A fully-activated flapping foil in wind gust: Energy harvesting performance investigation

The energy harvesting performance of a fully-activated flapping foil under wind gust conditions is numerically investigated in this work. A NACA0015 airfoil performs the imposed heaving and pitching motions. The wind gust is modeled as a single frequency harmonic oscillation, and there is a phase difference between the wind gust and the pitching motion of the foil. To conduct numerical computations, the commercial code FLUENT together with the dynamic mesh strategy are adopted. At a Reynolds number of 1100 and the position of the pitching axis at one-third chord, the effects of the gust frequency, the oscillation amplitude of gust, and the phase difference between the gust and the pitch are systematically examined. By comparing with the results from the uniform flow, it is found that the energy harvesting efficiency under wind gust conditions can be changed greatly. Particularly, when the phase difference is in the range of 90 and 270, a higher energy harvesting efficiency is produced, which is attributed to the increased lift force as well as the good synchronization between the lift force and the heaving velocity.