Wind Turbine Blade Leading Edge Erosion: An Investigation of Rain Droplet and Hailstone Impact Induced Damage Mechanisms

Leading edge erosion of modern wind turbine blades is a growing and developing issue within the wind industry, effecting blade performance and efficiency. Little is known, researched or published on the phenomenon and there are currently no apparent full-proof material solutions for the issue. The research presented here looks to develop a fuller understanding of the issue of leading edge erosion, through first reviewing the literature (both within and outwith wind energy) on the topic to put the issues in context, and then subsequently further exploring and investigating the key damage mechanisms associated rain droplet and hailstone impact on the blade leading edge; identified as two of the most erosive types of environmental exposure. Both numerical (finite element) and experimental methods are employed to identify the key damage mechanisms associated with each form of impact in the different possible blade material coating and substrate systems. It is found that for rain exposure, surface degradation and erosion is a real risk for classical gelcoat coating systems. Whereas, for newer flexible and more erosive resistant materials, interface damage and debonding from the substrate is the most likely form of damage creation. Hailstone impact is found to pose a heightened erosive threat in comparison to rain, based on individual impact damage creation; although it is recognised that hailstorms are far more infrequent than rain showers in most regions. However, it is predicted that for extreme hailstones of sufficient mass, significant substrate composite damage could also be created through impact on the leading edge. Future work and further research development aimed at further understanding the issues of blade leading edge erosion are also identified and discussed.