Vortex-assisted figure-eight wing power system

Due to the rising demand for low-cost clean energy, the development of efficient wind and water energy-generating systems is one of the major goals of this century. A novel approach for extracting energy efficiently from wind and water currents utilizes a tail-weighted wing following a figure-eight trajectory. Our prototype consists of a vertical ribbon-type wing suspended at its endpoints by swivel bearings. Energy is extracted from the longitudinal pumping motion that occurs at the endpoints of this flexing wing. Since the forces in these wings are in tension like a suspension bridge, the design can potentially be scaled up to much larger sizes than current systems and sweep across enormous areas of moving fluid with a relatively small amount of material. High-speed photography is used to map out the trajectory of a prototype wing and to monitor water flow around the wing. These observations along with data from an interactive computer simulation program are used to study the vortices and hydrodynamic forces that propel the wing along the figure-eight trajectory. Our prototype is low-cost, simple to fabricate and extracts a high amount, 30%, of the total energy in the water that flows through it.