AN APPLICATION OF MDO TO LOW INDUCTION ROTORS USING HIGH FIDELITY STRUCTURAL MODELING TOOLS

Upscaling wind turbines has been an important technological trend in the past decade. For rotor design, this has led to the incorporation of structural and cost analyses to realize feasible designs, contrary to previous approaches in which the main design driver was aerodynamic performance. This evolution of the rotor design problem has made it a multi-disciplinary design optimization (MDO) problem, receiving attention from the scientific community in the form of new, MDO design frameworks and tools. As the upscaling trend develops, new design objectives have been proposed to this design problem. As a result, alternative approaches to the Betz optimal-oriented design have been introduced, such as the Low Induction Rotor (LIR). The LIR, which includes blade radius within its optimization, introduces a structural constraint in the form of root blade bending moment M0. This intrinsically multidisciplinary problem has not been sufficiently tested in MDO environments, usuallyl acking mid to high fidelity analysis in the structural discipline. This master thesis reviews the LIR design theory and demonstrates its application within the context of MDO, also presenting an alternative constraint in the form of maximum tip deflection δt. The optimization problem is formulated by leveraging the use of a parameterized axial induction distribution along the blade span, which provides a set of free variables. The set of free variables is changed in a range to materialize variations of traditional LIR theory, allowing a design space exploration to obtain pareto optimal families of blades, alternate to the IEA 15 MW reference turbine.