内输多相流与绕流耦合作用下立管非线性振动

Nonlinear vibration of a riser under inter-action between internal multi-phase flow and cross flow

对内输多相流立管在内流与外部绕流耦合作用下的振动响应进行了分析。建立了内部多相流-立管-外部绕流的耦合方程,并采用广义积分变换法(GITT)将偏微分方程转化为常微分方程进行求解。分析得到立管内两相流会引起立管自然频率的降低,管内流速越高,立管越长,两相流作用越明显;立管在内流和外部绕流共同作用下,管内含气量的增加,使立管发生涡激振动的频率降低,振动幅值增加;管内两相流的作用会引起立管在较小的外部流速下发生共振并且会诱发立管发生更高一阶模态的振动;外部绕流流速越高,管内两相流作用越小。

The dynamic response of a riser conveying multi-phase flow under interaction between internal flow and external cross flow was analyzed.The internal multi-phase flow-riser-external cross flow coupled dynamic equations were established,and they were solved through transforming partial differential equations into ordinary ones with the generalized integral transform technique(GITT).The results showed that the internal two-phase flow causes the riser’s natural frequencies to drop;the higher the internal flow rate and the longer the length of the riser,the more significant the internal two-phase flow’s action;under the interaction of internal flow and external cross flow,increase in gas content inside the riser makes the frequency of the riser’s vortex induced vibration decrease and the vibration amplitudes increase;internal two-phase flow causes the riser’s resonance under a lower external flow rate and induces the riser’s higher order modal vibration;the higher the external cross flow rate,the smaller the action of internal two-phase flow.