Numerical investigation into the effect of the trailing edge shape on added mass and hydrodynamic damping for a hydrofoil

摘要

Engineering applications prove that the modification of the trailing edge shape of a blade can effectively reduce the amplitude of the vortex-induced vibration, but the mechanism behind it is still not fully understood. In this investigation, unsteady CFD and two-way FSI numerical simulation methods are performed on three-dimensional (3D) NACA 0009 hydrofoils with blunt and Donaldson trailing edges. The vortex shedding formation process, the added mass and the hydrodynamic damping ratio at different flow velocities are investigated. The relative deviations in the vortex shedding frequency, the natural frequency in water, and the hydrodynamic damping ratio obtained by simulation are within 12.88%, 4.62% and 8.82%, respectively, compared with the experimental results. As the flow velocity increases, the added mass for blunt and Donaldson trailing edge hydrofoils remains almost constant and gradually decreases, respectively. The hydrodynamic damping ratio of the hydrofoil increases linearly as the flow velocity increases with both blunt and Donaldson trailing edges involving a slope of 0.0032 and 0.005, respectively. At a flow velocity of 20 m/s, the maximum amplitude is reduced to 57% after Donaldson trailing edge modification. The results show that the hydrodynamic damping ratio of the Donaldson trailing edge is significantly increased when the flow velocity is greater than 20 m/s. The reason for this is the collision between the upper and lower trailing edge vortexes, which leads to the faster dissipation of vortex intensity. (C) 2019 Elsevier Ltd. All rights reserved.