基于二维Voronoi模型的多孔泡沫金属导热性能模拟研究

Simulated Analysis of Thermal Conductivity of Porous Metal Foams with 2-D Voronoi Model

多孔金属材料作为新型功能材料具有密度低、强度高、导热性能优良等特性,应用前景广阔,受到越来越多的关注。多孔材料的有效导热系数与随机孔隙结构相关,仅用孔隙率不足以描述真实材料的孔隙结构。采用二维Voronoi模型,定义孔隙随机度S和孔隙率ε作为孔隙结构参数,通过调节核点位置偏移因子α和边宽系数β改变模型的随机度S和孔隙率ε,分析随机度S和孔隙率ε对相对有效导热系数k*的影响。结果表明,随机度和孔隙率同时影响多孔泡沫材料的有效导热系数,当随机度S一定时,随着孔隙率ε增大,材料的有效导热系数k*减小;当孔隙率ε一定时,随着随机度S的增大,有效导热系数k*减小。根据大样本的有限元数值模拟结果,拟合了有效导热系数由孔隙率和随机度组成的函数表达式。

Porous metal foams is a new kind of functional material with low density,high mechanical strength,high thermal conductivity and other excellent properties.Porous metal foam has a wide application prospect and has been widely concerned and studied.The effective thermal conductivity（k＊）of porous material is related to the pore structure.Only the porosity（ε）is not enough to describe the pore structure of the real material.Based on 2-D Voronoi model in this paper,the randomness（S）and porosity of models were defined to describe the pore structure parameters.By adjusting the deviation factor（α）and edge width coefficient（β）of the model to change the range of randomness and porosity.The influence of the randomness and porosity on the effective thermal conductivity of the model was analyzed,which showed that the randomness and porosity affect the effective thermal conductivity.Results showed that randomness increasing leads to effective thermal conductivity decreasing.From the simulations results of random models,it is pointed that the relative effective thermal conductivity of porous metal foam material can be expressed as power function of porosity and randomness.