BIOMIMETIC MICROSPIKE ENHANCEMENT OF H-ROTOR DARRIEUS WIND TURBINE PERFORMANCE: AN EXPERIMENTAL INVESTIGATION

Abstract

The H-Rotor Darrieus vertical-axis wind turbine (VAWT) offers advantages for distributed energy generation but it unfortunately also suffers from poor low-wind-speed performances due to its aerodynamic inefficiency. On the other hand, there is an opportunity to apply biomimetic flow control strategies that have been inspired by the natural systems for passive performance enhancement without mechanical complexity. Taking this into account, this study investigates the application of the dragonfly-inspired microspikes to the turbine blades of a H-Rotor Darrieus wind turbine. In this study, the small-scale prototype H-Rotor Darrieus wind turbine with NACA 4415 airfoil blades has been designed and fabricated using additive manufacturing process. The microspikes are positioned at 30% chord from the leading edge of the blades to generate boundary layer vortices. The resultant performance effect of the microspikes is tested outdoor with uncontrolled environment and compared with baseline blades. Overall, the results have demonstrated an increase of approximately 18.5% in blade rotation, 22% in torque coefficient, 18.7% in tip speed ratio and also almost 0.5% in both wind power and power output.  This is taken to show that the blades with microspike vortex generators have the potential to re-energize the boundary layer, delay flow separation and significantly increase lift and reduce drag. Furthermore, the power output capacity and aerodynamic efficiency of the H-Rotor Darrieus wind turbine are shown to significantly increase with the microspike vortex generators attached to its airfoil blades.