Turbulent swirling impinging jet arrays: A numerical study on fluid flow and heat transfer

Abstract

Impinging jets are generally utilized as an effective medium of heat and mass transfer. Various stream orientations and swirl effect may be a potential candidate to further improve the heat transfer characteristics. This paper numerically examines two different types of arrays of circular multiple jets and the effect of swirl on jets that impinges vertically onto a flat surface situated at a fixed vertical separation distance H = 2D, D the nozzle diameter and at Reynolds number equal to 11,600. In this regard, three-dimensional simulation was performed using finite volume method whereas turbulence was described by SST k-ω model. The results demonstrate that staggered arrangement ensures better mixing and higher velocity as well as heat transfer. The strength of recirculation for swirl jet is larger than that of non-swirl jet. Maximum pressure coefficient occurs at individual stagnation point of each jet, with a secondary peak between two neighboring jets. Strong heat transfer is predicted to occur at around the stagnation region for each non-swirling jet and between the neighboring jets for swirling jets. Turbulences are intense around the periphery of each jet and they coalesce as it moves downward.