为研究半潜式平台的涡激运动特征，进行了水槽模型试验研究。测试了流向角为0°、15°、30°及45°时，在不同来流速度下半潜平台的横荡、纵荡及艏摇运动响应；并以艏摇运动为重点，从响应幅值、运动频率等角度出发，探讨其涡激运动的关键特征。结果表明：在不同来流方向情况下，半潜式平台均未发生明显的频率锁定现象。当流向角为0°和15°时，平台三自由度响应随约化速度的增加近似呈线性增大的趋势；当流向角为30°和45°时，在约化速度4~10附近平台响应出现了明显的共振现象，并在此现象结束后响应大幅减小，之后，随着约化速度的增加再次大幅增大。除个别工况外，艏摇与横荡均高度耦合，其响应频率主峰值基本保持1:1关系；艏摇固有周期对平台三自由度运动频率及幅值影响均不明显。流向角为45°时，平台的艏摇运动最为剧烈，在各个约化速度下响应幅值均数倍于其他流向角。另外，在0°流向角时观察到了“驰振”现象；15°流向角的多个约化速度下观察到了“自激”现象。
Abstract
Here, in order to study vortex-induced motion (VIM) features of a semi-submersible platform, its flume model tests were conducted. The motion response amplitudes and frequencies of its sway, surge and yaw motions were measured under different incoming flow velocities and flow angles of 0 °, 15 °, 30 ° and 45 ° to explore key characteristics of its VIM. The results showed that there is no obvious frequency locking phenomenon in different incoming flow directions; the platform’s 3-DOF response almost linearly increases with increase in reduced velocity when the flow angle is 0 ° and 15 °; the platform’s response has resonance phenomenon when the flow angle is 30 ° and 45 ° and the reduced velocity (Ur) is close to 4~10, and the response significantly decreases after the resonance phenomenon is over, then it sharply increases again with increase in reduced speed; except under few working conditions, the platform’s sway and yaw motions are highly coupled and their response frequencies’ main peaks remain the relation of 1∶1; the natural period of yaw has almost no effect on the platform’s 3-DOF motion frequency and amplitude; when the flow angle is 45°, the platform’s yawing motion is the most strenuous, its response amplitude is several times of those for other flow angles at any reduced speed; in addition, galloping phenomenon is observed when the flow angle is 0°; self-excitation phenomenon is observed when the flow angle is 15 ° at multiple reduced speeds.
关键词
半潜式平台、涡激运动、艏摇、频率、响应幅值
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Key words
semi-submersible platform /
vortex-excited motion /
yaw /
frequency /
response amplitude.
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