The vortex-induced vibration may lead to a premature failure of hydraulic mechanical systems, especially under the resonance condition in the torsional mode. To predict the structural fatigue life, a careful consideration of the dynamic response to the hydraulic excitations is essential in the design phase. This study focuses on the numerical investigation of the relationship between the flow velocity, the added mass and the hydrodynamic damping, particularly, with respect to a Donaldson-type hydrofoil, vibrating in the first torsional mode. A two-way fluid-structure interaction (FSI) method is used to predict above two parameters. The flow velocity is in the range of 0 m/s–20m/s. To evaluate the hydrodynamic damping ratio, an identification method is proposed, based on a modified version of the logarithmic decay method. The relative deviations of the simulated natural frequencies and hydrodynamic damping ratios as compared with the experimental data for the first torsional modes, are within 8.1% and 16.6%, respectively. The analysis results show that the added mass coefficient for the first torsional mode is in the range of 1.59–1.86, and is around 44% of that for the first bending mode. The trends of the boundary layer thickness and the wake width against the reduced velocity are found to be opposite to that of the hydrodynamic damping ratio. The theoretical equation for predicting the hydrodynamic damping ratio is modified, which is shown to be more reliable due to its consideration of the velocity independent hydrodynamic damping phase.

涡流引起的振动可能会导致液压机械系统过早失效，尤其是在扭转模式下的共振条件下。为了预测结构疲劳寿命，在设计阶段必须仔细考虑对液压激励的动态响应。这项研究的重点是数值研究流速，附加质量和流体动力阻尼之间的关系，特别是对于以第一扭转模式振动的唐纳森型水翼。双向流体-结构相互作用（FSI）方法用于预测以上两个参数。流速在0 m / s–20m / s的范围内。为了评估流体动力阻尼比，基于对数衰减方法的改进版本，提出了一种识别方法。与第一扭转模态的实验数据相比，模拟固有频率和流体动力阻尼比的相对偏差分别在8.1％和16.6％之内。分析结果表明，第一扭转模式的附加质量系数在1.59–1.86范围内，约为第一弯曲模式的附加质量系数的44％。发现边界层厚度和尾流宽度相对于减小的速度的趋势与流体动力阻尼比的趋势相反。修改了用于预测流体动力阻尼比的理论方程，由于考虑了与速度无关的流体动力阻尼相位，因此该方程更加可靠。