Abstract:

The additional inertial forces caused by rolling conditions would affect the two-phase flow pressure drop and the forces acting on the bubbles.Numerical simulation of subcooled flow boiling in a vertical rectangular channel under the effect of additional inertial forces has been carried out considering the energy and mass transfer during phase change.The two-phase flow model of volume-of-fluid (VOF) was adopted.The liquid-vapor interface was captured using the piecewise linearity interpolation calculation (PLIC) geometry restructuring method.The pressure, velocity, temperature distribution around an isolated bubble, the secondary flow phenomenon caused by evaporation and condensation, and the evolution of velocity vector during bubble coalescence were obtained, which agree well with the results in literature.Compared with motion less conditions, the pressure drop was enlarged by the effect of additional inertial forces.In subcooled flow boiling, the pressure drop fluctuates because of the vapor generation.The fluctuation becomes more severe while heat flux increases.Compared with the effects of other forces acting on bubbles, the effect of additional inertial forces can be neglected.However, the fluctuation of flow rate caused by rolling would change the shear lift force, drag force and hydrodynamic pressure force significantly and influence the heat transfer in boiling flow.

Key words: FONT-SIZE: 10.5pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体" lang=EN-US>FONT-SIZE: 10.5pt, mso-ascii-font-family: Times New Roman, mso-bidi-font-family: Times New Roman, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-hansi-font-family: Times New Roman">数值模拟；附加惯性力；过冷流动沸腾；汽泡动力学；FONT-SIZE: 10.5pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体" lang=EN-US>VOF

摘要：

摇摆条件下附加惯性力的作用会对两相流动的压降及汽泡受力产生影响。考虑相变能量和质量输运，采用流体体积(VOF)多相流模型对附加惯性力条件下竖直矩形流道内过冷流动沸腾进行了数值模拟。汽液界面位置通过分段线性插值(PLIC)的方法获得。模拟结果获得了孤立汽泡周围压力、速度、温度分布以及二次流动现象，分析了汽泡聚合过程汽泡形态及内部速度矢量的演变过程，模拟结果与文献中结论吻合良好。附加惯性力作用使得流动压降比静止条件下要大，过冷流动沸腾压降由于汽相产生会在单相流动的基础上产生波动，且热通量越大，压降波动幅度越大。摇摆产生的附加惯性力相对汽泡所受的其他力而言可以忽略不计，而摇摆导致的流量波动会改变汽泡受力大小，进而影响沸腾换热。

关键词: FONT-SIZE: 10.5pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体" lang=EN-US>FONT-SIZE: 10.5pt, mso-ascii-font-family: Times New Roman, mso-bidi-font-family: Times New Roman, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-hansi-font-family: Times New Roman">数值模拟；附加惯性力；过冷流动沸腾；汽泡动力学；FONT-SIZE: 10.5pt, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, mso-bidi-language: AR-SA, mso-fareast-font-family: 宋体" lang=EN-US>VOF