Wingmill: An Oscillating-Wing Windmill

Abstract

This article describes an analytical and experimental investigation of a windmill which utilizes a harmonically oscillating wing to extract wind energy. In particular, the wing's span is horizontally aligned and the airfoil is a chordwise-rigid symmetrical section. The whole wing oscillates in vertical translation and angle-of-attack, with prescribed phasing between the two motions. A theoretical analysis was developed utilizing unsteady-wing aerodynamics from aeroelasticity and the results guided the design of a working model for wind-tunnel experiments. For the cases tested, theory and experiment compared favorably, and showed the wingmill to be capable of efficiencies comparable to rotary designs.