为提升半潜式风机稳定性，在其支撑平台底部安装垂荡板，但垂荡板边缘引起的尾涡脱落导致其水动力非线性特征显著。准确评估垂荡板的非线性水动力特性对风机响应预报至关重要。以底部安装垂荡板的OC4-DeepCwind半潜式风机平台为研究对象，考虑半潜式风机显著的低频运动特征，基于计算流体力学方法，在时域下探究低频运动对半潜式风机垂荡板水动力特性的影响。实际工程计算垂荡板水动力载荷时应关注水动力系数在低频运动与波频运动下的显著不同。结果表明，垂荡板纵荡阻尼系数随周期变化趋势与上立柱不同，运动周期越大，纵荡阻尼系数对于KC数的变化越敏感。KC数小于1时，运动周期接近风机平台纵荡固有周期下的阻尼系数相对于波频运动下的阻尼系数增长显著，最大增幅达30%；当KC数大于1时，运动周期不再对阻尼系数产生影响。垂荡板的垂荡附加质量系数和纵荡附加质量系数均随运动周期增大而增加，特别是周期接近风机平台纵荡固有周期时，纵荡附加质量系数相对于波频运动下的附加质量系数增幅达34%。

英文摘要:

To improve the stability of semi-submersible wind turbines, heave plates are installed at the bottom of their support platforms. However, the vortex shedding caused by the edges of the heave plate results in significant nonlinear hydrodynamic characteristics. Accurate evaluation of these nonlinear hydrodynamic characteristics is crucial for predicting the turbine's response. This study focuses on the OC4-DeepCwind semi-submersible wind turbine platform with a heave plate installed at the bottom, considering the significant low-frequency motion characteristics of the semi-submersible wind turbine, Based on computational fluid dynamics (CFD) methods, the impact of low-frequency motion on the hydrodynamic characteristics of the heave plate is investigated in the time domain. In practical engineering calculations of hydrodynamic loads on the heave plate, it is important to consider the significant differences in hydrodynamic coefficients under low-frequency motion and wave-frequency motion. The results show that the trend of the heave plate's surge damping coefficient with period differs from that of the upper columns. As the motion period increases, the surge damping coefficient becomes more sensitive to changes in the KC number. When the KC number is less than 1, the damping coefficient at the wind turbine platform's surge natural period increases significantly compared to the damping coefficient under wave-frequency motion, with a maximum increase of up to 30%. When the KC number exceeds 1, the motion period no longer affects the damping coefficient. Both the heave plate's heave added mass coefficient and surge added mass coefficient increase with the increase of motion period, especially when the period is close to the natural surge period of the wind turbine platform. In this case, the surge added mass coefficient increases by up to 34% compared to the added mass coefficient under wave-frequency motion.

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