Mixed convection in horizontal channels partially filled with aluminium foam heated from below and with external heat losses on upper plate

摘要

In this work mixed convection in a horizontal channel partially filled with a porous medium and the lower wall heated at uniform heat flux is studied both experimentally and numerically. The experimental test section is made of a horizontal wall and a parallel wall with heat losses toward the external ambient. A simplified two dimensional numerical model is considered to evaluate the dynamic and thermal fields inside the heated channel. The investigation allows to evaluate the effect of the aluminium foam on the mixed convection in the heated channel by wall temperature measurements and flow visualization. Results are given for heated channel without and with foam in terms of wall temperature profiles for different Reynolds number value, from 100 to 300, wall heat flux and for aluminium foam with 10 and 20 pore per inch. Experimental and numerical results are given in terms of wall temperature profiles and both allow to show that the foam determines lower wall temperature profiles along the fluid flow than the ones in the clean channel cases. Moreover, the foams with different pores per inch present different local thermal behaviours. The simplified numerical model allows to estimate the possible heat losses toward the external ambient.