Numerical and experimental studies of airfoils suitable for Vertical Axis Wind Turbines and an application of wind-energy collecting structure for higher performance

Numerical simulations and wind tunnel experiments were carried out to study airfoils and a wind-energy collecting structure (wind-lens) suitable for Straight Wing Vertical Axis Wind Turbines (SWVAWT). The aim of this study is to increase the output power coefficients of SWVAWT. The numerical method is a direct numerical simulation (DNS) based on the finite difference method. The results of DNS revealed that symmetry airfoils are better than asymmetry airfoils for the output performance. In the wind tunnel experiment, the results of output performance test showed that the best airfoil is NACA0024. We designed a wind-lens and applied it to SWVAWT. In the wind tunnel experiments, the output power coefficients of SWVAWT with a wind-lens were more than 2 times as large as those of a SWVAWT only. We made clear the effect of the wind-lens on the output performance by DNS.