Effect of uniformly varying width leading-edge slots on the aerodynamic performance of wind turbine blade

Abstract

According to the Betz limit, the maximum wind power that can be extracted from wind is limited to 59 %. Practically it stands at a 30–40 % level. Therefore, current research targets to increase the aerodynamic performance of wind turbines by introducing uniformly varying width (UVW) leading-edge slots. In present work, a UVW narrow channel is deployed using NACA (National Advisory Committee for Aeronautics) 4412 aerofoil, which starts from the leading-edge region and goes away to the pressure side of the aerofoil after a slight bending. NACA 4412 aerofoil is chosen as it has the highest lift to drag ratio. Six wind turbine blades of different dimensions (Gradually increasing Wi/Wo ratio) are proposed. Six proposed wind turbine blades are designed and analysed using CFD (computational fluid dynamics) with 0° to 16° at a 2° increment. Wind speed is taken at 7 m/s as per Indian conditions. Out of six proposed blade designs, NACA 4412 aerofoil (Wi/Wo = 2) gives 12 % spike lift to drag ration than the uniform slotted one. Again NACA 4412 aerofoil (Wi/Wo = 2) performs at its peak at angle of attack (AOA) 6°. It is observed that interaction of fluid separation zone and slot inlet results in a down grade of the aerodynamic performance of wind turbine blade. A scaled-down (one-fifth) model of the superior blade (made up of wood) and Solid blade have been made for the wind tunnel test and comparison. The computational results were compared from a series of wind tunnel tests.