Analysis of the three-dimensional swirling and non-swirling jet impingement using a turbulence model with cross-diffusion correction

Abstract

Three-dimensional swirling impinging jets using the aerodynamic swirl generator are carried out to understand the pure effects of swirl. A shear stress transport model with cross-diffusion correction (SSTCD) is validated for the above flows with the documented experiments. Based on the good performance of the SSTCD model, a detailed flow analysis for Re = 23,000 and swirl numbers of 0 and 0.45 at nozzle-plate spacings of 2 and 6 is presented in terms of the flow structures, mean velocity field, wall shear stress and heat transfer. The results show that the strength of the swirl is reduced with increasing the nozzle-plate spacing near the wall. On the contrary, the effect of swirl on both flow fields and heat transfer is more evident at high nozzle-plate spacing, leading to a broader impact region along the impinging plate. However, downstream, the effect of swirl can be ignored for the above fields at all nozzle-plate spacings. In addition, the swirl motion contributes to high turbulence but the heat transfer rate still decreases with an increase of swirl number. Meanwhile, the uniformity of heat transfer is improved by the swirl motion for both nozzle-plate spacings, except that near the stagnation region at H/D = 2. It is also found that this improvement depends on the Reynolds number.