泡沫材料流场内两相流动的数值模拟

Numerical Simulation of Two-phase Flow in Foam Material Flow Field

本文建立了PEMFC泡沫材料流场的三维数值模型。对泡沫材料的几何结构进行重构,选取正12面体作为胞体结构,保证孔隙均匀分布及骨架结构完整。研究了不同几何参数、边界条件对泡沫流场内单相、气-液两相流动的影响。研究发现,相比于传统流道,泡沫流场进气效率提升,增强了垂直极板方向的对流。随着孔隙率、进气流速的增加及孔尺寸的减小,流道进出口压差增大。多孔结构的存在会降低排水速度,但其提供的气体通路将保证气体的运输及流通。

A three-dimensional(3-D)model of foam material flow field(FMFF)of PEM fuel cells is developed in this paper.The model uses dodecahedra as representative geometry unit to reconstruct the morphology of foam material and the unit is arrayed along special directions for the homogeneity and completeness of ligament structure.The effects of particular geometry parameters and boundary conditions on the single-phase and two-phase flow in FMFF are discussed.It is found that the reactant supply efficiency of FMFF is higher because the vertical convection is largely enhanced compared with conventional flow channels.In addition,the pressure difference between inlet and outlet will increase with the increment of porosity,inlet velocity and the reduction of pore diameter.Besides,the porous structure will slow down the water expelling process but meanwhile it can provide flexible gas pathways for the gas reactant transport.