Flow visualization of fluid flow through a U-bend channel with periodical high-permeability porous blocks

The issue about the heat transfer enhancement in a 180-deg turned channel has attracted many attentions. The heat transfer capacity is influenced strongly by the behavior of the fluid flow. This work experimentally investigated the fluid flow characteristics in a 180-deg round turned channel with discrete aluminum-foam blocks. The air was used as coolant. Several aluminum-foam blocks (0.90 porosity and 10 PPI pore density) were installed discretely in the 180-deg round turned channel with the square cross section. Four kinds of test section were employed to perform the flow visualizations. The results indicate that the arrangement of aluminum-foam blocks impacts on the flow pattern remarkably. The present results can be used to explain the pressure drop characteristics of such aluminum-foam channel, and be benchmarking by other investigators who would like to solve this problem numerically.