A review and assessment of the rain erosion damage initiation of wind turbine blades leading edge protection systems based on laboratory testing data and industrial recommended practice DNVGL-RP-0573

Abstract

Protecting wind turbine blades, especially offshore, is challenging due to harsh atmospheric conditions. Leading edge protection (LEP) coatings prevent damage from high-speed droplet impacts. Rain erosion harms the blade surface, reducing aerodynamic performance and power production, leading to costly repairs. The wear damage caused by raindrop impacts can be viewed as a fatigue process, where damage accumulates until a specified damage limit is reached. Springer developed a model that is both analytical and empirical to relate rain impact resistance. This analytical model, cited extensively in rain erosion impact applications, has been used to evaluate erosion lifetime prediction and assess the relationship between atmospheric conditions and blade erosion risk. Springer model considers material performance under accelerated rain erosion test conditions and has been effectively applied to wind turbine blades. This research led to the industrial wind sector defining a recommended practice, DNVGL-RP-0573, 2020 to quantify and evaluate erosion lifetime formally. It suggests calculating accumulated erosion damage using rain erosion test results defined in lab conditions with the recommended practice DNVGL-RP-0171, 2018, to determine the model's material strength parameters. Quantifying the severity of erosion in wind turbine blades is challenging due to various factors, including meteorology, aerodynamics, materials science and wind turbine dynamics. All these studies require material characterization data that depends on lab testing conditions. This initial in-lab data performance can be extrapolated to in-field installation configurations for lifetime modeling evaluations. This work reviews the application of the Springer model to estimate rain erosion damage initiation in wind turbine blade leading edge protection systems and analyzes the industrial application of DNVGL-RP-0573 based on its modified application. Both methodologies are assessed using practical cases, allowing a complete comparison of modeling input data considering material fundamental properties and laboratory rain erosion testing fit data. Obtained modelled lifetime predictions agree well with in-field inspection data, and hence validate the models on the application with referenced coating materials.

Keywords: coatings, leading edge protection, modelling, rain erosion, wear fatigue