Lifting-Surface Theory for Multi-Wing Configurations of Elastically Supported Flapping Wing Power Generator

The analytical method based on the lifting-surface theory for calculating power and efficiency of the multi-wing cascade configurations of an elastically supported flapping wing power generator is presented. The theoretical results of the power and efficiency for the single, two-wing and three-wing configurations are presented, and the effects of distance between the wings, the oscillation mode (in-phase and anti-phase mode) and aspect ratio on the power and efficiency are clarified. For the single and two-wing configurations, the theoretical results are compared with the experimental data obtained for a hydroelectric power generator, and reasonable agreement of the theory and experiment is obtained. For the effect of aspect ratio, it is shown that the increments of power and efficiency for the middle wing of the three-wing configuration in anti-phase mode of oscillation that are expected by increasing the aspect ratio from three to ten are approximately 61% and 43% at the wing distance of 1.5 chords, respectively.