Effects of Nozzle Configuration on Flow and Heat Transfer of Confined Jet in Semi-Enclosed Space

The quenching deformation of ultra-high-strength steel sheets is a technical challenge in the steel industry. Although air-jet quenching can effectively improve shape quality, it requires substantial energy consumption. How to improve the heat transfer intensity of air jets by improving key components has become the keypoint of using this technology in industry. In this study, a CFD model was established to investigate the impacts of nozzle shapes and jet arrangements on the flow structure, wall heat transfer intensity and wall heat transfer uniformity under the same total flow rate. The results show that the impingement heat transfer could only be realized by adopting a symmetrical nozzle design (including the symmetric nozzle shape and jet arrangement). And the intensity and uniformity of wall heat transfer were hardly affected by the specific symmetrical nozzle shape. Moreover, under the S/B (ratio of slot spacing to slot width) condition adopted in this study, multiple jets did not significantly enhance heat transfer uniformity but instead tended to reduce the overall heat transfer intensity. In this paper, the configuration of the horizontal nozzle with the central single jet was optimal due to its high heat transfer intensity, good heat transfer uniformity and lower energy consumption.