Leading Edge Erosion (LEE, material loss) on wind turbine blades reduces electrical power production by up to 5% and causes substantial repair costs. LEE is linked to material stresses induced by impacts from falling hydrometeors. Computational fluid dynamics simulations are conducted to quantify collision efficiency with rotating wind turbine blades as a function of hydrometeor size.
Excess LEE may be costing the wind energy industry tens of millions of dollars per year via lost revenue and/or increased maintenance costs and poses a threat to achieving continuing wind energy cost reductions. This study quantifies how hydrometeor impact probabilities with rotating blades vary as a function of hydrometeor diameter and wind speed.
Wind energy has exhibited dramatic cost reductions and there are projections for continued reductions in the Levelized Cost of Energy from wind turbines. The tendency towards deployment of larger wind turbines with increased rotor tip speeds may be associated with increased risks of precipitation-induced damage to the wind turbine blade leading edge and the resulting degradation of electricity generation and increased repair costs. The extent of erosion appears to be controlled, at least in part by local meteorological conditions; specifically, by the accumulated kinetic energy transfer from collisions with falling hydrometeors (precipitation). However, the aerodynamics of flow around wind turbine blades means not all falling hydrometeors will impact the blade, and at least in principle, some will be sufficiently small to follow the streamlines and thus avoid collisions with the rotating blades. Here, we present the set-up for computational fluid dynamics (CFD) simulations designed to quantify collision efficiency as a function of hydrometeor size for a simplified three-blade turbine using ANSYS Fluent 19.2 as the main numerical solver. The simulations correctly reproduce the pressure variability across the blade and illustrate that the variations in the droplet-blade collision probability are a function of wind speed, rain intensity, and droplet diameter.