Abstract:

Studies on flow characteristics in open-cell metal foams have until now been limited to the analysis of local flow characteristics, while gas-liquid two-phase flow in large-scale (over 100cm²) metal foams requires more research. In order to deepen our understanding of the latter phenomenon, the optical flow visualization of gas-liquid and liquid-gas displacement in metal foam sheets has been carried out. Analysis was undertaken on the effects of the velocity of invading fluid and pore sizes of metal foam on two-phase flow. Results showed that for gas-liquid displacement, an increase in air velocity causes a change in the interface morphology of the gas-liquid phase from capillary to viscous fingering, while a decrease in foam pore size causes an increase in the partial drainage phenomenon. For liquid-gas displacement, it was observed that the gas-liquid interface is relatively regular and roughly tapered. An increase in displacement velocity increases the taper angle, reduces interface length. Partial drainage was noticeably observed only in metal foam with the smallest pore diameter and becomes more pronounced with a decrease in water velocity.

Key words: metal foam, porous media, gas-liquid flow, two-phase displacement

摘要：

开孔金属泡沫内流动特性的研究多局限于局部流动特性的分析，大尺寸（100cm²以上）金属泡沫内气液两相宏观流动特性的研究目前较为缺乏。为了深入认识金属泡沫内气液两相流动特性，本文通过光学可视化手段，对金属泡沫多孔介质薄层内的气/液驱替、液/气驱替两相流动过程进行研究，分析了入侵流体的流速及金属泡沫的孔径对泡沫薄层内两相流动的影响。结果表明：在气/液驱替流动方面，随着空气流速的增大，气液两相的界面形态由毛细指状结构过渡到黏性指状结构，随着泡沫孔径的减小，部分排水现象愈加显著；在液/气驱替流动方面，气液界面较为规则，近似呈锥形，且流速越大，界面锥角越大、长度越小，试验中仅在最小孔径的金属泡沫中捕捉到明显的部分驱替现象，并且随着水流速的减小愈加显著。

关键词: 金属泡沫, 多孔介质, 气液两相流, 两相驱替