Simulation of Damage for Wind Turbine Blades Due to Airborne Particles

A mathematical model and simulation of airborne particle collisions with a 38 m, 1.5 MW horizontal axis wind turbine blade are presented. Two types of particles were analyzed, namely insects and sand grains. Computations were performed using a two-dimensional inviscid flowfield solver coupled with a particle position code. Three locations along the blade were considered and characterized by airfoils of the DU series. The insect simulations estimated the residual debris thickness on the blade, while sand simulations computed the surface erosion rate. Results show that the impact locations along the blade depend on angle of attack, freestream velocity, airfoil shape, and particle mass. Particles were found to collide primarily at the leading edge. The volume of insect debris per unit span was maximum at r/ R = 0.75. The erosion rate due to sand was maximum on the low pressure side of the blade. An erosion rate approximately ten times higher was observed at r/ R = 0.75, as compared with the section at r/ R = 0.35. Near the leading edge, large angles of impact occurred and erosion rate had a minimum, while it reached maximum values slightly downstream where the impact angle was more skewed.