The impact of leading edge damage and repair on sectional aerodynamic performance

Blade leading edge damage is a major cost driver in the wind energy sector and are related to the environmental conditions under which the blades operate. The impact energy of the airborne particles striking the leading edge (LE) determines the speed of damage accumulation, thus blades are more severely affected towards their tips and with increasing tip speed. Due to their stochastic nature, the aerodynamic impact of LE damages is not easily quantified and hard to generalize. The same is true for other types of LE imperfections originating from the manufacturing process, repairs or LE protection solutions. In this study we idealize and parameterize 11 forms of LE surface imperfections - constituting damage and repair related realizations - and explore their impact on airfoil performance using 2D CFD and compare specific cases with wind tunnel measurements. Predictions and measurements agree favorably for a number of different LE damage types and an overview of the performance loss incurred by LE imperfections is presented. Surface steps, waviness and roughness are identified as main risks to airfoil performance. Sandpaper and rough wall boundary conditions seem viable proxies for representing the performance loss from LE perturbations in wind tunnel experiments and computations, respectively.