An experimental approach to analysing rain droplet impingement on wind turbine blade materials

Leading edge erosion of wind turbine blades is an important issue within the industry and has been found to have a substantial impact on the annual energy output of generators. This forces operators to make blade repair a necessity, adding to the operation and maintenance costs of a project. A wind turbine’s tip speed can in some cases have an upper limit based on the erosion exhibited on the leading edge. This paper explores the variables of rainfall rate and impact velocity of the impinging droplets in an attempt to explore the recovery time of the tri-axial composite material used. It is shown that an increase in impact velocity results in a higher mass loss than an increase in the rainflow rate. Analysis using a scanning electron microscope reveals that pin holes in the laminate surface are exploited by the droplets, acting as initiation point for erosion of the composite. Overall the results suggest that the tip speed of the wind turbine blade is of greater importance when compared to the relevant rainfall conditions as to where the wind turbine is situated