Energy-harvesting performance of a fully-passive coupled-pitching hydrofoil: A numerical study

Abstract

A fully-passive coupled-pitching hydrofoil is a developing trend for tidal-current power capture in the future. A two-dimensional numerical model was established to investigate the hydrodynamic characteristics and energy-harvesting performances of the hydrofoil under this operating mode, which was validated by corresponding experimental data. A benchmark case with a successful self-starting and stable working state was proposed. Effects of the Reynolds number, initial angle of attack, and primary moment of inertia on the operating mechanism of the hydrofoil were studied with the analysis of the flow structure around the hydrofoil and pressure and torque distributions. The variations of these parameters significantly influenced the generation of the leading-edge vortex, resulting in different phase differences between the primary and secondary passive pitching motions. The power coefficient and energy-harvesting efficiency peaked at 0.57 and 0.22, respectively.