The prediction of hydrodynamic damping characteristics of a hydrofoil with blunt trailing edge

Abstract

Flow-induced vibration is a prevailing phenomenon in the operation of the hydraulic machinery system. Fluid-structure interaction (FSI) is an important characteristic of flow-induced vibration and must be taken into account in design phase of hydraulic machinery. FSI in the form of mass loading and damping, it has a major impact on the dynamic response of the structural. Hydrodynamic damping can reduce the vibration amplitude and improve the stability of the hydraulic machinery which is of great importance. The aim of this study is to prediction the hydrodynamic damping characteristics of a NACA 0009 hydrofoil by using three dimensional two-way fluid-structure interaction modeling. The first bending mode of the hydrofoil is excited to produce the deformation, then the deformation information is transmitted to the flow field through the fluid-solid coupling junction. In the numerical simulation, dynamic response is acquired by dynamic mesh deformation of flow field, and the hydrodynamic damping parameters are obtained by the logarithmic decay method. Turbulent viscosity is computed by using the two equation SST k-ω model and the effect of time step on the calculated results is eliminated. It was found that the hydrodynamic damping is significantly increased linearly as the flow velocity is increased, and this trend is consistent with the experimental results. The results of this research are compared with those obtained from experiments and the relative difference is around 50% by least squares linear regression, and it is essential to consider the effect of numerical damping and near-wall region processing on the results.