不同结构三通内冷热水混流特性的数值仿真

针对三通管中冷热水混流形成的热波动现象容易诱发管道的热疲劳，进而导致部件失效的问题，研究不同结构对三通管冷热水混流特性的影响.利用大涡模拟（Large Eddy Simulation，LES）方法对不同管径比和不同支管角度模型进行数值仿真.结果表明：支管入流在主管流动压迫下发生折转，从而在支管背流面上部形成涡旋，造成上壁面热波动较下壁面明显；当管径比增大时，在涡旋下通道主管流体流动有效面积减小，冷热流体混流后的热波动程度减弱，需要的掺混区域变长；当支管角度减小时，涡旋逐渐减小，冷热流体混流后的热波动程度减弱，需要的掺混区域同样变长.

Numerical simulation on characteristics of hot and cold fluids mixed in tee junctions of different structures

As to the issue that the thermal fatigue of pipe could be induced by the thermal fluctuation caused by hot and cold fluids mixed in tee junctions, the effect of different structures on the characteristics of hot and cold fluids mixed in tee junctions is studied. The Large Eddy Simulation (LES) method is used to numerically simulate the tee junction models of different diameter ratios and different angles of branch pipe. The results show that, a vortex in the downstream of branch flow is formed because the branch flow is changed by the oppression of main flow, which leads to the thermal fluctuation of upper pipe wall is more significant than that of bottom pipe wall; when the diameter ratio increases, the effective area of main pipe flow under the vortex gets smaller, the thermal fluctuation of mixed hot and cold fluids weakens, and the distance of the mixed area increases; when the angle of branch pipe decreases, the vortex disappears gradually, the thermal fluctuation of mixed hot and cold fluids weakens, and the distance of mixing area increases as well.