摘要
输流管道常用于石油天然气行业中,管道内过高流速会引发结构失稳,因此掌握输流管道临界流速的计算方法至关重要。受热荷载作用下的输流管道也经常被应用于实际工程领域中,比如加热输送的原油管道和供暖管道等。热荷载作用下的输流管道相比于基本输流管道受到热荷载作用引起的轴力,其自然振动频率及临界流速与普通输流管道存在一定的差异。基于哈密顿原理推导得到热荷载作用下两端支承输流管道的振动偏微分方程,通过分离变量将方程简化为一元四次齐次常微分方程。根据两端支承输流管道临界流速条件简化微分方程并求得其通解,给出了适用不同边界条件的输流管道临界流速解析表达式。基于算例分析了不同边界条件下线性热应力和非线性热应力对输流管道临界流速的影响,并与微分求积计算方法的结果进行对比,验证了给出的解析计算方法的准确性。研究表明相对于微分求积法,提出的解析方法计算更加简单,准确性更高,可以更方便的得到输流管系统的临界流速值,有利于指导工程实践;线性热应力和非线性热应力作用下的输流管系统的临界流速均随着热荷载的增加而降低,且下降速度越来越快;同等情况下非线性热应力作用下临界流速大于线性热应力作用下的临界流速,且随着热荷载的增加,两者间的差距逐渐增大;对比边界条件发现,固定边界条件能够承受的热荷载最大,因此对热荷载作用下输流管系统施加固定边界条件有利于提高系统的稳定性。本文提出的热荷载作用下输流管道临界流速的解析方法在工程现场可以方便快速地得到准确的临界流速,为热荷载作用下输流管道系统的设计和安全评价提了参考依据。
Pipes conveying fluid play an important role in the oil&gas industry.It is critical to determine the critical velocity for structural stability design and safety evaluation of these pipes.Pipes conveying fluid under thermal load are also often used in practical engineering fields,such as crude oil pipeline heating transportation and heated pipelines.Compared with the basic pipes conveying fluid,the natural vibration frequency and critical velocity of a pipeline under thermal load are different from those of the basic pipeline.Based on Hamilton’s principle,the partial differential equation of vibration of supported pipes conveying fluid under thermal loads is derived and the equation is reduced to a univariate fourth-order homogeneous ordinary differential equation by separating variables.A general solution is obtained according to the critical flow velocity conditions of supported pipes conveying fluid.Furthermore,the analytical solutions of the critical velocity are obtained considering various boundary conditions.Finally,numerical examples are presented for analyzing the influence of linear thermal stress and nonlinear thermal stress on the critical velocity under various boundary conditions.The predictions using the proposed analytical solution are compared with results using the differential quadrature method available in the literature.It is demonstrated that the proposed analytical solution can give an accurate solution efficiently,which can be used in engineering practice.The critical flow rate of the pipes conveying a fluid system under linear thermal stress and non-linear thermal stress decreases with an increase of thermal load,and the decrease becomes larger and larger.In the same case,the critical velocity under nonlinear thermal stress is greater than that under linear thermal stress,and the gap between them increases with an increase of thermal load.Comparing the boundary conditions,it is found that fixed boundary conditions can bear the largest thermal load.Therefore,applying fixed boundary conditions to the pipes conveying fluid system under the thermal load is beneficial to improve the stability of the system.In this paper,the analytical method for critical velocity of pipes conveying fluid under thermal load can be obtained conveniently and quickly at the engineering site,which provides a reference for the design and safety evaluation of pipes conveying fluids under thermal load.
作者
陈严飞
敖川
董绍华
刘昊
马尚
夏通璟
CHEN Yanfei;AO Chuan;DONG Shaohua;LIU Hao;MA Shang;XIA Tongjing(National Engineering Laboratory for Pipeline Safety/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology,China University of Petroleum-Beijing,Beijing 102246,China;State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology,Dalian 116024,China)
出处
《石油科学通报》
2021年第1期138-144,共7页
Petroleum Science Bulletin
基金
国家重点研发计划(2017YFC0805800)
国家自然科学基金(51779265)
大连理工大学工业装备结构分析国家重点实验室开放基金(GZ19119)
深水油气管线关键技术与装备北京市重点实验室开放基金(BIPT2018002)和中国石油大学(北京)科研基金资助(2462020YXZZ045,2462017BJB10)联合资助。
关键词
输流管道
支承管道
热荷载
临界流速
解析方法
pipes conveying fluid
supported pipes
thermal loads
critical velocity
analytical method
