Experimental Study on the Influence of Groove-Flap and Concave Cavity on the Output Characteristics of Vertical Axis Wind Turbine

To address the low wind energy utilization efficiency of vertical axis wind turbines (VAWTs) and enhance their engineering applicability, cavity and groove-flap structures were incorporated into turbine blades. Numerical simulations were performed to optimize these configurations, followed by wind tunnel experiments investigating output power variations of three VAWT types under different wind speeds at installation angles of 0°, 2°, 4°, and 6°. The Omega criterion was employed to comparatively analyze vortex evolution patterns at the leading and trailing edges for installation angles of 0°, 3°, and 5°. Experimental results demonstrated nonlinear growth in output power with increasing wind speed and rotational velocity, with groove-flap VAWTs exhibiting superior performance. The optimal installation angle was identified within 2.5–3.5°, where appropriate angles reduced adverse pressure gradients, delayed boundary layer separation, and mitigated vortex shedding effects. Excessive angles induced vortex accumulation and wake disturbances, compromising flow field stability. This study provides critical insights for optimizing VAWT aerodynamic performance through structural modifications and installation angle adjustments.