不同动量比对T型管冷热流体掺混及管道热疲劳的影响

Influence of different momentum ratios on the mixing of hot and cold fluids and thermal fatigue of a T-junction

为探究主支管流体不同动量比对T型管道内冷热流体掺混过程及管道热疲劳程度的影响,通过对T型管内不同主支管流体动量比工况下冷热流体的掺混过程进行大涡模拟(LES),计算得到管道壁面及管道内流体的温度波动情况,并使用同一套T型管网格模型进行了流固耦合计算,得到了动量比对T型管道热应力及热疲劳寿命的影响规律。计算结果表明,当动量比变化使得T型管内流体的搅混流型发生变化时,动量比对管道热疲劳的影响明显,其中,搅混流型为偏转流时,管道的热疲劳现象相较于搅混流型为壁面流的热疲劳现象得到明显的改善,预测热疲劳寿命从8.81×10^(-4)年提高到5.40×10^(15)年。因此,随着主支管流体动量比的降低,流体搅混流型从壁面流转变为偏转流,管道的热疲劳寿命得到明显提高。

In order to explore the influence of different momentum ratios of the main and branch fluid on the mixing process of cold and hot fluid and the thermal fatigue of a T-junction,large eddy simulations(LES)have been used to simulate the mixing process of hot and cold fluids in a T-junction for different momentum ratios of the main and branch pipes.The temperature fluctuation of the fluid and pipe wall was calculated,the fluid solid interaction(FSI)calculation was then carried out with the same Tjunction grid model,and the influence of the momentum ratio on the thermal stress and thermal fatigue life of the Tjunction was thus obtained.The results show that when the momentum ratio changes cause the fluid jet flow in the Tjunction to change,it has a significant effect on the thermal fatigue of the pipe.When the jet flow is the deflected flow,the thermal fatigue phenomenon of the pipe is obviously improved compared with when the jet flow is the wall flow,and the predicted thermal fatigue life increases from 8.81×10^(-4) years to 5.40×10^(15) years.Therefore,the momentum ratio of the main and branch pipes decreases,the jet flow of the fluid gradually changes from wall flow to deflection flow,and the thermal fatigue life of pipes can be significantly improved.