Abstract:
The purpose of this study is the energy harvesting by using piezoelectric eel behind two cylinders in side by side arrangement. The improvement in power generation by vibrations caused by vortices is studied by performing a series of water-tunnel experiments. Two side by side cylinders in a staggered arrangement, with varied center-to-center gaps are placed in the water tunnel with the fluid flowing uniformly and electrical power is obtained using the vibrating behavior of the piezoelectric eel caused by vortices in the downstream region. Distance was varied in 𝐺𝑥 and 𝐺y both to check the behavior of flag. The poor and optimal coupling of different flapping modes with wake flow is observed in the experimental results. It is also demonstrated that the streamwise distance between the fixed end of piezoelectric eel and the line joining the centers of the staggered cylinders, and the center-to-center gap between cylinders have a significant effect on the flapping frequency and amplitude, resulting variation of the output power of piezoelectric eel. The experiments are carried out for cylinder diameter, 𝐷 = 25 𝑚𝑚 and flag length, 𝐿 = 60 𝑚𝑚 resulting 𝐿/𝐷 = 2.4. Different cases with varying 𝑁/𝐷 values from 1.00 to 2.00 for different values of 𝐺𝑥 from 1.5 to 3.0 and for 𝐺y from 0.5 to 2 were tested. During these studies, the comparison of Power, Amplitude and Frequency at each point for all the cases were made to understand the effects of systems variable and their trends. The optimal power is achieved for N/d=1 and its value is 68.01 µW. As we move from N/d=1 to N/d=2, the power is reduced by 25.4%. When N/d=1, it means both cylinders are attached to each other and the vortex developed by both converges at a point (𝐺𝑥 =3.0, 𝐺y =0.5) and the harvested power is increased. As we move from N/d=1 to N/d=1.25, their vortex initiation region goes away from each other and they can’t meet so frequently at a point. As N/d is further increased, the power goes to decrease because their vortex doesn’t converge with each other. This study makes an effective contribution to the field of energy harvesting from striking vortices by setting the streamwise distance and center-to-center distance gap the staggered cylindrical bluff bodies.
