Robert Bitsche

Aero-Elastic Optimization of a 10 MW Wind Turbine

This article presents the multi-disciplinary wind turbine analysis and optimization tool HawtOpt2 that is based on the open-source framework OpenMDAO, and interfaces to several state-of-the art simulation codes, which allows for a wide variety of problem formulations and combinations of models. In this article simultaneous aerodynamic and structural optimization of a 10 MW wind turbine rotor is carried out with respect to material distribution and outer shape. A set of optimal designs with respect to mass and AEP are presented, which shows that an AEP biased design can increase AEP with 1.5% while a mass biased design can achieve mass savings of up to 20% compared to the baseline DTU 10MW RWT. A newly developed frequency-domain based fatigue model is used to minimise fatigue damage, which achieves up to 8% reduction in the tower bottom fore-aft fatigue damage, with only limited reductions of the aerodynamic performance or increased mass.

Quick Method for Aeroelastic and Finite Element Modeling of Wind Turbine Blades

In this paper a quick method for modeling composite wind turbine blades is developed for aeroelastic simulations and finite element analyses. The method reduces the time to model a wind turbine blade by automating the creation of a shell finite element model and running it through a cross-sectional analysis tool in order to obtain cross-sectional properties for the aeroelastic simulations. The method utilizes detailed user inputs of the structural layup and aerodynamic profile including ply thickness, orientation, material properties and airfoils to create the models. After the process is complete the user has two models of the same blade, one for performing a structural finite element model analysis and one for aeroelastic simulations. Here, the method is implemented and applied to reverse engineer a structural layup for the NREL 5MW reference blade. The model is verified by comparing natural frequencies to the reference blade. Further, the application to aeroelastic and structural evaluations is demonstrated. Aeroelastic analyses are performed, and predicted fatigue loads are presented. Extreme loads from the aeroelastic simulations are extracted and applied onto the blade for a structural evaluation of the blade strength. Results show that the structural properties and natural frequencies of the developed 5MW blade match well with the reference blade, however the structural analysis found excessive strain at 16% span in the spare caps that would cause the blade to fail.Copyright