New six degree of freedom model for ice throw simulations

Abstract

Icing and thus ice throw from wind turbines is currently unavoidable in cold climates. Therefore, the associated risk requires adequate quantification and assessment. In this study, a new six degree of freedom model with increased accuracy is introduced, which aims to overcome limitations of currently used approaches. This is achieved by taking into account translation and rotation of the thrown fragments and thus allowing to represent more complex trajectories. To limit the necessary numerical effort, look-up tables for forces and moments are pre-calculated with the help of CFD simulations. Validation of the model was achieved by comparison to real life experiments. For these, artificial ice fragments based on collected real fragments were produced and released from wind turbines under partially controlled conditions. This showed a significantly improved agreement between simulated and observed values when compared to the state-of-the-art model. Since the distribution patterns of the presented model differ significantly from those of the established model, these consequences must be taken into account in future risk assessments.