builds on previous work presented by Pillai et al (2022) and is laid out as follows: Section 2 presents the underlying coupled modelling framework utilised in the study and describes the case study, detailing the site considered, the environmental conditions simulated, the turbine, the floating platform, and the mooring components. Section 3 presents the results obtained which are discussed in greater detail in Section 4.…”

“…OrcaFlex's native coupled modelling is therefore used in the present work to simulate the floating wind turbine, implementing the floating structure and turbine as advised by the relevant definition documents (discussed further in Section 2.2). Verification of the base model was done against existing OpenFAST models for baseline catenary systems as described in Pillai et al (2022). Further verification of OrcaFlex's capabilities of accurately modelling dynamic behaviour of catenary and taut moorings can be found as part of OrcaFlex's Quality Assurance, Testing and Validation process (Quiggin, 2015).…”

“…It has also been found that one of these three load cases is generally the limiting ultimate limit state (ULS) case which governs the design of anchors and selection of mooring components (West et al, 2021). Pillai et al (2022) highlighted that cases in which winds and waves were misaligned could result in increased loads, the present work is limited to the consideration of cases where the wind and wave directions are collinear. Considering only the collinear cases allows the load mitigation potential and motion response characteristics of the mooring components to be studied and directly compared to the traditional chain-catenary systems without requiring a significant number of cases.…”

“…In order to effectively design and optimise sub-systems for these next generation scale devices, NREL and the IEA developed the IEA 15 MW reference turbine in 2020 (Gaertner et al, 2020). To evolve from the existing body of knowledge on the NREL 5 MW, Part I of this study (Pillai et al, 2022), presented results from coupled dynamic simulations of the IEA 15 MW reference turbine with a realistic reference semi-submersible platform (Allen et al, 2020). Environmental conditions representative of the relatively shallow Celtic Sea (a target site for this scale of technology (Estate, 2021)), were used to investigate the impact of mooring system design on platform dynamics and anchor loads.…”