泡沫金属的热分析

Thermal analysis on metal foams

提出了一种高孔隙率开孔泡沫金属的结构简化几何模型,运用热电比拟理论在胞孔尺度上分析并求解了有效热导率的计算表达式,并根据已有实验数据进行模型修正.同时模拟分析了金属泡沫三维矩形通道内空气流动的对流换热情况,与实验结果进行了对比验证.研究表明,本文提出的胞孔有效热导率修正模型对铝泡沫金属有一定的适用性;相同孔隙率条件下,泡沫金属通道内强制对流的对流换热系数随孔密度的增加(即孔径的减小)而增大,但付出的代价是阻力也随之增大;相对而言,低孔密度的泡沫金属具有较好的对流换热综合性能.

A simplified geometrical model of high porosity open-cell metal foams was constructed. A related expression of effective thermal conductivity of the metal foams was derived on the base of the analogy between thermal and electrical resistance at the scale of unit pore. The corre.lation was further modified by existing experimental data. In addition, convective heat transfer was numerically simulated for air flow in a metal-foam filled three-dimensional rectangular duct. The simulation results were analyzed and compared with experimental data. It is shown that the calibrated effective thermal conductivity model is applicable for aluminium metal foams. t Under the condition of the same porosity, the convective heat transfer of forced flow in the duct is enhanced by using higher porosity （i. e. smaller pore size） metal foams, but at the expense of a higher pressure drop. To some extent, metal foams with a lower pore density have a better overall performance on convective heat transfer.