不同曲率支管弯管对T型管湍流混合下热疲劳的影响

为了探究不同曲率支管弯管对T型管冷热流体混合下热疲劳的影响，分别对支管上游曲率为0.006、0.01、0.02这3种弯管结构的T型管内冷热流体的混合过程进行大涡模拟（LES），将计算得到的瞬时温度和压力载荷动态地加载到固体域进行流固耦合计算，得到管道的热应力分布情况；再利用雨流计数方法对获得的波动热应力进行统计学分析，根据线性疲劳损伤累计准则进行热疲劳评估，得到管道的无量纲累计疲劳损伤率。将各个结构的无量纲时均温度、无量纲均方根温度和无量纲热疲劳损伤率等进行对比，数值结果表明：3种结构的温度和应力的分布和波动相似；随着曲率的增大，温度波动变得剧烈，而相贯区热应力集中逐渐减弱，同时其无量纲累计疲劳损伤率呈降低趋势。

Influence of the elbow of branch pipes with different curvature on thermal fatigue under turbulent mixing in a T-junction

Large eddy simulation (LES) of the mixing process of cold and hot fluids have been carried out in order to study the thermal fatigue in T-junctions with branch elbows having different upstream curvatures of 0.006, 0.01 and 0.02. First, we loaded the obtained instantaneous temperature and pressure dynamically into the solid domain to calculate the fluid dynamics-finite element modeler coupling, which affords the thermal stress distribution of the pipeline. Then, a rainflow-counting algorithm was used to analyze the resulting fluctuating thermal stress statistically. According to the linear cumulative fatigue damage rule, we evaluated the thermal fatigue and calculated the dimensionless cumulative fatigue damage rate of the pipeline. We then compared the normalized mean temperature, the normalized root mean square temperature and normalized thermal fatigue damage rate for each structure. The numerical results showed that the fluctuations in temperature and stress distributions are similar for all three structures. However, as the curvature increases, the temperature fluctuates more dramatically, while the thermal stress concentration in the intersecting zone decreases gradually, and the dimensionless cumulative fatigue damage rate shows a decreasing trend.