Numerical simulation of gas-liquid two-phase flow and convective heat transfer in a micro tube
Numerical simulation of gas-liquid two-phase flow and convective heat transfer in a micro tube
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DOI：
10.1016/j.ijheatfluidflow.2006.04.010
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发表时间：
2007-02-01
影响因子：
2.6
通讯作者：
Himeno, Takehiro
中科院分区：
文献类型：
--
作者：
Fukagata, Koji;Kasagi, Nobuhide;Himeno, Takehiro
对20 μ m内径管内空气和水两相流动进行了数值模拟。重点研究了气泡列流的流动和传热特性。假设一个轴对称的二维流动。采用有限差分法求解控制方程，采用水平集法捕获气液界面。在每次模拟中，平均压力梯度和壁面热流密度保持不变。在不同压力梯度和孔隙率条件下进行了重复模拟。气相和液相的表面雷诺数分别为0.34-13和16-490，毛细管数为0.0087-0.27。无论流动条件如何，气相速度大约是液相速度的1.2倍。这与大尺寸管中两相流的Armand相关是一致的。发现两相摩擦系数与基于爱因斯坦型有效粘度的雷诺数成比例。计算得到的壁面温度分布与实验中观察到的小通道的壁面温度分布在质量上是相似的。气泡下的局部努塞尔数明显高于单相流。(c) 2006爱思唯尔公司版权所有。
Numerical simulation of an air and water two-phase flow in a 20 mu m ID tube is carried out. A focus is laid upon the flow and heat transfer characteristics in bubble-train flows. An axisymmetric two-dimensional flow is assumed. The finite difference method is used to solve the governing equations, while the level set method is adopted for capturing the interface of gas and liquid. In each simulation, the mean pressure gradient and the wall heat flux are kept constant. The simulation is repeated under different conditions of pressure gradient and void fraction. The superficial Reynolds numbers of gas and liquid phases studied are 0.34-13 and 16-490, respectively, and the capillary number is 0.0087-0.27. Regardless of the flow conditions, the gas-phase velocity is found approximately 1.2 times higher than the liquid-phase velocity. This is in accordance with the Armand correlation valid for two-phase flows in macro-sized tubes. The two-phase friction coefficient is found to be scaled with the Reynolds number based on the effective viscosity of the Einstein type. The computed wall temperature distribution is qualitatively similar to that observed experimentally in a mini channel. The local Nusselt number beneath the bubble is found notably higher than that of single-phase flow. (c) 2006 Elsevier Inc. All rights reserved.