鼓泡塔中气泡群运动的实验与模拟

采用高速摄像法测量了均匀鼓泡流状态下,水以及体积分数分别为20%和40%的甘油-水体系中气泡群的浮升运动,考察了气含率、雷诺数和分布器孔径对气泡尺寸、形状、浮升速率和曳力系数的影响。构建了立方体单元胞模型,并根据雷诺数的不同选取层流和湍流模型,模拟得到气泡的浮升速率和曳力系数与实验值吻合较好。结果表明:随着气含率及液体黏度的提高,气泡群浮升阻力增大,浮升速率减少;随着雷诺数和气泡直径的增加,曳力系数减小,气泡浮升速率增大。单元胞模型能较好地反映气泡群浮升过程中各因素的影响,是处理气泡群运动的有效工具。

Experiment and Numerical Simulation of the Motion of Bubble Swarm in a Bubble Column

High-speed digital video processing was used to measure the motion of bubble swarm in water, 20% glycerol-water and 40% glycerol-water mixture under the uniform bubble flow state, respectively. The effects of gas holdup, Reynolds number and distributor aperture on the bubble size and shape, bubble velocity and drag coefficient were investigated. The cubic cell model was established and the laminar flow model and turbulent flow model were selected according to the different Reynolds number to simulate the motion of the bubble swarm. The results showed that the numerical rise velocity and the drag coefficient of the bubbles were in good agreement with the experimental data. The rise resistance of the bubble swarm increased and the rise velocity decreased with the increase of gas holdup and liquid viscosity. With the increase of the Reynolds number and the bubble equivalent diameter, the bubble swarm drag coefficient decreased and the rise velocity increased. It is suggested that the cell model can well reflect the influences of various factors in the process of the bubble swarm motion and it is an effective tool to deal with the movement of the bubble swarm.