带齿圆柱体结构是自升式平台桁架式桩腿的一种典型结构形式，研究这种刚性细长结构物的流致振动现象对于减少平台的疲劳损伤具有指导意义。基于计算流体力学方法（CFD），采用重叠网格技术研究了弹性支撑柱体在不同来流角度下的流致振动响应，得到振动幅值、频率、运动轨迹和涡泄模式。其中，来流角度范围为0°~90°，约化速度U_r范围为3~30。结果表明：0°、15°、75°、90°时，主要振动类型为涡激振动（VIV）；30°时，U_r=8~16的振动类型为涡激振动与驰振竞争，其余约化速度下的振动类型为涡激振动；45°和60°时，低约化速度的振动类型为涡激振动，高约化速度的振动类型为驰振，但60°发生驰振所需的约化速度比45°低。结构发生涡激振动时，运动轨迹以“8”形和倾斜的“0”形为主；驰振时呈现出倾斜的“弓”形；在涡激振动和驰振共存时呈现出无序的状态。当结构关于来流不对称时，易发生驰振，驰振周期远大于涡脱落周期。一个驰振周期内会产生多个单涡，结构向上、下运动过程中涡脱落的个数并不相同，力与位移并不同步，涡的脱落决定了势能分量，势能分量的方向和大小决定了结构相对初始平衡位置的偏移方向和大小。

英文摘要:

The toothed cylinder is a typical structural form of the truss pile leg for a jack-up platform. The investigation of the flow-induced vibration phenomenon of this rigid slender structure is instructive for reducing fatigue damage to the platform. Based on CFD and using overset grid technology, the flow-induced vibration response of an elastically supported cylinder at different inflow angles has been studied, and the vibration amplitude, frequency, motion trajectory, and vortex shedding patterns are obtained. The inflow angle ranges from 0° to 90°, and the reduced velocity U_r ranges from 3 to 30. The displacement amplitude, vibration frequency, motion trajectory, and wake mode were obtained. The results show that the main vibration mode is vortex-induced vibration (VIV) at 0°, 15°, 75°, and 90°. At 30°, the dominant vibration mode is a coexistence of VIV and galloping under U_r=8~16, while VIV dominates at other reduced velocities. At 45° and 60°, the vibration mode is VIV at low reduced velocities and galloping at high reduced velocities; however, the reduced velocity required for galloping to occur at 60° is lower than that at 45°. When the structure undergoes VIV, the motion trajectory mainly takes the form of an “8” shape and an inclined “0” shape. In the case of galloping, it exhibits a tilted “bow” shape. When VIV and galloping coexist, the motion becomes disordered. When the structure is asymmetric with respect to the incoming flow, galloping tends to occur. The galloping period is much longer than the vortex shedding period, and multiple single vortices can be generated within one galloping cycle. The number of shed vortices differs during the upward and downward motion of the structure, and force and displacement are not synchronized. Vortex shedding determines the potential energy component, whose direction and magnitude dictate the offset of the structure from its initial equilibrium position.

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