泡沫金属的热分析.pdfVIP

第 31 卷 第 7 期 北 京 科 技 大 学 学 报 Vol . 31 No. 7 2009 年 7 月 Journal of University of Science and Technology Beij ing Jul . 2009 泡沫金属的热分析 刘晓丹 　冯妍卉 　杨雪飞 　张欣欣 北京科技大学机械工程学院 , 北京 100083 摘 　要 　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. 关键词 　泡沫金属 ; 有效热导率 ; 对流换热 ; 数值模拟 ; 孔隙率 分类号 　TB 383 ; T K 124 Thermal analysis on metal f oa ms L I U X iaodan , FEN G Yanhui , YA N G X uef ei , ZHA N G X inx in School of Mechanical Engineering , Univer sit y of Science and Technology Beijing , Beijing 100083 , China ABSTRACT 　A simplified geometrical model of high porosity op encell metal foams was constructed . A related expression of effective t hermal conductivity of t he metal foams was derived on t he base of t he analogy between t hermal and electrical resistance at t he scale of unit pore . The correlation was furt her modified by existing exp erimental data . In addition , convective heat transfer was numerically simulated for air flow in a metalfoam filled t hreedimensional rectangular duct . The simulation result s were analyzed and comp ared wit h exp erimental data . It is shown t hat t he calibrated effective t hermal conductivity model is applicable for aluminium metal foams. Under t he condition of t he same porosity , t he convective heat transfer of forced flow in t he duct is enhanced by using higher porosity (i . e . smaller pore size) metal foams , but at t he exp ense of a higher pressure drop . To some extent , metal foams wit h a lower pore density have a better overall p erforman