Numerical investigation into energy extraction from self-induced oscillations of an elliptical plate

Abstract

A new concept of power generator using self-induced oscillating foil to extract energy from fluid is proposed and tested in the present study. The pitching motion of the elliptical foil is induced by the downward shed vortexes of the foil. Two-dimensional Navier-Stokes simulations at Re=104 are conducted to study the fluid-foil interaction as well as the performance of energy extraction. Three kinds of motion trajectories are concerned, i.e. pitching motion, pitching motion combined with streamwise plunging and pitching motion combined with transverse plunging. The investigations are undertaken over a wide range of structural parameters (mass ratio, stiffness factor and damping coefficient). Numerical results reveal that the pitching motion combined with transverse plunging can achieve best energy extraction performance. With well-tuned structural parameters, the power generator can reach maximum power coefficient of 32% and energy extraction efficiency of 20%. Hence, it demonstrates that the promising self-induced oscillating foil can achieve satisfactory energy extraction performance without pitching motion actuator.