Effect of aspect ratio on the performance of an enhanced Archimedes spiral wind turbine in urban conditions

• The performance of an ASWT prototype was improved through geometric modification • The proposed model requires reduced cut-in wind speeds to initiate rotation • The proposed ASWT offers a slightly increased capacity factor in urban environments This study presents an improved design of an Archimedes Spiral Wind Turbine to enhance its aerodynamic performance and suitability for urban energy harvesting. The novelty of this work lies in the systematic evaluation of the aspect ratio in combination with other geometric parameters, such as the number of blades, spiral configuration, opening angle, and blade orientation, to quantify their influence on rotor efficiency under low-wind and urban flow conditions. The turbine prototypes were assessed through free-air flow experiments and subsequently validated in a subsonic open-circuit wind tunnel, complemented by numerical simulations to characterize flow behavior and torque performance. The results demonstrate that the enhanced wind turbine achieves a 30% reduction in cut-in wind speed and attains a 22% higher rotational speed than a reference design documented in the literature. Numerical analyses further indicate a 12% increase in aerodynamic torque, highlighting improved flow guidance achieved through the modified spiral geometry. These findings confirm that optimizing the aspect ratio and blade configuration significantly enhances the energy capture potential of spiral wind turbines.