水动力段塞流激发的混合立管振动响应

海洋立管是输送海上油气至生产平台的关键装备,面临油气两相流诱导振动的风险。本文通过建立气液两相循环系统,开展了不同气液比水动力段塞流作用下的混合立管流致振动响应实验研究,采用高速摄像同步捕捉了管道振动位移及管内气液两相流动特征。实验发现:柔性跳接管平面内振幅及管内液塞长度随气液比的增大而增大,模态切换更为频繁。柔性跳接管的主导振动频率与长液塞流动频率和压力波动频率吻合。刚性立管的摆动频率也参与了柔性跳接管的振动,但其影响沿管轴方向不断衰减,且随气液比的增大而减弱。

段塞流诱导柔性立管振动响应实验分析

在气液两相循环实验系统中开展了水动力段塞流诱导的悬链线型柔性立管振动响应测试,利用高速摄像非介入测试方法同步捕捉了柔性立管的振动位移与管内的段塞流动细节,预测了气体表观流速对水动力段塞流诱导柔性立管振动响应的影响规律,分析了振幅响应、模态权重、频谱变化以及管内流动特性。结果表明,随着气体表观流速的增大,振动幅度逐渐增大,模态交互作用逐渐增强,尽管高阶振动模态权重不断增大,但一阶模态在立管振动响应中始终占据主导;对于较小的气体表观流速,振动响应主要归因于短段塞的不稳定流动,对于较大的气体表观流速,振动响应主要取决于长段塞的流动频率;气体表观流速增大使管内流动速度、段塞长度逐渐增大,而持液率逐渐减小。

水动力段塞诱导的柔性立管振动响应实验研究

柔性立管作为海洋油气开采连接海床与海面的关键纽带,发挥着至关重要的作用,但也面临着内部油气段塞流诱发的振动威胁。该文实验研究了水动力段塞流诱导的柔性立管振动响应,利用高速摄像非介入同步采集柔性立管的振动位移及管内两相流动特性。实验发现:柔性立管的振动主要发生在平面内,且两个方向的振动相互关联;两个方向的模态转换在时间上同步,但在空间上存在差异性;柔性立管的振动幅度与管内通过的液塞长度有关,而模态转换与管内段塞单元的重现频率有关。

Experimental study on pressure fluctuation characteristics of slug flow in horizontal curved tubes

In order to study the pressure characteristics of slug flow in horizontal curved tubes,two kinds of curved tubes with central angle 45° and 90° respectively are studied,of which are with 0. 5m circumference and 26 mm inner diameter are used. When the superficial liquid velocity or the superficial gas velocity is constant,the pressure fluctuations and the probability distribution of the average velocity of slug flow are clear for all of the five experimental conditions. The results of experiment show that the pressure characteristics of slug flow in curved tubes have periodic fluctuations. With the rise of central angle,the period of pressure fluctuation is more obvious. The system pressure of the slug flow increases with the increasing of superficial liquid/gas velocity. Meanwhile,the probability distribution of pressure signal shows regularity,such as unimodal,bimodal or multimodal.