Study on stall behavior of a straight-bladed vertical axis wind turbine with numerical and experimental investigations

Abstract

This paper presents a straight-bladed vertical axis wind turbine (VAWT) model for the evaluation of the stall phenomenon associated with unsteady flow around the airfoil surface with numerical and experimental investigations. In wind tunnel experiments, in order to investigate flow visualization, light-weight tufts attached to the inner surface of blade are used to gain insight on the flow characteristics of VAWT during rotation in the low Reynolds numbers. In numerical analysis, a 2D computational investigation on the stall phenomenon and aerodynamic characteristics at the VAWT airfoil is associated with the standard κ−ε model and Shear Stress Transport κ−ω (SST κ−ω) turbulence model. And then, the stall behavior is validated according to compare the results of wind tunnel experiment and numerical analysis. From this study, it is concluded that the numerical simulation captures well the vortex-shedding predominated flow structure which is experimentally obtained and the results quantitatively agree well with the wind tunnel experimental data. Moreover, the flow separation behavior of the airfoil shows the importance of stall phenomenon and the interaction of the separated vortex with the blade as mechanisms in lift and drag coefficients.