Abstract
A two-dimensional (2D) wave-current numerical flume and fully activated hydrofoil numerical model were established to investigate the effects of traveling waves on the energy-harvesting performance of a flapping hydrofoil tidal current energy (TCE) device. The hydrodynamic and energy-harvesting performances of the hydrofoil were investigated under various conditions, including wave heights (0–1.8 times the chord length), pitching amplitudes (40°–80°), submerged depths (3–18 times the chord length), and frequency ratios (0.5–1.5). To reveal the underlying mechanisms of the wave effects, the flow field structures, hydrodynamic lift and torque were analyzed, along with energy-harvesting performance. Both the efficiency and power coefficient increased with increasing wave height and decreasing submerged depth. Compared with other frequency ratios, the hydrofoil achieved optimal energy harvesting efficiency across a broad range of pitching amplitudes when the frequency ratio was 1.0. Maximum efficiency and power coefficient values of 0.42 and 1.02, respectively, were obtained when the wave height was 1.8 times the chord length, submersion depth was 3 times the chord length, and pitching amplitude was 60°. Base on the water particle velocity distribution in the wave theory, the enhanced energy-harvesting performance is primarily attributable to the increased angle of attack induced by wave effects.