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有效导热系数是泡沫金属工程应用中传热相关设计的一个重要参数。该文基于简化元胞结构模型,通过直接求解样品内部导热微分方程和辐射传递方程,研究FeCrAlY开孔泡沫金属的有效导热系数。比较了基于剖球模型与传统等截面支架搭接模型的计算结果,分析剖球模型下孔隙单元尺寸、孔隙率、样品平均温度等因素对有效导热系数的影响。研究结果表明,孔隙单元结构对有效导热系数的影响很大,不能仅通过孔隙率和孔隙数密度来研究有效导热系数的变化规律。高温下辐射传热占主导,孔隙率越高,孔隙越大,有效导热系数对温度越敏感。增大孔隙率、减小孔隙尺寸、降低工作温度等会减小泡沫金属的有效导热系数。基于简化几何模型的直接数值模拟可以作获得泡沫金属有效导热系数的一种行之有效的方法。
Effective thermal conductivity is an important parameter for heat transfer related design in foam metal engineering applications. Based on the simplified cellular structure model, the effective thermal conductivity of FeCrAlY open-cell metal foam was studied by solving the differential equations of internal heat transfer and the radiation transfer equation directly. The calculation results based on the lapped model of the cross-section scaffolding and the traditional cross-section scaffold are compared. The influence of pore size, porosity and sample average temperature on the effective thermal conductivity is analyzed. The results show that the pore structure of the cell has a great influence on the effective thermal conductivity, and the change rule of the effective thermal conductivity can not be studied only by the porosity and the number density of the pores. Radiation heat transfer dominated at high temperatures, the higher the porosity, the larger the porosity, the more effective the thermal conductivity of the more sensitive to temperature. Increasing the porosity, reducing the pore size, reducing the working temperature, etc. will reduce the effective thermal conductivity of the foam metal. Direct numerical simulation based on simplified geometric model can be an effective method to obtain the effective thermal conductivity of foam metal.