Compliant membranes to augment the performance of oscillating foil energy harvesting systems

Oscillating Foil Turbines (OFT) take advantage of the strong transient lift forces generated by vortices formed at the leading edge when the hydrofoil operates at a large pitch angle. Membrane wings inspired by flying and gliding mammals such as bats and flying squirrels have been shown to stabilize leading edge vortices and here we explore the use of membranes to augment the performance of OFTs. Compliant membrane wings with varying Aeroelastic number - the ratio of inertial to elastic stresses - were tested in a open surface water tunnel, and their performance is compared with that of inextensible membranes and rigid foils over a range of pitching frequencies, heave and pitch amplitudes.