Abstract:
A set of experiments are performed in two-dimensional wave flume to investigate the energy harvesting from phase-locked and non-phase-locked modes of vortex in deep water waves by using flexible piezoelectric eel in a controlled oceanic environment. Flapping dynamics of the eel in the wake of circular cylinder at different wave conditions is studied. Energy harvesting potential is examined as a function of streamwise distance from fixed cylinder and spanwise gap along the cylinder at different wave conditions. It is observed that output voltage and eel flapping behaviour are highly dependent on cylinder vortices caused by local wavelength and wave amplitude. Maximum energy is harvested when eel is placed near to the surface caused by high flapping amplitude and frequency. Similarly, at greater depth low flapping amplitude is observed resulting in small output voltage. Maximum output voltages are found at shorter wavelength and at streamwise distance of Gx=1.25 for all spanwise gap along the cylinder and minimum voltages are calculated at longer wavelength and at streamwise distance Gx= 0.75. An increase of 65% in energy harvesting is observed by switching longer wavelength (λ) to shorter one and changing piezo-eel spanwise gap from deep depth to shallow depth. Whereas, an increase of 31.5% was found by keeping wavelength constant and changing spanwise gap of eel. Furthermore, it is observed that energy harvesting from the wake of a bluff body in wavy motion of water is sensitive to the wavelength and wave height. In this study, the effect of wave and geometrical parameters on energy harvesting is studied extensively and proposed that maximum energy harvesting can be achieved by fine tuning of streamwise distance Gx, spanwise gap Gy, wavelength λ and wave height H.
