T型管湍流穿透现象的热流固耦合疲劳分析

在石油、化工、核电等管道系统中存在大量T型管道,由于其主支管流体的流量及温度存在差异导致产生湍流穿透现象,引发T型交汇处温度与速度场波动,进而可能诱发管道热疲劳问题。首先使用大涡模拟（LES）方法计算湍流穿透工况下管道内流场各物理量的时空演变规律,结果表明在支管轴向无量纲高度H=4截面处温度波动最为强烈;然后建立瞬态热流固耦合计算过程,将面压力与体温度动态加载到固体域,得到管道应力分布情况,找出危险点所在位置为轴向H=0截面内壁面;最后使用雨流计数法对危险点应力波动信息进行统计学分析,依据Goodman曲线得到等效对称循环载荷,根据线性疲劳损伤累积准则对危险点疲劳寿命进行评估,最终得到管道的疲劳寿命。

CFD-FEM simulation and fatigue analysis of a T-junction under turbulent penetration

There are a large number of T-junctions in petroleum, chemical and nuclear power pipeline systems. The turbulent penetration phenomena caused by the difference in the flow and temperature between the main and branch pipe of the T-junctions give rise to temperature and velocity fluctuations. These may cause thermal fatigue problems. In this work the large-eddy simulation (LES) method was used to calculate the temporal and spatial evolution of temperature and velocity in the flow field. The results show that the fluctuation is strongest at the dimensionless axial height of the H=4 surface. A transient thermo-fluid-solid coupling simulation process was then established, and the surface pressure and body temperature were dynamically loaded into the solid domain to obtain the stress distribution of the pipeline and find the location of the danger point. This was found to be the axial height H=0 of the inner wall surface. Finally, the rainflow cycle counting algorithm was used to analyze the stress fluctuation information for the danger point, the equivalent symmetrical cyclic stress was obtained according to the Goodman curve, and the fatigue life of the danger point was evaluated according to the linear fatigue damage accumulation criterion. This allows the fatigue life of the pipeline to be determined.