ENERGY HARVESTING BY VORTEX-INDUCED VIBRATIONS OF STRUCTURES WITH DIFFERENT CROSS-SECTIONS

The shape of the structure plays a crucial role in determining its vibration characteristics, such as the amplitude and frequency of vibration. The purpose of this investigation is to explore how the flow-induced vibration behavior and energy harvesting potential are impacted by the cross-sectional shape of a structure. In this work, the cross-sectional shapes of the bluff body considered are circular, square, diamond, and triangle. The reduced velocity (Ur) is varied in the range of 2 - 12. The mass ratio is taken as 1.7, and the damping ratio as 0.016. The hydraulic diameter for all the shapes is kept constant, and the Reynolds number based on the hydraulic diameter is varied in the range of 1.7x10(4) to 10.3x10(4) to mimic the flow velocity of the water current in the ocean (0.19 - 1.14 m/s). In this work, water is considered as the flowing fluid, which is supposed to be incompressible and viscous. The flow dynamics of the fluid over a bluff body are described using the unsteady Reynolds Averaged Navier-Stokes equations, and the turbulence is modeled through the SST k-omega turbulence model. Based on the findings, it can be concluded that the shape of the bluff body has a significant impact on both the vibration characteristics, the output power, and the efficiency of energy harvesting. The analysis suggests that circular shapes are ideal for energy harvesting from flow-induced vibrations at low Ur, while diamond shapes are most suitable at high Ur. In this study, the maximum output power of 1.57 W was obtained with a diamond-shaped structure at Ur = 10. Whereas the maximum efficiency of 9.01% was obtained through the circular structure at Ur = 4.