Preprints
https://doi.org/10.5194/wes-2022-61
https://doi.org/10.5194/wes-2022-61
 
15 Jul 2022
15 Jul 2022
Status: this preprint is currently under review for the journal WES.

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

Christian Grinderslev, Niels Nørmark Sørensen, Georg Raimund Pirrung, and Sergio González Horcas Christian Grinderslev et al.
  • Department of Wind Energy, Technical University of Denmark, Risø Campus, 4000, Roskilde

Abstract. In this study, vortex induced vibrations (VIVs) on the IEA10MW blade are investigated using two methodologies in order to assess strengths and weaknesses of the two simulation types. Both fully coupled fluid-structure interaction (FSI) simulations and computational fluid dynamics (CFD) with forced motion of the blade are used and compared. It is found that for the studied cases with high inclination angles, the forced motion simulations succeed in capturing the power injection by the aerodynamics, despite the motion being simplified. From the fully coupled simulations, a dependency of initial conditions of the vibrations was found, showing that cases which are stable if unperturbed, might go into large VIVs if provoked initially by for instance inflow turbulence or turbine operations. Depending on the initial vibration amplitudes, multiple limit cycle levels can be triggered, for the same flow case, due to the non-linearity of the aerodynamics. By fitting a simple damping model for the specific blade and mode shape from FSI simulations, it is also demonstrated that the equilibrium limit cycle amplitudes between power injection and dissipation can be estimated using forced motion simulations, even for the multiple stable vibration cases, with good agreement to fully coupled simulations. Finally, a time series generation from forced motion simulations and the simple damping model is presented, concluding that CFD amplitude sweeps can estimate not only the final limit cycle oscillation amplitude, but also the vibration build-up time series.

Christian Grinderslev et al.

Status: open (until 26 Aug 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Christian Grinderslev et al.

Christian Grinderslev et al.

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Short summary
As wind turbines increase in size, the risk of flow induced instabilities increase. This study investigates the phenomenon of vortex induced vibrations (VIVs) on a large 10MW wind turbine blade using two high fidelity methods. It is found that VIVs can occur with multiple equilibrium states for the same flow case, showing an dependence on the initial conditions. This means that a blade, which is stable in a flow, can become unstable if e.g. a turbine operation provokes an initial vibration.