Flow-Induced Response Mechanisms and Energy-Harvesting Characteristics of a Novel Circular-T-Attachment Oscillator

A novel circular-T-attachment (CTA) oscillator is proposed to improve the oscillation response and energy-harvesting performance. This combined section is designed to change the boundary layer separation and avoid vortex reattachment, effectively enhancing energy conversion in the galloping branch. Results indicate that in the vortex-induced vibration (VIV) branch, the harvested fluid energy increases with reduced velocity. As system damping increases, the oscillatory response transitions from soft galloping (SG) to hard galloping (HG), indicating a progressive weakening of the self-excited transition to galloping. Within the tested parameter range, the galloping branch provided the most favorable energy-conversion performance. The maximum amplitude ratio reached 2.43, while the maximum active power and energy conversion efficiency (ECE) reached 19.3 W and 26.2%, respectively. Compared with a conventional triangular prism oscillator at the same reduced velocity, the proposed CTA oscillator achieved increases of 9.29 W in active power and 12.59 percentage points in energy conversion efficiency. These results clarify the flow-induced response mechanism of the circular-T-attachment oscillator and provide new insights for improving the performance and expanding the application range of flow-induced motion energy conversion systems (FIMECSs).