Double circular air jet impingement cooling of a heated circular cylinder

Experimental and numerical investigations were carried out on double circular air jet impingement cooling of a heated circular cylinder to understand flow and heat transfer characteristics. The surface of the heated cylinder was maintained at a constant heat flux condition. In the parametric study, the Reynolds number, Red defined based on the diameter of the nozzle was varied from 10,000 to 25,000. The ratio of the diameter of the nozzle to the diameter of the heated cylinder, d/D was maintained at 0.208. The effect of non-dimensional distance between double the jets (s/d) and the ratio of the non-dimensional distance between the nozzle exit and the circular cylinder surface (h/d) were investigated for the range of 4-20 and 4-16, respectively. No appreciable change was observed in the stagnation point Nusselt number with change in s/d. However, with the increase in s/d, the average Nusselt number over the cylinder surface was also found to increase. In this study, the effect of flow confinement below the heated cylinder on heat transfer was also investigated. Both experimental and numerical studies show that confinement at the bottom of the cylinder increases heat transfer.