A novel elli-circ oscillator applied in VIVACE converter and its vibration characteristics and energy harvesting efficiency

Based on the phenomenon of flow-induced vibrations, harnessing ocean currents for power generation is a relatively novel approach. In comparison to other technologies, it is particularly well-suited for deployment in regions characterized by low flow velocities. However, in the case of deep-sea environments with extremely low flow velocities, there is a need to identify an appropriate cross-sectional for oscillators that can effectively generate power through FIV. To address this problem, This paper proposes a novel Elli-Circ cross-sectional oscillator model, which couples a semi-ellipse with a semi-circle. Numerical simulations are conducted to analyze the FIV characteristics and energy harvesting capabilities of this oscillator under different radius ratios and mass damping ratios. The study reveals that compared to other cross-sectional oscillators, the Elli-Circ cross-sectional oscillator experiences an initial increase and subsequent decrease in vibration amplitude with the increase of reduced velocity. The amplitude peak occurs at lower flow speeds, and the vibration frequency continues to increase. The Elli-Circ oscillator exhibits superior vibration characteristics at extremely low flow velocities (U ≤ 0.4 m/s). for the case of a radius ratio R/r = 1.6, damping ratio ζ = 0.12, and mass ratio m* = 1.001, the Elli-Circ oscillator achieves its maximum energy harvesting power of 0.39 w. Additionally, the highest energy conversion efficiency of 16.77% is obtained for ζ = 0.12 and m* = 1.343. Therefore, the Elli-Circ cross-sectional oscillator coupled with a semi-ellipse and semi-circle exhibits superior energy harvesting characteristics at extremely low flow speeds (U ≤ 0.4 m/s) and high damping ratios.