Early Concept Evaluation of Floating Vertical Axis Wind Turbines: Method development and testing utilizing FE-modelling, structural optimization and H-rotor designs
Examensarbete för masterexamen
Product development (MPPDE), MSc
This master thesis concerned constructing a method for evaluation of concepts of floating vertical axis wind turbines, FVAWT, with an H-rotor design at an early design phase. As optimization is used, further sub-concepts are also generated and evaluated. Furthermore, the method was utilized on two models for a 1 MW and 10 MW turbine. The project was conducted together with the company SeaTwirl. Their current turbine design was used to build the initial models. FE-modelling and optimization were performed in Ansys workbench. The focus was on structural modeling and optimization, with aerodynamic, gravitational, and centrifugal loads being the ones considered. The studied part of the FVAWT was the rotor, consisting of two struts per blade, three blades, and a tower. These parts were optimized with respect to cost by creating a goal function dependent on the mass and the vertical center of gravity. The considered structural constraints were the first eigenfrequency, fatigue of the tower, and the ultimate limit state, ULS, on blades and struts in form of maximum allowed strains. To facilitate the optimization, assumptions to simplify the model and reduce the number of parameters were introduced. The project resulted in a method considered feasible to obtain indications of an optimal design for a floating vertical axis wind turbine of H-rotor design. Possible designs for a 1 MW and a 10 MW rotor were also found by utilizing the developed method.