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Dynamic characteristics and stability of pipe-in-pipe system conveying two-phase flow in thermal environment
Applied Ocean Research ( IF 4.3 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.apor.2020.102333
Yang Guo , Bo Zhu , Xiang Zhao , Bo Chen , Yinghui Li

Abstract Pipe-in-pipe (PIP) systems are utilized widely in modern petroleum industry owing to their good insulation effect. In present work, a novel mathematical model for the free vibration of the fluid-conveying cantilevered PIP system considering thermal effect and two-phase flow is proposed. The insulation layer connecting two concentric pipes is simplified as the distributed springs and dampers here. The governing equation of the pipe system is then derived using Hamilton's principle based on Euler-Bernoulli beam theory. Then the Galerkin method is applied to the free vibration analysis. In the numerical section, parametric analysis is performed to elucidate the effects of different physical factors, such as environment temperature, equivalent stiffness and damper of the insulation layer, structural damping, two-phase flow, and axial load on the dynamic characteristic and stability of the PIP system through the forms of Argand diagram, stability map, and time history diagram. The results show that the PIP system has an advantage over a single fluid-conveying pipe in terms of stability considering thermal effect, axial load, and structural damping. Besides, different from single pipe, two different frequencies are found for each vibration mode, and two-pipe coupled flutter instability occurs to the PIP system as the fluid velocity exceeds the critical fluid velocity. The theoretical work is helpful to improve the analysis and design of the PIP system with consideration of internal two-phase flow and environmental temperature.

中文翻译:

热环境下输送两相流的管中管系统动态特性及稳定性

摘要 管中管(PIP)系统因其良好的保温效果而在现代石油工业中得到广泛应用。在目前的工作中,提出了一种考虑热效应和两相流的流体输送悬臂式 PIP 系统自由振动的新数学模型。连接两根同心管的保温层在这里简化为分布式弹簧和阻尼器。然后使用基于欧拉-伯努利梁理论的哈密顿原理推导出管道系统的控制方程。然后将Galerkin方法应用于自由振动分析。在数值部分,通过参数分析阐明不同物理因素的影响,如环境温度、绝缘层等效刚度和阻尼器、结构阻尼、两相流、通过Argand图、稳定性图和时程图的形式,分析和轴向载荷对PIP系统的动态特性和稳定性的影响。结果表明,考虑到热效应、轴向载荷和结构阻尼,PIP 系统在稳定性方面优于单个流体输送管。此外,与单管不同的是,每种振动模式都有两个不同的频率,当流体速度超过临界流体速度时,PIP系统会出现双管耦合颤振不稳定。理论工作有助于改进考虑内部两相流和环境温度的PIP系统的分析和设计。结果表明,考虑到热效应、轴向载荷和结构阻尼,PIP 系统在稳定性方面优于单个流体输送管。此外,与单管不同的是,每种振动模式都有两个不同的频率,当流体速度超过临界流体速度时,PIP系统会出现双管耦合颤振不稳定。理论工作有助于改进考虑内部两相流和环境温度的PIP系统的分析和设计。结果表明,考虑到热效应、轴向载荷和结构阻尼,PIP 系统在稳定性方面优于单个流体输送管。此外,与单管不同的是,每种振动模式都有两个不同的频率,当流体速度超过临界流体速度时,PIP系统会出现双管耦合颤振不稳定。理论工作有助于改进考虑内部两相流和环境温度的PIP系统的分析和设计。当流体速度超过临界流体速度时,PIP 系统发生双管耦合颤振不稳定。理论工作有助于改进考虑内部两相流和环境温度的PIP系统的分析和设计。当流体速度超过临界流体速度时,PIP 系统发生双管耦合颤振不稳定。理论工作有助于改进考虑内部两相流和环境温度的PIP系统的分析和设计。
更新日期:2020-10-01
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