Causes & Impact
LEE is caused by repeated bombardment, primarily by raindrops and particulate matter, hail, ice, salt and UV, which create erosion and cause surface roughness. Ever larger rotor blades have resulted in increasing rotation speeds of the blade tips. The tips of offshore wind turbine blades can exceed 330 km/h. At these speeds, raindrops and hailstones create multiple shock wave impacts on the blade surface, which damage the blade surface or any Leading Edge Protection (LEP), including the adhesive bond that secures the LEP to the blade surface. Ultimately, rain and particulate bombardment can erode the surface coating and LEP layers, and eventually expose the blade laminate. The tip sections and leading edges (LE) of the blades are worst affected. The surface roughness that results from this erosion process creates resistance and drag, which impairs the aerodynamic performance of a blade; the air flow, lift and drag, reducing WTG efficiency and therefore decreasing the generating capacity of a windfarm, which consequently reduces Annual Energy Production (AEP) and therefore Return on Investment (ROI).