防台钻井隔水管脱离状态下振动响应模型试验

防台钻井隔水管近海面脱离后的振动特性关系到实际的生产安全。通过模型试验对其脱离状态下的振动特性进行研究。试验结果表明:脱离后,由于隔水管上端自由度得到释放,雷诺数较低时,其振动形态表现为刚性体自激振动的振型;随着雷诺数的增大,其振动响应中同时存在弹性支撑刚性体的自激振动和两端连接柔性管的模态振动,体现为主次频的关系;随着雷诺数的进一步增大,主次关系发生转变,对应于振型的转变;顺流向与横流向上的振型转变并不同步,顺流向上的振型转变需要更大的流速;相比于正常连接状态,脱离后的振型分布有向隔水管上端移动的趋势。

Model Test on Vibration Response of Storm-safe Drilling Riser after Disconnecting

The vibration characteristics of the storm-safe drilling riser after disconnecting are related to the actual production safety. In this paper, the vibration response in this special condition is analyzed by the model test. The results show that after disconnecting, due to the release of the upper end of the riser, the vibration mode of the riser performs like the elastic support rigid body dose when the Reynolds number is low. With the increase in Reynolds number, the self-excited vibration of the elastic support rigid body and the modal vibration of the flexible tube simultaneously exist in this special condition presenting from the primary and secondary frequency. With the further increase in Reynolds number, the status between the primary and secondary frequency exchanges which corresponds to the transformation of the vibration mode. The transformation of the vibration mode in in-line direction and cross-flow direction are not synchronous, that in the in-line direction requires a larger flow rate. Compared with the connection state, the vibration mode distribution trends to move up to the top of the riser after disconnecting.