Investigating the Performance of a Small Horizontal Axis Wind Turbines (HAWT) Using Toroidal Blades

Abstract Optimizing the aerodynamic design of small-scale horizontal-axis wind turbine (HAWT) blades is essential for enhancing annual energy production, performance, and efficiency. This study employs Computational Fluid Dynamics (CFD) with the ANSYS FLUENT solver to investigate the aerodynamic behavior of a newly designed multi-bladed HAWT, specifically introducing toroidal blades. The primary objectives include understanding the aerodynamics of two and three-bladed toroidal rotors, improving HAWT performance by increasing the power coefficient (Cp) and identifying the optimal looping ratio (C) for elliptic toroidal blade shape. The research involves a detailed comparison between toroidal and conventional turbine blades, utilizing Blade Element Momentum (BEM) theory and a NACA 4412 airfoil for blade sections. The geometry characteristics, such as chord length and twist, are carefully calculated along the blade. A 3D geometric domain is created and appropriately meshed for the rotor. Analysis is conducted on a model representing the rotor at a constant wind speed of 7 m/s and various Tip Speed Ratios (TSR). A parametric study for the toroidal blade focuses on the shape ratio (C), determining the optimum ratio as 0.25. The results reveal a notable 14% increase in the power coefficient (Cp) for the three-bladed toroidal blade, calculated based on the optimum TSR for both basic and toroidal blades. The findings suggest that toroidal blades can effectively enhance small HAWT performance, especially at lower TSR. Overall, this research highlights the potential of toroidal blades to improve the power coefficients of small-scale HAWTs.