气体滑脱现象的综合特征参数研究

INTEGRATED CHARACTERISTIC PARAMETER STUDY OF THE GAS SLIPPAGE PHENOMENON

当气体在致密孔隙介质中低速渗流时 ,表现出有别于油、水等液体渗流的重要物理现象—滑脱现象 ,文章认为气体分子与孔隙壁的碰撞作用是滑脱现象发生的物理机理 ,它由孔隙介质的结构和气体分子随自由程的分布共同决定。滑脱现象将在低压力段引起气体渗流规律对达西线性关系的偏离 ,孔隙愈致密 ,气体压力愈低 ,该现象引起的偏离愈明显。通过对气体在孔隙介质中低速渗流时发生的基本作用分析和应用量纲理论 ,确定描述滑脱现象的综合特征参数是d/λ。实验测得当d/λ≤ 4 .5时 ,对于低速渗流的气体 ,这是既存在粘滞流动 ,同时滑脱流动又不可忽略的情况 ,在其渗流规律中应考虑由于滑脱现象的存在所带来的影响。文章分别由理论计算和对实验结果的分析拟合得到了关于d/λ的函数 ,二者基本吻合。该函数能正确描述这种情况下气体的渗流规律。

The important physical phenomenon,gas shows difference from oil and water when gas flows at low velocity in tight porous media,is gas slippage phenomenon.The article points out that the collision function between gas molecules and pore walls is the mechanism caused the phenomenon.Gas slippage phenomenon depends on configuration of porous media and the average free-path of gas molecules, and causes deviating off Darcy's law in low pressure.The tighter porous media is,the lower pressure of gas is,and the more obvious gas slippage phenomenon.With analyzing the basic functions of the phenomenon and applying dimension theory,it's determined the integrated characteristic parameter to describe slippage phenomenon is.According to experiment results,when is smaller than 4.5, viscous flow happens with slippage flow simultaneously.In this case,the influence of gas slippage phenomenon on the regulations of gas flow must be considered.The function describes the law of gas flow in the case.The function is obtained by theory calculation and analysis of experimental results separately,and both of them are consistent in the whole.