On the geometrical effect of vertical axis wind turbine on its aerodynamic output

Renewable energy resources are becoming more attractive for sustainable energy development globally. Wind energy has a significant potential as an alternative energy source as a result of the effects of global modernization. Over the years, the demand for a small-scale wind turbine in built environments has increased to reduce urban areas' carbon emissions. Vertical axis wind turbine (VAWT) has development potential because VAWT is suitable for low wind speed condition, high turbulence, and wind direction variations. However, these wind rotors generally have lower efficiency. The current number of studies and publications and the basic understanding of VAWT under unfavorable conditions are limited. Based on the literature reviews, two relevant factors of the critical parameters that positively impact the VAWT power performance are the aspect ratio and solidity. Therefore, a comprehensive numerical analysis has been conducted in this study to understand the aerodynamic phenomena and wind flow characteristics around turbine's blades that influence the VAWT's performance with different aspect ratios and solidities in low Reynolds number conditions (100000, 150000 and 200000). The numerical investigation was carried out using ANSYS Fluent software using high-fidelity Computational Fluid Dynamics (CFD) technology. Current research employs various aspect ratios (0.4, 2.0 and 4.0) with rotor radii of (2.50 m, 0.50 m, and 0.25 m), respectively and with a different chord length of air foil which is (0.1 m and 0.20 m). The blade height was fixed at 1.0 m to achieve various solidity. For low Reynolds numbers of wind conditions, a two-dimensional CFD model of H-Darrieus VAWT with different solidities was simulated corresponding to TSR values (2.0, 2.5, 3.0). Various computational settings in CFD simulation are considered based on previous studies' experiences and data. For verification purposes, the initial results were compared and validated against published simulation and experimental data to ensure the accuracy of the simulation results obtained in this study. This research also consists of 54 simulations in total. This study aims to provide an overview and understanding of the effect of changes in rotor diameter on VAWT power performance and a preliminary review for future research into improving the optimal VAWT design for urban areas