Numerical study on vortex induced vibration of hydrofoils with trailing-edge truncation

Abstract

Vortex-induced vibration of hydrofoils may cause structural damage and noise hazards to engineering applications under certain unfavorable conditions. Therefore, the vortex-induced vibrations of a hydrofoil under different conditions should be investigated in detail. In this paper, numerical simulations are conducted to study the vortex-induced vibration characteristics of an elastically suspended hydrofoil with trailing-edge truncation. The vibration responses under various structural natural frequencies are calculated. In addition, the effect of six trailing-edge truncation angles from 0° to 40° on the vibration characteristics is explored. Results indicate that the hydrofoil experiences frequency lock-in within a specific frequency range, where structural motion controls vortex shedding patterns and the vortex shedding frequency locks into the structural natural frequency. Moreover, as the trailing-edge truncation angle increases, the upper threshold of frequency lock-in decreases, but the lower threshold shows a first decreasing and then increasing trend, with the minimum value at 30°. Simultaneously, there exists an optimal truncation angle to minimize vibration amplitude at a certain structural natural frequency. The wake flow analysis demonstrates that the vibration amplitude reduction is due to the spatial shift between the vortex detachment locations of upper and lower surfaces, leading to the collision of vortices and energy dissipation.