Comparative study of theoretical and numerical analysis to evaluate the aerodynamic performance of a helical vertical axis wind turbine

Abstract

This study investigates the aerodynamic performance and self-starting capability of helical vertical axis wind turbines (VAWTs) using both Q-Blade and ANSYS simulation software, emphasizing small-scale urban wind energy solutions. Key design parameters such as helix angle, solidity, aspect ratio, and blade pitch were systematically varied across 75 rotor designs. Two rotor configurations, a non-tapered NACA0018 and a tapered NACA0020 were selected using Q-Blade parametric analysis. Further Computational Fluid Dynamics (CFD) simulations were conducted for the two models in ANSYS Fluent. Q-Blade simulations identified optimal models based on Cp (Power coefficient) and starting torque, while CFD analysis revealed significant differences arising from three-dimensional flow effects, such as dynamic stall and vortex interactions. The tapered NACA0020 rotor demonstrated improved self-starting performance and reduced torque ripple, making it more suitable for small scale applications, despite the NACA0018 achieving a slightly higher Cp in idealized conditions. The validated CFD results highlighted the limitations of Q-Blade, which overestimates the Cp values due to lesser complexity in the solving models in the Q blade software. Both designs exhibited stable performance in low tip speed ratio (TSR) ranges, ideal for turbulent, low-wind environments. These findings support the practical implementation of helical VAWTs and recommend further experimental validation.