海冰载荷是严寒海区近海风力机面临的主要载荷之一,具有作用力大、持续时间长和振动特性复杂等特点,对风力机结构尤其是塔架的动态响应具有严重影响.为研究海冰载荷对风力机影响,采用NREL 5 MW近海3叶片水平轴风力机为研究对象,基于Kaimal风速谱建立湍流风场,采用自激冰振模型和FAST程序,计算海冰载荷作用下风力机塔基剪切力,得出结论:因海冰强度“负坡段”,风力机受海冰作用在中低冰速时会发生自激振动;自激振动造成了塔基剪切力显著增加,增幅随冰厚增加而减少;塔基前后向剪切力波动高于侧向;海冰载荷造成塔顶位移在1.1Hz附近幅值增加.%Sea-ice load is one of the main loads of offshore wind turbines in severe cold sea regions,it has features of large action force,lasting as long and complex vibration characteristics.It has great influences on dynamic responses of wind turbines,especially,the tower of wind turbines.To study influences of sea-ice load on wind turbines,a NREL 5 MW offshore wind turbine was taken as a study object.Based on Kaimal wind speed spectrum,a turbulence wind field was built.The self-excited ice induced vibration model and FAST program were adopted to calculate shear forces exerted on the tower base of the turbine under the action of sea-ice load.The results showed that due to the "negative slope" of sea-ice strength,the wind turbine performs a self-excited vibration under the action of sea-ice with low or medium ice velocity;the self-excited vibration makes shear forces exerted on the tower base of the turbine grow obviously,their increasing level decreases with increase in thickness of sea-ice;shear forces' fluctuation in tower base forward-backward direction is bigger than that in tower base left side-right side direction;sea-ice load leads to increase in the tower top displacement amplitude near 1.1 Hz.
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