Bio-Inspired Owl Airfoils for Improved Aerodynamic Performance of Small-Scale Wind Turbines

Abstract This study investigates the aerodynamic performance of a set of owl-inspired airfoil geometries and their application to a horizontal-axis wind turbine blade. An owl-wing-derived baseline airfoil was first modified through a systematic geometric transformation to generate multiple variants with adjusted thickness distributions while preserving the original camber characteristics. Two-dimensional numerical simulations were conducted over a range of low Reynolds numbers representative of small-scale wind turbine operation to evaluate lift, drag, and flow separation behaviour. The results highlight distinct aerodynamic trends among the proposed airfoils, particularly in terms of lift development, drag growth, and the onset and progression of flow separation on both suction and pressure sides. To assess blade-level implications, the OA-T airfoil was implemented near the tip region of the well-documented NREL Phase VI blade as a case study, and three-dimensional simulations were performed under multiple inflow velocities. The modified blade exhibited a consistent increase in torque relative to the baseline configuration, with the performance gap becoming more pronounced at higher wind speeds. Flow field analysis using velocity streamlines revealed altered near-tip flow structures that help sustain aerodynamic loading under increased inflow conditions. Overall, the findings demonstrate the potential of owl-inspired airfoil concepts to influence both airfoil-level and blade-level aerodynamic performance, particularly in low-Reynolds-number and tip-dominated flow regimes.