Experimental and LES study of unconfined jet impingement on a smooth flat heated plate with slots of different widths

Abstract

ABSTRACT The present work focuses on the experimental and large-eddy simulation (LES) investigation of fluid flow and heat transfer due to the impingement of an unconfined turbulent slot jet on a smooth flat plate. Three LES sub-grid scale models are validated with the experimental observations for first time in terms effect of slot widths. A detailed parametric study is conducted considering nozzle to plate spacing ratio from 4 to 12, non-dimensional slot width from 0.015 to 0.035, and Reynolds number range from 4000 to 12000. The results show an appreciable change in the stagnation point and along the wall jet Nusselt numbers with the change in Reynolds number, nozzle-to-plate spacing and non-dimensional slot width. No significant effect of nozzle to plate spacing is observed along the wall jet Nusselt number beyond the streamwise location at 0.2. The local Nusselt number increases with an increase in Reynolds number while it decreases with an increase in nondimensional slot width. Comparison of various LES sub-grid models with RANS (k-ω SST) turbulence model is performed. The results show that turbulent kinetic energy plays a major role in enhancing the heat transfer rate. Dissipation of the turbulent kinetic energy increases with an increase in nozzle to plate spacing and non-dimensional slot width. Further, a correlation is proposed for the stagnation point and wall jet region Nusselt numbers in terms of effect of slots width, Reynolds number and non-dimensional nozzle to plate spacing.