An Investigative Study on Energy Harvesting by Hydrofoils: Simple vs. Undulated

A series of experiments were performed using multiple configurations of hydrofoils to assess the energy harvesting capabilities present within the wake of streamlined bodies. The experiments were performed in a low-speed water tunnel, with energy harvesting assessed using a piezoelectric eel and imaging equipment. Half-sinusoidal undulations were introduced in different combinations on the leading and trailing edges of the hydrofoil. All hydrofoils utilized a NACA 0012 cross-sectional profile. A piezoelectric eel was placed at a variable distance downstream of the hydrofoil’s trailing edge, and the hydrofoil’s angle of attack (α) was varied in order to assess the variation in power generation. The maximum power output was achieved at x/c = 1–1.5 downstream of the trailing edge in all configurations. It was observed that harvested energy is dependent on the oscillation of the eel, α, the streamwise distance between the trailing edge of the hydrofoils and the eel, as well as the geometry of the hydrofoils. Particle image velocimetry was also performed on selected cases for which the recorded energy harvest was high. The results showed that the NACA 0012 base profile has a higher extractable energy capacity in its wake than do the serrated hydrofoils, which confirms the results found in the literature.