Towards multidisciplinary design optimization capability of horizontal axis wind turbines

dc.contributor.authorMcWilliam, Michael Kenneth
dc.contributor.supervisorCrawford, Curran of Mechanical Engineeringen_US of Philosophy Ph.D.en_US
dc.description.abstractResearch into advanced wind turbine design has shown that load alleviation strategies like bend-twist coupled blades and coned rotors could reduce costs. However these strategies are based on nonlinear aero-structural dynamics providing additional benefits to components beyond the blades. These innovations will require Multi-disciplinary Design Optimization (MDO) to realize the full benefits. This research expands the MDO capabilities of Horizontal Axis Wind Turbines. The early research explored the numerical stability properties of Blade Element Momentum (BEM) models. Then developed a provincial scale wind farm siting models to help engineers determine the optimal design parameters. The main focus of this research was to incorporate advanced analysis tools into an aero-elastic optimization framework. To adequately explore advanced designs with optimization, a new set of medium fidelity analysis tools is required. These tools need to resolve more of the physics than conventional tools like (BEM) models and linear beams, while being faster than high fidelity techniques like grid based computational fluid dynamics and shell and brick based finite element models. Nonlinear beam models based on Geometrically Exact Beam Theory (GEBT) and Variational Asymptotic Beam Section Analysis (VABS) can resolve the effects of flexible structures with anisotropic material properties. Lagrangian Vortex Dynamics (LVD) can resolve the aerodynamic effects of novel blade curvature. Initially this research focused on the structural optimization capabilities. First, it developed adjoint-based gradients for the coupled GEBT and VABS analysis. Second, it developed a composite lay-up parameterization scheme based on manufacturing processes. The most significant challenge was obtaining aero-elastic optimization solutions in the presence of erroneous gradients. The errors are due to poor convergence properties of conventional LVD. This thesis presents a new LVD formulation based on the Finite Element Method (FEM) that defines an objective convergence metric and analytic gradients. By adopting the same formulation used in structural models, this aerodynamic model can be solved simultaneously in aero-structural simulations. The FEM-based LVD model is affected by singularities, but there are strategies to overcome these problems. This research successfully demonstrates the FEM-based LVD model in aero-elastic design optimization.en_US
dc.identifier.bibliographicCitationMichael McWilliam and Curran Crawford. The Behavior of Fixed Point Iteration and Newton-Raphson Methods in Solving the Blade Element Momentum Equations. Wind Engineering, 35(1):17–31, December 2010en_US
dc.identifier.bibliographicCitationM. K. McWilliam, G. C. van Kooten, and C. Crawford. A method for optimizing the location of wind farms. Renewable Energy, 48:287–299, June 2013en_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectHorizontal Axis Wind Turbineen_US
dc.subjectMultidisciplinary Design Optimizationen_US
dc.subjectGeometrically Exact Beam Theoryen_US
dc.subjectBlade Element Momentum Theoryen_US
dc.subjectWind Farm Sitingen_US
dc.subjectVariationaly Asymptotic Beam Sectionen_US
dc.subjectLagrangian Vortex Dynamicsen_US
dc.subjectNumerical Stabilityen_US
dc.subjectLifting Line Theoryen_US
dc.subjectComposite Materialsen_US
dc.subjectLinear Beam Theoryen_US
dc.subjectFinite Element Methoden_US
dc.titleTowards multidisciplinary design optimization capability of horizontal axis wind turbinesen_US


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