HEAT-TRANSFER AND FLUID-FLOW OF TURBULENT NATURAL-CONVECTION ALONG A VERTICAL FLAT-PLATE WITH A BACKWARD-FACING STEP

Heat transfer and fluid flow of turbulent natural convection along a vertical flat plate with a backward facing step were investigated experimentally. The effect of step height on heat transfer was classified through a series of heat transfer measurements. The wall temperature and fluid flow were then visualized using a liquid-crystal sheet and water-soluble fluorescent paint in order to investigate the separation and reattachment of fluid flow. It was revealed that the characteristic low-temperature patterns appear on the backward heat transfer plate and that they play a significant rob in heat transfer enhancement. These patterns are generated by the penetration of the low-temperature fluid lumps having three-dimensional and unstable structures near the wall. It was further found that the maximum heat transfer point is not consistent with the reattachment point of the separated flow and that these points shift downstream with increasing step height.