金属丝网毛细特性的孔隙尺度数值分析

Metallic woven meshes have received considerable attention in several engineering applications as filtration, catalysis, heat transfer enhancement and explosion suppression owing to their merits of controllable pore structure, high specific surface area, high mechanical strength and low price. In order to characterize their capillary performance, firstly, the detailed geometrical dimensions of four kinds of square-shaped plain weave wire screen with different mesh numbers were measured. Then a numerical model was developed to evaluate the fluid dynamics of a porous woven mesh at the pore scale. Finally, based on the pore scale numerical results, the effects of wire diameter and mesh number on porosity, specific surface area and permeability were analyzed. The study found that the Kozeny-Carman formula can better predict the permeability relationship of wire mesh at low flow rates (less than 0.01 m/s), and the geometric factor has a logarithmic relationship with the mesh diameter. While at high flow rates (larger than 0.01 m/s), the flow regime transition from Darcy to Forchheimer, the inertial contribution can not be neglected. The Darcy and non-Darcy permeability coefficient can be obtained by Forchheimer correlation, and the relationship between permeability and porosity and wire diameter is modified according to Kozeny-like model. The obtained fitting formulae between geometric structure and capillary performance of plain woven wire mesh provide a design guideline for the metallic woven mesh used for wicking and transpiration cooling.