Thesis
Geometric shape parameterization and optimization of floating offshore wind turbine substructure within an MDAO framework
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T17086
- Person Identifier (Local)
- 202074056
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- The urgent need to reduce greenhouse gases to attain net zero emission and reverse climate change has put the world at a turning point to explore cleaner form of energy generation. This has spiked an increase in the offshore wind forms of energy generation and, most recently, a focus on the Floating Offshore Wind Turbine (FOWT) sector. However, despite the advantages of FOWT installations amongst which are; less environmental impact and accessibility to deeper waters for richer wind resources needed for significant power generation, the technology is presently still economically less viable in comparison to the fixed bottom foundation counterpart. Several research studies, aimed at ensuring the economic feasibility of FOWT have been performed, such as floating foundation upscaling, surrogate designs, and multidisciplinary design analysis and optimization (MDAO) approach. This research is exploring the use of parametric curves to alter the design shapes within an MDAO framework to improve design, reduce analysis’ computation time and ensure economic feasibility. This thesis conducted a detailed literature review on shape parameterization techniques and MDAO framework for floating offshore substructures, highlighting research gaps related to their design. The focus of this thesis is to develop a conceptual platform for the design, analysis, and optimization of floating substructures for offshore wind turbine systems using shape parameterization techniques within an MDAO framework. This thesis utilized shape parameterization techniques like the Non-Uniform Rational B-Spline approximation curve characterized with local propagation shape control properties within Sesam GeniE and hydrodynamic analysis tools using the potential flow methodology (HydroD and Wave Analysis by Diffraction and Morisson theory - WADAM). Other shape parameterization techniques like the Cubic Spline, Cubic Hermite Spline and B-Spline approximation curve along with the Non-Uniform Rational B-Spline were assessed. The B-spline parameterization technique is the best performance curve using the Technique for Order of reference by Similarity to Ideal Solution (TOPSIS) to assess the curves given a set of criteria amongst which are computational time, curve continuity and propagation properties and minimizing the objective function. These tools are interfaced on a developed platform with glue codes using Python object-oriented programming language. The automated process within the interface platform includes generating panel model design geometry based on a set of design variables provided, modelling the ballast compartment, meshing the models in preparation for hydrodynamic assessment, evaluating mass distribution and buoyancy with the derivation of the ballast mass distribution and conducting a hydrostatic assessment. The developed platform is further integrated with the gradient-free pattern search optimization algorithm with specified objective functions and constraints to select the most feasible design concept. The developed model, framework, and approaches in this thesis - especially the concept of shape parameterization within a multidisciplinary design analysis and optimization framework are of potentially high value for both research and the floating offshore wind industrial sector. The achievements of this thesis are summarized herein. 1. This thesis introduces a simplified and innovative design approach by integrating parametric curves into a Multidisciplinary Design Analysis and Optimization (MDAO) framework. This integrated method allows for the exploration of an extensive design space, facilitating the selection of an optimal design within a significantly reduced computational time frame. 2. The thesis evaluates the performance of a set of parametric curves—Cubic Spline, Cubic Hermite Spline, B-Spline, and Non-Uniform Rational B-Spline (NURBS)—within the MDAO framework. The evaluation, based on a set of performance criteria employing the multicriteria decision matrix approach of TOPSIS, identifies B-Spline as the top performer, followed by the Cubic Spline, NURBS, and Cubic Hermite Spline. 3. The thesis demonstrates that optimizing the shape of a Spar platform using the NREL 5MW turbine in a 30MW configuration has the potential to reduce the levelized cost of energy by up to 8% compared to conventional designs. This finding underscores the economic viability and efficiency gains achievable through shape optimization approach. This thesis provides valuable insights to diverse future applications, including enhanced design efficiency, reduced computational time for design and analysis, generation of unique design concepts for improved hydrodynamic performance, potential capital cost reduction, and lowered Levelized Cost of Energy (LCOE). Additionally, it paves the way for the advancement of advanced manufacturing techniques for unique shapes of floating foundations. These applications underscore the significance of the developed model framework, and approaches in advancing research, refining design practices, and fostering the development of economically viable and reliable support structures for floating offshore wind turbines.
- Advisor / supervisor
- Coraddu, Andrea
- Collu, Maurizio
- Resource Type
- DOI
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PDF of thesis T17086 | 2024-12-05 | Public | Download |