Numerical Study of Heat Transfer and Flow Characteristics of Nozzle Impingement Jet on Concave Surface by Jet Potential Core Analysis

Impingement jet provides an effective method to enhance the heat transfer process because the heat transfer coefficient is much higher in the stagnation point than that in the forced convection flows. The heat and mass transfer of impingement jet are very complex, influenced by many structure parameters (impingement wall structure, distance between nozzle and target, etc.) and flow parameters. In this paper, commonly turbulence methods were simulated to verify the proper turbulence model based by RANS equation and compared with the experimental data. The results showed that the SST k-ω model has the advantage for concave impingement jet heat transfer process, especially the capacity to predict the phenomenon in the second Nu peak. In this article, the flow and heat transfer characteristics of different H/d and Re were studied, and the mechanism of heat transfer enhancement was analyzed from the point of the jet potential core region length. The analysis results show that the length of the jet core region has great correlation with the surface average Nusselt number. Smaller ξj keep the jet fluid in the potential core region maintain enough energy into the stagnation zone, which causes the stagnation point and local both increase. From H/d=4 to H/d=1, at three different Re conditions, ξj decreases 62%, 61% and 65% while the corresponding Nu increases 25%, 22% and 45%, respectively. © 2022, Science Press. All right reserved.