High fidelity aeroelastic stability analysis of operating wind turbines

In the light of steadily growing wind turbines with more flexible and complex blades, accuracy in aerodynamic modeling is of great importance. Therefore, this study explores the possibilities and implications of using high-fidelity computational fluid dynamics (CFD) simulations in aeroelastic stability analysis. This work details an efficient setup including forcing sequences and subspace identification to compare the modal parameters obtained with blade element momentum (BEM)- and CFD-based modeling. The data-driven approach works with simulated time series of any fidelity or complexity, and even physical experiments or field measurements. The resulting time series reveal slight differences in operating conditions, which carry on to the identified modal parameters. There is a good agreement across codes for the frequency, with maximum differences below 0.5%. Larger differences are reported on the damping ratios, where FSI returns damping values up to 30%, or 2%-points, lower than BEM at high wind speeds. This difference can also be found in the flapwise component of the high-resolution mode shapes, which otherwise align well.