Numerical investigation on effect of leading-edge deformation to alleviate dynamic stall of pitching airfoil in unsteady flow

Abstract

Dynamic stall is a serious phenomenon that restricts aeronautical vehicles’ maneuverability. It happens on the blades as their angle of attack increase, especially on the blade of wind turbines. In this paper, two airfoils are investigated in actual conditions. To alleviate dynamic stall the geometries of the airfoils are modified by drooping and rounded leading-edge tip method and also combination of both. To study the effect of the modifications, the unsteady flow fields around the pitching airfoils, numerically simulated using URANS. Results illustrates, in addition to alleviate dynamic stall, the methods enhance aerodynamic characteristics by reducing drag force and preventing sudden jump of lift force, especially at the maximum angle of attack. Finally, a detailed investigation is conducted on the flow behavior around the airfoil to discover the supporting physics behind the improvements made by the present methods. Which revealed that these two passive methods, aim to prevent the formation of leading-edge vortex on the airfoil which finally delays the dynamic stall.