Modelling Leading Edge Erosion of Wind Turbine Blades

Abstract

Wind turbines have substantially contributed to sustainable energy transitions over the last two decades, harvesting renewable energy. The installed wind turbine rotor blades are exposed to all weather conditions throughout their lifetime, wearing down the surfaces, especially the leading edges. The increased surface roughness amplifies the drag forces and, hence, decreases the aerodynamic performance. Forecasting models are needed to evaluate the economic benefit of repair realistically for certain erosion states of wind turbine blades. Although numerous methodologies exist for loss prediction due to surface roughness, the development and validation of such models are needed. Therefore, we establish numerical flow simulation methodologies to predict torque losses for eroded (below mesh resolution) and severely damaged (of the order of the mesh resolution) wind turbine wings. While severe damages, such as delamination, can be described by the computational mesh, the required roughness representation at the subgrid-scale is performed using the amplification roughness model. Being an extension of the Langtry-Menter γ-Reθt turbulence model, the amplification roughness model can handle the transition prediction between laminar and turbulent flow regimes even for rough surfaces. The reliability of the suggested methodologies is validated by two-dimensional test cases from literature for representative airfoils and erosion states.