Multiple limit cycle amplitudes in high-fidelity predictions of standstill wind turbine blade vibrations

Abstract. In this study, vortex-induced vibrations (VIVs) on the IEA 10 MW blade are investigated using two methodologies in order to assess strengths and weaknesses of simulation types. Both fully coupled fluid–structure interaction (FSI) simulations computational fluid dynamics (CFD) with forced motion used compared. It is found that for studied cases high inclination angles, forced-motion succeed capturing power injection by aerodynamics, despite being simplified. From simulations, a dependency initial conditions was found, showing which stable if unperturbed might go into large VIVs provoked initially by, instance, inflow turbulence or turbine operations. Depending vibration amplitudes, multiple limit cycle levels can be triggered, same flow case, due non-linearity aerodynamics. By fitting simple damping model specific mode shape from FSI it also demonstrated equilibrium amplitudes between dissipation estimated even cases, good agreement simulations. Finally, time series generation presented, concluding CFD amplitude sweeps estimate not only final oscillation amplitude, but build-up series.