Performance Enhancement of Fully Active Corrugated Flapping Foil Flow Energy Harvester

Abstract

Alternate means of energy harvesting, such as application of bio-inspired systems is an active area of research and has evolved as a novel design model. Birds and insects inspired Flapping foils exhibit substantially improved aerodynamic performance as compared to static wings. Formation of Leading edge vortex (LEV) and low pressure within, play fundamental part in higher instantaneous lift generation. In this study, numerical simulation of a Fully Active flapping foil energy harvester subjected to sinusoidal pitching and heaving motion is conducted to examine aerodynamic performance and efficiency. Analysis was carried out on a corrugated (dimpled) airfoil, which assists in timely travelling and development of leading edge vortex resulting in improved energy extraction performance. The airfoil is externally excited to undergo sinusoidal pitching and heaving motion at low Reynolds number (Re=1100). The net energy extraction can be accomplished under the effect of time changing fluid forces. ANSYS Fluent ® is employed to analyze the separation bubble travelling based on wavelength and amplitude at prescribed sinusoidal pitching and heaving motion with particular frequency and phase difference. The results indicate that corrugations (dimples) on the airfoil helps in timely travelling and growth of leading edge vortex. Moreover, the sinusoidal pitching motion improves the creation of leading edge vortex accompanied by harmonization of vertical velocity and vertical force by elevation of vertical force peak value. Corrugated (dimpled) airfoil exhibits early separation of flow and stronger LEV formation.