水平管内气液两相泡状流进口段的实验研究

Experiment Study on the Wall Shear Stress Developing Length in Horizontal Gas-Liquid Two-Phase Bubbly Flows

在水、空气实验回路上对水平管内气液两相泡状流的壁面切应力进口段进行了实验研究 .通过测量实验段入口段的压强梯度沿管长的变化来确定进口段的长度 .在实验中 ,分别使用了轴向进气 (A型 )和径向进气 (B型 ) 2种混合器 .通过对实验数据的综合分析 ,给出了预测进口段的关联式 .实验及计算结果表明 ,在实验参数范围内 ,控制单相水和两相泡状流壁面切应力进口段的主要机理是相同的 ;进口段长度随液流雷诺数的增大而增大 ,随截面含气率的增加而增大 ;实验值和估算值的偏差在 10 8%以内 .

Experiments were carried out to investigate the developing length due to the wall shear stress in horizontal air water two phase bubbly flows. A plexiglass tube with an internal diameter of 35mm and a length of 10 m was used as the test section, and the axial pressure gradient of air water bubbly flows in the tube was measured to determine the developing length. Two types of mixer were adopted, in which air was injected into the flows axially and radially respectively. It was observed that the shear stress developing length showed a dependence on liquid Reynolds number, void fraction and air injection method. The experiments indicate that the mechanisms goveming the wall shear stress development of single phase and two phase bubbly flow are the same. The developing length increases,with the liquid Reynolds number and the void fraction. Two developing length correlations were presented, the relative deviation is 10 8 percent.