逆向气流对薄膜流动特性影响研究

Influence of counter-current airflow on the film flow characteristics

气液二相逆流的降膜流动形式是规整填料塔内常见的流动形式,与气液并流模式相比,采用气液逆流的进料方式更有利于物质的交换。文中将在传热传质中起决定性作用的平板和波纹板上薄膜流体微观流动作为研究对象,对逆流气体存在下的薄膜流动特性进行数值仿真。采用开源CFD软件OpenFOAM进行建模,利用基于VOF法的inter Foam求解器,重点分析了不同逆流气速下,薄膜流体自由界面形状、自由界面速度、厚度方向上速度分布和流线图的变化。研究了倾斜平板和波纹板上薄膜流体受逆向气速的影响,分析发现相比平板上的两相流动,波纹板上的液膜受逆向气流的影响更复杂和剧烈,波动性更强,有助于传热传质的进行。

Counter-current gas-liquid falling film flow exists widely in the structured packing column, which is more efficient for the exchange of substances when compared with the co-current gas-liquid flow. The micro gas-liquid film flow which played an important role in the heat and mass transfer on the plate and sinusoidal corrugated plate was focused as study object, the numerical simulation was calculated, and the influence of counter-current airflow on the flow characteristics of the liquid film was studied. Numerical simulation was conducted by the multiphase flow solver interFoam based on VOF （volume of fluid） method in the open-source computational fluid dynamics software OpenFOAM. The shape of the free surface, the velocity distributions on free surface and along the thickness of the film, as well as the streamlines were analyzed. Based on that, the flow characteristics on the inclined plate and sinusoidal corrugated plate affected by the counter-current airflow were obtained. By comparing with gas-liquid flow on the plate, volatility of liquid flow on the sinusoidal corrugated plate was severer and stronger under the influence of counter-current airflow, which can be better for heat and mass transfer.