Abstract: In order to improve the energy extraction efficiency of an oscillating hydrofoil, an oscillating hydrofoil structure with trailing edge flaps was proposed. This structure was to install a trailing edge flap at the rear end of a traditional hydrofoil, and used the swing of the trailing edge flap to achieve the purpose of increasing power. The equations of motion of flap oscillations were established and the equivalent angle of attack equation was derived. The model was numerically simulated using the dynamic and moving grid technologies in the CFD software. The simulation results showed that the trailing edge flap structure increased the arch of the hydrofoil and increased the attack angle of the hydrofoil, which in turn increased the lift coefficient and the time-averaged power coefficient. The derived equivalent angle of attack formula was consistent with the simulation results, and the equivalent angle of attack formula can better predictd the simulation results. The negative work of the trailing edge flap occupied a small proportion of the total power collected by the oscillating hydrofoil.

Key words: tidal energy, oscillating hydrofoil, trailing edge(TE)plain flap, energy harvesting, hydrodynamic