Dynamic stall of vertical-axis-wind-turbine rotor blades equipped with Gurney flaps and vortex generators

Abstract

There are many important aerodynamic phenomena on vertical axis wind turbines. Particularly relevant is flow separation that causes structural fatigue and adversely affects self-starting characteristics of VAWTs at lower wind velocities. Passive flow-control devices on VAWTs rotor blades have been commonly studied to mitigate these adverse characteristics. While there are many studies on this topic, the dynamic stall characteristics of VAWTs rotor blades equipped with Gurney flaps (GFs) and vortex generators (VGs) are not completely clear. It is accordingly the goal of the present study to investigate the aerodynamic performance of the NACA 0021 airfoils in the angle of attack range from 0º to 360º. The experiments were performed in a wind tunnel using rotor blade equipped with VG and GF devices. Experimental results encompass aerodynamic force and moment coefficients of the NACA 0021 airfoil equipped with VGs and GFs. These devices proved to improve the aerodynamic characteristics of the NACA 0021 airfoil and to reduce the adverse effects of flow separation.