天然气管道跨越结构在两相流突变激振力作用下的清管动力响应研究

Strong vibrations are the main dynamic behavior of natural gas pipeline aerial crossing (NGPAC) during the pigging process. Its driving force is induced by the gas-liquid two phase pigging column. Based on the experimental records, the magnitude of the exciting force may suddenly change during the pigging process. Under the condition of pigging velocity beyond 5 m/s, the sudden-change exciting force may cause unexpected explicit as well as over stress of NGPAC. The project plans to study the mechanism and variation regulation of this two phase flow induced vibration by using both the theoretical and experimental methods. Firstly, using the exiting suspension and cable-stayed NGPAC experiment platform, two experiments will be conducted in order to learn the inner relationship among the two-phase flow, structure dynamic behavior and the sudden-change exciting force. Secondly, based on the experiment data, the simulation model of sudden-change exciting force will be established in accordance with the multiphase flow mechanism, structure mechanics and flow induced vibration theory. Third, a new dynamic response model for NGPAC will be built with combination of the sudden-change exciting force model. Fourth, the solution of the model will be obtained by the weak coupled method, numerical method and finite element method. The dynamic behavior of NGPAC during pigging process will be analyzed based on the model and its solution. The achievements of this project will provide good theoretical and technical guidelines for design, operation and safety management of NGPAC.

天然气管道跨越结构在清管时出现的强振动，是由清管气液两相流动激发的流致振动。实验研究表明，清管速度超过5m/s时会产生显著的气液两相流突变激振力，导致跨越结构失稳和应力超限。采用理论与实验相结合的方法，研究考虑突变激振力的流致振动机理与跨越结构动力响应规律。基于悬索和斜拉索式管道跨越结构室内实验平台，探究两相流流动、管道动力响应特征与突变激振力之间的内在联系与变化规律；应用多相流理论、结构力学和流致振动理论，建立清管两相流突变激振力流致振动力学模型，以及管道跨越结构清管动力响应数学模型；基于弱耦合原理、数值分析方法与有限元技术探究模型的求解方法，分析两相流突变激振力作用下管道跨越结构的清管动力响应规律。为天然气管道跨越结构的设计、运行和安全管理提供理论与技术支持。

针对天然气管道跨越结构在清管速度达到5m/s及以上时，可能经历多次激振后的复杂强振动和大位移过程的问题，采用实验与理论相结合的方法，开展了跨越结构在两相流突变激振力作用下的清管动力响应研究。（1）基于相似原理，搭建了悬索与斜拉索跨越结构的两相流突变激振力测试实验平台，开展了90组工况条件下的清管动力响应实验，明确了突变激振力的产生机理及其影响因素，建立了考虑突变激振力条件下跨越结构清管变形曲线计算公式。（2）基于动量守恒、质量守恒以及管道挠曲线方程，考虑两相流突变激振力来源于管道变形与清管器运行的耦合作用机理，以管道位移为耦合变量，以清管器与计算点之间的相互位置关系为判定标准，建立了考虑两相流突变激振力的清管载荷计算模型。（3）考虑天然气管道跨越结构的几何非线性因素，建立了非线性静力分析方程，以缆索的初始应变为迭代参数，结合有限元方法，实现了模型求解。（4）以跨越结构的静力分析模型为基础，结合结构的动力微分方程，将考虑突变激振力的清管载荷作为节点力进行加载，建立了天然气管道跨越结构考虑两相流突变激振力的动力响应模型。（5）以实验获取的考虑突变激振力条件下跨越结构清管位移的经验计算公式为计算初值，以管道位移为迭代参数，采用预测-校正法结合有限元技术，实现了动力响应模型的求解。（6）以勐岗河悬索跨越结构、南广河斜拉索跨越结构为实例，对动力响应模型进行了实例验证，成功实现了对突变激振力作用下的位移波动的模拟，通过将计算结果与实验结果进行对比发现，悬索跨越结构管道的位移偏差在-3.54%至2.05%间，平均相对偏差为-1.08%；斜拉索跨越结构的管道位移平均相对偏差为0.23%，验证了清管动力响应模型的准确性与适用性，为天然气管道跨越结构的安全清管提供了理论依据与数据基础。