多孔介质中气泡的生成机理及流动特性研究

Generation Mechanisms and Flow Characteristics of Steady Foams in Porous Medi

根据组成多孔介质的颗粒直径、颗粒排列方式、孔喉比、束缚水饱和度,将多孔介质简化为一簇变截面毛管组成的毛管束。利用质量守恒原理和动量定理,推导出单个孔隙单元内液相压力梯度和壁面剪切应力的计算公式,得到泡沫稳定流动状态时多孔介质中的压力分布以及泡沫当量直径的计算方法。通过对喉道处气泡的受力分析,推导了截断再生气泡的当量直径计算公式。利用长U型填砂管对多孔介质中稳定泡沫的流动特性进行了实验研究。研究结果表明:稳定泡沫流动时多孔介质中的压力分布呈线性下降,孔喉结构和泡沫干度是影响泡沫封堵能力的主要因素。

Porous media is simplified as a bunch of constricted capillary tubes according to the grain diameter,particle arrangement,pore-throat scaling ratio and saturation of immobile water.Following the mass conservation law and momentum principle,the pressure gradient and shear stress of fluid phase are calculated in a single pore unit.The equations of pressure distribution and equivalent diameter of bubble are established in porous media.The equivalent diameter of breaking and reforming bubble at throat is derived according to mechanical balance of flowing bubbles in constricted capillary tubes.The experiments for flow behavior of foams in U-form sandpack are carried out.The results show that the pressure distribution of steady foams linearly decreases in porous media.The pore-throat structure and foam quality are the main factors affecting the blocking ability of foams in porous media.