Design of leading edge erosion-resistant airfoils using CFD-based shape optimization

Leading edge erosion significantly degrades wind turbine aerodynamic performance and economic value. We propose a new CFD-based shape optimization methodology for designing erosion-resistant airfoils. Unlike state-of-the-art approaches that simulate roughness by triggering transition, we include a wall-roughness model to capture physical erosion effects. We demonstrate that clean-turbulent simulations cannot accurately reproduce performance degradation due to leading-edge erosion, whereas our roughness-based approach allows for reliable performance scaling in mixed polars. Based on two proposed erosion-robustness criteria, we optimized a new family of 21% and 30% thick airfoils targeting operation at a Reynolds number of 12 million. Optimizations produced highly cambered airfoils with significant performance gains. The new 21% airfoil improves the lift-to-drag ratio by 50 counts (clean, free transition) and 16 counts (P40 eroded) over the FFA-W3-211 reference. While matching the OSO-21-WT2 in eroded performance, it offers a thicker trailing edge and broader performance peak in clean free transition, enhancing manufacturability and stability. The new 30% airfoil outperforms the FFA counterpart by 28 counts (clean, free transition) and 9 counts (eroded), and the OSO reference by 37 counts (clean) and 8 counts (eroded). These findings highlight that explicitly modeling surface roughness is critical for developing erosion-robust wind turbine blades.