关键词: 逆流气液两相流, 规整填料, 分离涡模拟, 流体动力学特性, F因子

Abstract: In order to study the influence of gas flow rate on flow structure,interface motion of counter-current gas-liquid flow over structured packing surface,a CFD model based on detached eddy simulation(DES)and volume of fluid(VOF)method was developed.Explicit interpolation scheme was used for the VOF formulations,and the Geo-Reconstruct method was chosen as the volume fraction discretization scheme.Structured curvilinear grids were generated for the whole fluid domain and locally refined to ensure that at least 10 grid points were within the liquid film.When F factor was low(F≤1.354 Pa^0.5),the distribution of free-surface and its velocity component v_y were periodic,and the fluctuation amplitude was almost uniform.Along the free-surface all values of v_y were negative.As F=3.386 Pa^0.5,fluctuation of free-surface appeared to be disturbed,while the distribution of v_y kept periodic,and at the lower edge of liquid waves v_y>0.As F=5.418 Pa^0.5,back mixing of liquid phase appeared,recirculation regions were formed in both phases and evolved with the liquid back mixing process,and the liquid film could wholly move upward in some concaves of solid surface.As F≥6.772 Pa^0.5,dry patch was formed at the lower part of packing region and no liquid could flow out from the bottom outlet.With the increment of F factor,both liquid holdup and effective interfacial area increased first and then decreased.

Key words: counter-current gas-liquid two-phase flow, structured packing, detached eddy simulation, hydrodynamics, F factor