Parametric analysis on the frequency lock-in phenomenon of an elastic hydrofoil

Vortex-induced vibration (VIV) of hydrofoils is a pivotal concern in the field of ocean engineering. This study performs a parametric analysis on VIV of an elastic hydrofoil, specifically focusing on the vortex shedding frequency, trailing edge vibration and vortex intensity. The effects induced by vortex shedding are captured through combining the finite volume solid stress method and the Shear Stress Transport (SST) k-omega model. Frequency domain analysis of the hydrodynamic coefficients is conducted using the fast Fourier transform (FFT). Based on extensive convergence study, the effects of oncoming velocity, thickness, and the angle of attack are investigated in detail. The results show that the trailing edge thickness or relative thickness of the hydrofoil can be adjusted to avoid excessive vibration when the lock-in phenomenon occurs. It is also found that the influence of angle of attack on lock-in vibration primarily lies in the shedding of the trailing vortex. It can be attributed to the forward movement of the transition position of the boundary layer on the upper trailing edge of the hydrofoil, leading to an earlier separation of the boundary layer.