Effects of solidity on the vibrational characteristics of the LEP VAWT

The primary goal of this research is to explore the influence of structural responses brought about by alterations in aerodynamic characteristics resulting from the incorporation of leading-edge protuberance (LEP) blades in vertical-axis wind turbines (VAWTs). A scaled-down straight-blade VAWT was utilized and subjected to operational wind speeds at a fixed pitch angle and various blade configurations to carry out this investigation. The study specifically aimed to investigate the unsteady structural excitation caused by the decay of vortices due to different aerodynamic loads and their effects on the VAWT structure. The results demonstrated that counter-rotating vortices in the LEP profile enhanced the aerodynamics of the blades at higher angles of attack. Understanding the structural characteristics resulting from aerodynamic changes is essential for developing VAWTs. The current research analyzes the effects of LEP on the structural excitation of a VAWT by examining the acceleration and displacement data obtained from a static-structure VAWT for various solidity ratios and LEP profiles. The results indicated that the VAWT with LEP blades resulted in decreased acceleration and displacement amplitudes for a low solidity ratio, which increased with an increase in the solidity ratio. Significant aerodynamic and structural damping were observed in the VAWT with LEP blades. These results were in close agreement with the time and frequency domains of the measured displacement and acceleration of the structure. The average bi-directional vibration damping of approximately 35% was observed by substituting the straight blade with the LEP blades for the operation of VAWT.