A NUMERICAL STUDY OF STEADY AND UNSTEADYFLOW AND HEAT TRANSFER FROM A CONFINED SLOT JET IMPINGING ON A CONSTANT HEAT FLUX WALL

Abstract

Impinging jets have been used effectively in several applications including films and foods, rapid cooling and heating processes, tempering of glass and metal, drying of papers, coating, and freezing of tissue. In this work, a numerical simulation of steady and unsteady flow and heat transfer due to a confined 2-D slot jet impinging on constant heat flux plate is presented. Two cases of problem were considered. In the first case, jet-to-plate spacing was varied from 2 to 5 at a fixed jet Reynolds number of 500. In the second case, jet Reynolds number was varied from 200 to 750 at fixed jet-to-plate spacing of 5. In the steady regime, the stagnation Nusselt number was found to increase linearly with increasing Reynolds number, and the distribution of heat transfer in the wall jet region was found to be highly influenced by flow characteristics of the jet. A strong correlation between pressure distribution and Nusselt number was noticed. The critical Reynolds number at which the symmetry of the flow in the formation of vortex sheets is highly disrupted was determined. It was observed that, at the critical Reynolds number, the area-averaged heat transfer coefficient is high and influence the drastic changes of the Nusselt number in the unsteady regime.