Date of Award

Summer 8-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Advisor

Andrew Goupee

Second Committee Member

Richard Kimball

Third Committee Member

Anthony Viselli

Abstract

Floating offshore wind turbines are a promising technology to address energy needs utilizing wind resources offshore. The current state of the art is based on heavy, expensive platforms to survive the ocean environment. Typical design techniques do not involve optimization because of the computationally expensive time-domain solvers used to model motions and loads in the ocean environment. However, this project uses an efficient frequency domain solver with a genetic algorithm to rapidly optimize the design of a novel floating wind turbine concept. The concept utilizes liquid ballast mass to mitigate motions on a lightweight post-tensioned concrete platform, with a target of half the levelised cost of energy of current technologies.

This thesis will present the optimization methodology for the cruciform hull design with tuned mass dampers and IEA 15 MW turbine. The need for lowering the levelised cost of energy of offshore wind technologies is explained, along with the challenges of reducing cost in these floating systems. A method utilizing a staged constraint handling technique coupled with a genetic algorithm is developed, encompassing input variable selection, hydrostatic constraints, and dynamic constraints. Finally, results of the optimization are presented, including wind and wave conditions, hull and turbine specifications, and convergence criteria. Finally, a conclusion on the results of the optimization is made and suggestions for future work are presented.

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