Performance enhancement of Archimedes spiral wind turbines via gurney flap parametric analysis: A numerical and experimental study

The Archimedes Spiral Wind Turbine (ASWT), despite being an innovative horizontal-axis design for urban energy harvesting, is plagued by poor efficiency. To improve the performance of ASWT, a novel Gurney flap (GF) enhanced ASWT configuration is proposed and the GF geometric effects on ASWT's aerodynamic performance are investigated using experimental and computational fluid dynamics (CFD) approach. Key findings indicate that narrow GFs (2%-3%) show minimal angle sensitivity, slightly improving starting torque and power performance across all tip-speed ratios with consistent gains over the original ASWT. In contrast, wide GFs (4%-10%) require large angles (>150°) to mitigate adverse drag effects and enhance power output, while also extending the tip-speed ratio operational range. The 165° GF angle with a 6%-7% width is identified as the best configuration, boosting the maximum power coefficient by 14% while maintaining self-starting capability. Flow field analysis confirms that this configuration promotes favorable pressure distribution, suppresses flow separation and vortex formation, and reduces energy dissipation. Conversely, small-angle and wide-GF combinations induce severe flow separation, increasing drag and degrading performance. By highlighting the critical interplay among parameters for GF optimization in ASWTs, this work provides important guidance for the future development of high-performance ASWTs suited to urban settings.