CFD Study of Behavior of Transition Flow in Distinct Tubes of Miscellaneous Tape Insertions

Abstract

Application of transition flow can be found in several processes and systems. It has been revealed through findings from various researchers that the values of Reynolds numbers at which transition flow occurs vary. In the current work, investigations were numerically conducted by Fluent on transition of water flow in three assorted plain tubes fitted with miscellaneous tape insertions. They are plain tube with crossed-axes-circle-cut tape insert (C-C tube), plain tube with crossed-axes-triangle-cut tape insert (C-T tube), and plain tube with crossed-axes-ellipse-cut tape insert (C-E tube). The focus of the work is to explore the influence of the tape insertion on commencement and finish of transition flow in the tubes with respect to the Reynolds number of the flow. The Reynolds number (Re) taken into account for the transition flow is 2,150≤Re≤4,650, and the variation of Shear-Stress Transport κ-ω model that deals with transition flow was utilized. The results showed that transition flow starts at Re=2,300 and finishes at Re=4,400 in C-T tube, starts at Re=2,780 and finishes at Re=4,610 in C-C tube, but starts at Re=2,550 and finishes at Re=4,500 in C-E tube. The Nusselt number in C-T tube is 19.3% to 45.6% higher than that in C-C tube, but the Nusselt number in C-T tube is 3.6% to 28.3% more than that in C-E tube. The friction factor in C-T tube is 2.15% to 4.56% higher than that in C-C tube; the friction factor in C-T tube is 0.83% to 3.33% more than that in C-E tube. These results indicate that for the case of the tubes considered in this work, the C-T tube, which is the first one in which transition flow commences and ends, has the highest Nusselt number, but C-C tube, in which transition flow commences and finishes last, has the least Nusselt number. Interestingly, the same phenomenon applies to the friction factor. Doi: 10.28991/HIJ-2022-03-02-02 Full Text: PDF

Keywords

• heat transfer
• transition flow
• thermo-hydraulic
• induced tubes
• friction factor
• cfd.