Study on mixed-phase icing of rotating wind turbine blades

Mixed-phase icing, characterized by the coexistence of supercooled water droplet and ice crystal, is a critical issue to the operation of wind turbines. This study is based on the Euler–Euler multiphase flow framework, combined with an extended Messinger thermodynamic model and an ice sticking–erosion model, to establish a three-dimensional rotating mixed-phase icing model of full-scale wind turbine blades. The results reveal that the mixed-phase icing model achieves an accuracy of 73.4% compared to experimental data, while the single supercooled droplet icing model reaches 91.7% accuracy. At the total water content of 1.0 g/m3, with the liquid water content to the ice water content ratio of 0.5/0.5 or lower, streamlined ice shapes are observed at the 0.95R blade section, where ice crystal sticking predominantly controls icing. In contrast, when the ratio exceeds 0.5/0.5, the ice develops an angular morphology, which suggests that water film dynamics primarily control the icing process. Additionally, droplet median volume diameter (MVD) significantly influences mixed-phase icing behavior, with sticking effects showing a positive correlation with droplet MVD. These findings provide valuable insights for predicting icing characteristics on three-dimensional rotating wind turbine blades.