Aeroacoustic investigation of a modified horizontal axis wind turbine blade

This study presents a computational analysis of an NREL phase-VI HAWT blade, incorporating a winglet at the tip of the blade, inspired by its use in aircraft. An aeroacoustic analysis is conducted on baseline and winglet blades across varying wind speeds and receiver locations using the FW-H model, with results validated against reference data. The unsteady flow characteristics reveal that pressure differences at the blade tip form vortices, winglets weakens and confines these vortices closer to the tip, reducing energy-dissipating turbulence and improving aerodynamic performance. Velocity helicity, which measures fluid flow’s swirling characteristics, indicates that the base blade generates higher helical flow patterns at the blade tip compared to the winglet blade. The reduced helical patterns with the winglet suggest decreased rotational energy losses, improving power generation. Quantitatively, the winglet blade exhibits higher normal force coefficients across the blade span, with the most significant improvement observed near the tip (i.e. 95% of the radial location of the blade). Increasing wind speed results in higher overall sound pressure levels due to increased turbulence and blade-tip noise, with observed increases ranging from 6.4% to 9.6%. Blade design significantly influences wind turbine noise, with winglet blades reducing aerodynamic noise by decreasing vortex intensity, resulting in 6.9% to 8.1% lower OASPL compared to baseline blades. Noise emission from the HAWT varies with the downstream receiver locations, the results show that the noise-reduction effect of the winglet blade persists across all measured positions, demonstrating its spatial robustness. Overall, the findings highlight the potential of winglets to reduce aerodynamic noise while improving flow characteristics near the blade tip.