Energy harvesting properties of a flapping foil with blow aspirators: A numerical investigation

Abstract

In recent years, researchers have worked hard to improve the efficiency of energy collection devices because a better use of renewable energy is required for energy protection and emission reduction. To improve the energy harvesting efficiency of a flapping wing, this study proposes a blower model for the first time. By installing blower aspirators at the rear of the upper and lower wing surfaces of an airfoil, this airfoil can achieve higher lift and torque than the original airfoil. This study was performed under a Reynolds number Re=1100 and focused on the impact of the attenuation frequency, the effective angle of attack, and a fixed selection of optimal blower speeds. The unsteady laminar two-dimensional numerical simulation results show that there is an optimal working area on the upper and lower airfoil blowers under the given working conditions, and the energy collection efficiency increases when the upper and lower airfoil blowers have similar speeds. For different attenuation frequencies and effective angles of attack, the optimal blower speed improved by 10%, with the highest being 26.7%. Through a flow field analysis, the vortex of the flapping wing equipped with a blower was found to be closer to the airfoil than the vortex of original airfoil at different times and it had a higher vortex intensity than the original. Choosing a reasonable blower velocity can help to capitalize on the blower’s ability to increase lift and torque, and thus improve the efficiency of a flapping wing.