ISBN 9783843954556

978-3-8439-5455-6, Reihe Ingenieurwissenschaften

Giorgia Guma
High-Fidelity Aeroelastic Analyses of Wind Turbines in Complex Terrain

155 Seiten, Dissertation Universität Stuttgart (2024), Hardcover, A5

Zusammenfassung / Abstract

This thesis presents high-fidelity Fluid-Structure-Interaction (FSI) investigations performed on the research wind turbine of the WINSENT project. The FSI is calculating combining the Computational Fluid Dynamics (CFD) code FLOWer with the multiphysics Finite Element Method (FEM) solver KRATOS, which can model the turbine using both beam and shell structural elements. The two codes are coupled in both an explicit and implicit way. The different modelling approaches strongly differ with respect to computational resources and therefore the advantages of a higher accuracy must be weighted with the respective additional computational costs. The described FSI coupling approach is initially used with a simplified wind turbine model consisting of a single blade under uniform inflow conditions. The same model has been then simulated in non-rotating conditions with extremely high inflow velocities able to trigger Vortex Induced Vibrations (VIV). The responses of the different structural elements and coupling algorithms have been shown, together with a deep flow analysis with both a rigid and a flexible blade, in combination with a Dynamic Mode Decomposition (DMD) of the flow field. Afterwards, the aerodynamic complexity is increased considering the full turbine with turbulent inflow conditions generated from real field data, in both flat and complex terrains. It is shown that in these cases a higher structural fidelity is necessary. The effects of aeroelasticity are then shown on the phase-averaged blade loads, showing that using the same inflow turbulence, the flow field in the flat terrain is mostly influenced by the shear, while the one in complex terrain is mostly affected by low-velocity structures generated by the forest. Afterwards, the impact of aeroelasticity and turbulence on the Damage Equivalent Loading (DEL) is discussed, showing that flexibility is reducing the DEL in case of turbulent inflow, acting as a damper breaking larger cycles into smaller ones.