Effect of Jet-to-Target Spacing on Flow and Heat Transfer Characteristics for Swirling Impinging Micro-Slot Jets

The influence of jet-to-target spacing on flow and heat transfer behaviors for swirling impinging micro-slot jets has been extensively studied. In this study, two complete revolutions of the generated helix under the slot nozzle thickness of 1.0 mm constrained the total spiraling length to 290 mm. The range of jet-to-target spacing varied from 1 to 6. The turbulent kinetic energy-epsilon model was employed to make predictions at Reynolds numbers from 5000 to 20000. The results showed that the heat transfer enhancement on the target wall depended on the pacing between the jet and the target. This is the jet flow structure exhibited a notable intensity of high-velocity vortices at the low jet-to-target spacing, whereas the jet flow impingement was abruptly reduced at the high jet-to-target spacing. The heat transfer rate also tended to increase as the Reynolds number increased. In addition, when the jet-to-target spacing was at 1, the average heat transfer value was between 32.9% and 54.2% higher than in other conditions due to high fluid acceleration.