Investigation of the Synergetic Effect of Using J-shaped Profile and Winglets in Single and Multiple Profile Blades of Small-scale Horizontal Axis Wind Turbines

The design of wind turbine blades plays a significant role in determining the aerodynamic performance of the rotor. In this study, the effect of using different blade design modifications for small-scale horizontal axis wind turbines (HAWTs) was investigated. Experimentally generated wind power was used for the Computational Fluid Dynamics (CFD) validation on the lab scale, and experimental laboratory wind speeds and Tip Speed Ratios (TSRs) were used to run CFD simulations. The synergetic effect of combining two blade design modifications (winglets and pressure-side J-shaped truncation) was investigated. This study focuses on the average power coefficient enhancement for different wind speeds. Furthermore, the effect of using the same design modifications was studied for multiple-profile HAWT blades using profiles with high thickness-to-chord ratios near the hub. Combining the two design modifications and their effects on single- and multi-profile HAWT blades has not been addressed in the literature. This study aims to fill these gaps. It was found that adding the one-third pressure-side J-shaped truncation (J(1/3)) to the winglet cases enhanced the power coefficient and produced a synergetic effect on the overall power coefficient. Furthermore, the J(1/3) pressure-side truncation was found to be more effective for multiple-profile HAWTs. At the same time, the negative 30° cant angle downstream winglet (N30) and the combination of winglet N30 with J(1/3) provided better performance for the single-profile HAWTs.