Novel hybrid blade design and its impact on the overall and self-starting performance of a three-dimensional H-type Darrieus wind turbine

The present study proposes a novel hybrid blade design that is the combination of a con-ventional airfoil, namely the NACA0018, and its J-shaped profile to increase the torque generation at the start-up stage of the turbine while decreasing the potential efficiency loss at the high tip speed ratios. Therefore, a new 2D-based design methodology was proposed, and depending on this methodology, different hybrid blade configurations were determined for the investigation of the overall and self-starting performance of the H-type Darrieus vertical axis wind turbine. Due to the inherent shape of the proposed hybrid blade, a 3D CFD dynamic start-up model, which is based on the fluid- turbine interaction, was built and used to evaluate the performance of the different configurations of the hybrid blades. The results indicate that although the proposed design methodology is based on the 2D-CFD calculations, it enables a quicker prediction of the aerodynamic performance of the proposed hybrid blades compared to the 3D -based CFD simulations. Furthermore, the findings also clearly illustrate that the new proposed hybrid blade designs not only overcome the self-starting issue of the turbine but also provide a wider turbine operating range and an improvement in the turbine peak efficiency in contrast to the losses caused by J-shaped airfoils.(c) 2023 Elsevier Ltd. All rights reserved.