Thesis

Multidisciplinary design analysis and optimisation for conceptual design of floating offshore wind turbine support structures

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Awarding institution
  • University of Strathclyde
Date of award
  • 2026
Thesis identifier
  • T18031
Person Identifier (Local)
  • 202079458
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • Floating offshore wind turbines (FOWTs) enable wind energy harvesting in deeper waters, where wind resources are stronger and more consistent, supporting climate targets. However, their design is challenged by complex subsystem interactions, harsh metocean conditions, and competing performance requirements over long lifetimes. Current concept design typically relies on simplified models and sequential subsystem development, thereby limiting design scope and increasing the risk of overlooking globally optimal solutions. Despite recent advances, there remains a lack of a holistic, verified approach for integrated conceptual design optimisation. This thesis aims to improve the efficiency and scope of support-structure conceptual optimisation by applying multidisciplinary design analysis and optimisation (MDAO) and a multi-domain, surrogate-supported numerical modelling framework. To support this aim, the optimisation problem is formulated in line with offshore standards, integrating serviceability, ultimate, and fatigue constraints, while remaining applicable to early-stage design. A novel resonance-avoidance constraint is introduced that is based on the probability and power content of excitation frequencies. A modular MDAO framework is developed to efficiently evaluate objectives and constraints. A hybrid frequency–time domain dynamic model is proposed, combining frequency-domain efficiency for motion prediction with time-domain accuracy for load and fatigue assessment. Key computational bottlenecks are mitigated by machine-learning models for hydrodynamic coefficients and mooring loads, applicable beyond a single project. Complementing the system-level optimisation, the thesis investigates fundamental FOWT motion characteristics via the instantaneous centre of rotation (ICR). A methodology is developed to identify the ICR from numerical simulations. The results challenge a common assumption of a fixed centre of rotation and provide design insights. The proposed methods are demonstrated through optimisation case studies, which illustrate efficiency gains, broader exploration of the design space, and new system-level insights. Collectively, this work establishes a foundation for efficient, integrated, and robust FOWT conceptual design, enhancing confidence in optimisation-based methods for next-generation FOWTs.
Advisor / supervisor
  • Collu, Maurizio
  • Coraddu, Andrea
Resource Type
DOI

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