Wind Turbine Blade Surface Roughening and Plastic Emission Due to Leading Edge Erosion: Multiple Impact Modeling Framework

This paper presents a multiple water droplet impact finite element model that can be used to simulate high strain rate water droplet erosion processes for various target materials. The model is able to provide predictions for mass loss and the evolution of erosion depth as a function of the number of impacts. This is achieved through a continuum damage mechanics approach coupled with element deletion for the target material. Validation of the model is performed by comparison with water droplet erosion data for PMMA. We apply the model to estimate the emissions of microplastics from wind turbines due to blade erosion. For adverse weather and operational conditions, our worst-case estimate was to the order of 340 g per blade per year. The developed framework is also used to model the effect of flaws in the blade coating on erosion progression. The effect of internal defects (voids) in the coatings on the erosion depth evolution was studied numerically. The presence of internal voids led to earlier coating breakthrough and exposure of the substrate material. The model can be used to study the effects of various types of flaws during both the incubation and mass loss stages of erosion.