平口管口处气泡行为特征数值模拟

为研究平口管口处单个气泡行为特征,采用流体体积模型(Volume of Fluid, VOF)方法,数值模拟研究气泡的膨胀脱离过程,对比分析了浸没方式、管径、气体速度、液体密度和表面张力对气泡膨胀脱离时间和脱离直径的影响规律。研究结果表明:在3种不同管口浸没方式下,气泡膨胀脱离时间均随管口气体速度增大而降低,但降低速率逐渐减小;在底部和顶部浸没方式下,气泡膨胀脱离时间和脱离直径随表面张力增大而增加,随液体密度增大而降低;对于侧面浸没方式,气泡膨胀脱离时间和脱离直径随表面张力增大整体呈上升趋势,而受液体密度影响不大。气泡膨胀脱离时间与气泡脱离直径呈正相关。所建立的数学模型能够真实地模拟气泡形成及运动特征,从而提供一个有效的研究方法。

Numerical Simulation on Bubble Behavior at Nozzle of Vertical Flat Pipe

VOF (Volume of Fluid) model is employed to study the behavior of single bubble at nozzle of vertical flat pipe. The process of bubble expansion and detachment is simulated, and the influences of immersion mode, nozzle diameter, gas velocity, liquid density, and surface tension on bubble expansion detachment time and detachment diameter are comparatively analyzed. Results demonstrate that the bubble expansion and detachment time shortens with the increase of gas velocity at the nozzle, and then tends to be gentle gradually under three different nozzle immersion modes. In the bottom-immersion and top-immersion mode, the bubble expansion detachment time and detachment diameter both increase with the growth of surface tension, while decline with the climbing of liquid density. In the side-immersion mode, the bubble expansion detachment time and detachment diameter both increase with the growth of surface tension, whereas the effect of liquid density is subtle. There is a positive correlation between the bubble expansion and detachment time and the bubble detachment diameter. The established mathematical model offers an effective research approach by simulating the formation and motion of bubbles truly.