Numerical study on thermal-hydraulic characteristics of streamwise-interrupted flying-wing finned tubes

To improve the thermal-hydraulic performance, this study conducted numerical studies on streamwise-interrupted flying-wing finned tubes utilising both single- and double-channel interruption modes. The interruptions varied in width from 0.5 to 10 mm and were strategically positioned in nine distinct locations along the flow direction. The RNG k-ε turbulence model was applied for viscous flow simulation. The findings reveal that fin interruptions create a “breakpoint thermal expansion effect” at specific locations, enhancing heat transfer downstream while diminishing it upstream. For the single-channel interruption mode with a centrally positioned interruption channel, a 5–6 mm width is optimal at a low air velocity (150 Pa total pressure drop and a Reynolds number of 1282.31 for the continuous flying-wing finned tubes). However, at high air velocities (550 Pa total pressure drop and a Reynolds number of 2944.91), interruption is unnecessary. In both modes, standardising the interruption channel width to 2 mm is more effective when the interruptions are placed closer to the downstream end, as opposed to an even distribution. This study provides valuable insights for enhancing the thermal-hydraulic performance of flying-wing finned tubes and similar continuous-finned designs through strategic flow-channel interruptions.