The influence of nozzle-to-plate spacing on heat transfer and fluid flow of submerged jet impingement

In this study, heat transfer and fluid flow characteristics of a submerged jet impinging on a flat plate surface are experimentally investigated. The working fluids are air and water. The effects of a wide range of nozzle-to-plate spacing (H/d = 0.1 − 40) on the Nusselt number and pressure at stagnation point are considered. The results show that the Nusselt number and pressure are divided into three regions; region (I) jet deflection region (H/d ⩽ 0.6), region (II) potential core region (0.6 < H/d ⩽ 7), and region (III) free jet region (7 < H/d ⩽ 40). In region I, the Nusselt number and pressure drastically increase with decreasing the nozzle-to-plate spacing. In region II, the effect of the nozzle-to-plate spacing is negligible on the Nusselt number and pressure. In region III, the Nusselt number and pressure monotonically decrease with increasing the nozzle-to-plate spacing. Based on the experimental results, new correlations for the normalized stagnation Nusselt number and pressure are developed as a function of the nozzle-to-plate spacing alone.