基于尾流振子模型的套管涡激振动响应研究

针对PIP （Pipe In Pipe）系统（套管）的涡激振动问题，开展了对PIP系统在涡激振动作用下的动力学响应研究，分析了在涡激振动作用下不同无因次波数、内外管道直径比、连接层刚度以及张力对海洋立管位移响应的影响规律。研究基于Euler-Bernoulli双梁理论，采用尾流振子模型，建立了动力学模型，利用谐波平衡法求得内、外管道的振动响应表达式。结果表明，在不同无因次波数的作用下，套管的振动存在不稳定现象，在七阶模态时，管道的振动出现单一频率的振动现象；在高频率比区域，随着无因次连接层刚度的增大，内、外部管道的位移均呈现先减小后增大的趋势，并且逐渐趋于稳定；张力对外部管道位移的影响相对复杂，内部管道的位移随张力的增大呈现减小的趋势。

Response Study of Vortex-induced Vibration of PIP System Based on Wake Oscillator Model

The study on the dynamic response of the PIP system under the effect of vortex-induced vibration is carried out for the vortex-induced vibration of the pipe-in-pipe system. The effects of different dimensionless wave numbers, inner and outer pipe diameter ratios, joint layer stiffness, and tension on the displacement response of the marine riser under the action of eddy excitation vibration are also analyzed. In the study, based on the Euler-Bernoulli double-beam theory and using the wake oscillator model, a dynamics model is established, and the expressions of the vibration response of the inner and outer pipes were obtained using the harmonic balance method. The results show that there is instability in the vibration of the PIP under the action of different dimensionless wave numbers and that the vibration of the pipe appears to vibrate at a single frequency in the seventh-order mode. In the high-frequency ratio region, with the increase of the dimensionless connection layer stiffness, the displacements of both internal and external pipes show a trend of first decreasing and then increasing, and gradually stabilizing. The effect of tension on the displacement of the external pipe is relatively complex, and the displacement of the internal pipe shows a decreasing trend with the increase of tension.