Abstract
This paper presents a comprehensive numerical investigation of the aerodynamic performance of a three-bladed vertical-axis Darrieus wind turbine equipped with asymmetric airfoil blades, with the primary aim of evaluating the influence of blade geometry on torque generation and overall aerodynamic efficiency. The study focuses on a detailed analysis of rotor flow behavior, including the spatial distributions of velocity and pressure fields, the formation and evolution of flow separation zones, and the development of a turbulent wake structure downstream of the rotor over a wide range of operating conditions. Numerical simulations were carried out using the Reynolds-Averaged Navier–Stokes equations coupled with the k–ω SST turbulence model, which provides reliable prediction of near-wall flow behavior, adverse pressure gradients, and unsteady aerodynamic effects typical for vertical-axis wind turbines. The obtained results demonstrate that the asymmetric blade profiles interact more effectively with the incoming airflow at moderate tip speed ratio values, leading to improved torque characteristics and a noticeable reduction in negative torque regions. In particular, the maximum average torque coefficient was observed at tip speed ratio values close to 2.5, where the aerodynamic performance of the rotor reached its optimum due to balanced lift and drag forces acting on the blades. At higher tip speed ratio values, despite the stabilization of the flow structure and reduction of large-scale vortical formations, a decrease in aerodynamic efficiency was identified, and the findings of this study provide a scientific basis for optimizing blade geometry and selecting efficient operating regimes in the design of Darrieus-type vertical-axis wind turbines with asymmetric airfoils.