Liquid droplet impact pressure on (elastic) solids for prediction of rain erosion loads on wind turbine blades

Leading edge erosion of wind turbine blades is causing high maintenance cost and therefore higher levelized cost of energy (LCOE). In order to lower the LCOE and to design reliable blades, the causes of rain erosion have to be understood. Traditionally, the (modified) waterhammer pressure equation is used to determine the contact pressure between the liquid droplet and the (elastic) target. This equation however is independent of time, droplet size and distance to the center of impact which have been identified as important parameters. This paper focuses on the fundamental impact mechanisms and proposes a numerical model that conforms to these mechanisms to determine the dynamic contact pressure between the liquid droplet and the elastic target. The effect of variations in droplet diameter, impact velocity and target elasticity on the resulting contact pressure profiles was investigated. The output of the model can be used for low cost 2D axisymmetric finite element simulations to determine the mechanical performance of coating systems for wind turbine blades and allows for material and geometry optimization.