ABSTRACT

The effect of the metal foam thickness on the conduction and convection heat transfer for a metal foam flat plate impinged by a circular air jet is investigated. The IR thermography and thin-metal foil technique are used for the measurement of local heat transfer. An open-cell aluminum metal foam is used for the metal foam flat plate. A 3D-printed resin foam and detached metal foam flat plate are used for the appreciation of the conduction and convection heat transfer. The varying parameters are the thickness of the foam, Reynolds number, and the nozzle exit to plate distance. The presence of the metal foam offers a conduction effect. This predominates over the attenuation in the convective heat transfer by foam due to additional hydraulic resistance. The additional hydraulic resistance offered by the porous foam increases with the increase in the foam thickness. The heat transfer of a porous foamed flat plate decreases with the increase in the foam thickness. The local Nusselt number of the resin foam and detached foam flat plate is almost the same. The conduction effect and attenuation in the convection heat transfer of a metal foam flat plate are quantified by attenuation and enhancement factors. The overall augmentation offered by 4, 8, and 12 mm thick metal foam flat plates is 1.71, 1.42, and 1.43 times compared to the smooth flat plate case, respectively. Hence, it is advisable to use a metal foam flat plate with 4-mm-thick metal foam under circular air jet impingement.

摘要

研究了泡沫金属厚度对圆形空气射流冲击的泡沫金属平板的传导和对流传热的影响。红外热成像和薄金属箔技术用于测量局部传热。泡沫金属平板采用开孔泡沫铝金属。使用3D打印的树脂泡沫和分离的金属泡沫平板来欣赏传导和对流传热。变化的参数是泡沫的厚度、雷诺数和喷嘴出口到板的距离。金属泡沫的存在提供了传导效应。由于额外的水力阻力，这在泡沫对流热传递的衰减中占主导地位。多孔泡沫提供的附加液压阻力随着泡沫厚度的增加而增加。多孔泡沫平板的传热随着泡沫厚度的增加而降低。树脂泡沫和分离泡沫平板的局部努塞尔数几乎相同。泡沫金属平板对流换热中的传导效应和衰减通过衰减和增强因子来量化。与光滑平板外壳相比，4、8和12毫米厚的金属泡沫平板的整体增强能力分别是1.71、1.42和1.43倍。因此，在圆形空气射流冲击下，建议使用厚度为4mm的泡沫金属平板。树脂泡沫和分离泡沫平板的局部努塞尔数几乎相同。泡沫金属平板对流换热中的传导效应和衰减通过衰减和增强因子来量化。与光滑平板外壳相比，4、8和12毫米厚的金属泡沫平板的整体增强能力分别是1.71、1.42和1.43倍。因此，在圆形空气射流冲击下，建议使用厚度为4mm的泡沫金属平板。树脂泡沫和分离泡沫平板的局部努塞尔数几乎相同。泡沫金属平板对流换热中的传导效应和衰减通过衰减和增强因子来量化。与光滑平板外壳相比，4、8和12毫米厚的金属泡沫平板的整体增强能力分别是1.71、1.42和1.43倍。因此，在圆形空气射流冲击下，建议使用厚度为4mm的泡沫金属平板。分别是光滑平板外壳的1.43倍和1.43倍。因此，在圆形空气射流冲击下，建议使用厚度为4mm的泡沫金属平板。分别是光滑平板外壳的1.43倍和1.43倍。因此，在圆形空气射流冲击下，建议使用厚度为4mm的泡沫金属平板。