Effect of temperature and velocity inlet conditions at the diffusers on the thermal and dynamic behavior of an impacting swirling multi-jet system

Abstract

This study concerns the numerical simulation of a system of swirling turbulent jets impacting a flat plate, by two numerical models of the closure of the Navier Stokes equations (k-ω sst). The jet impact technique is widely applied in the field of heating, drying and cooling of industrial objects. The experimental test bench comprising a diffuser of diameter D, impacting the perpendicular plate, such that the impact distance H = 4D. The swirl is obtained by a swirl generator, made up of 12 fins arranged at 60° from the vertical, placed just at the outlet of the diffuser. The temperature of the swirling jets blowing on the plate is measured with a VELOCICALC PLUS portable thermo-anemometer device, in different stations. It is noted that this diffuser configuration having balanced inlet temperatures (T, T, T), gives a uniform distribution of temperature and velocity on the surface of the plate. This temperature distribution results from a 95% spread of homogenization of plate heat transfer. The (k-ω sst) model gave temperature and velocity profiles that coincide with those of the experimental results. By way of comparison, the (k-ω sst) model better predicts impacting jets, particularly in fluctuating zones. The latter remains a relatively better numerical simulation tool in terms of quality.