Line fountain behavior at low-Reynolds number

✍ Scribed by N. Srinarayana; N. Williamson; S.W. Armfield; Wenxian Lin

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 773 KB
• Volume: 53
• Category: Article
• ISSN: 0017-9310
• DOI: 10.1016/j.ijheatmasstransfer.2009.12.048

✦ Synopsis

In this paper, we present line fountain behavior at low-Reynolds numbers obtained by experiments. The experiments are conducted over the range of Reynolds number 2:1 K Re K 127 and Froude number 0:4 K Fr K 42. It is observed that the fountain behavior can be categorized broadly into four regimes: the steady; flapping; laminar mixing; and jet-type mixing behavior, at full development. The critical Froude number for transition from a steady to unsteady flow varies with the Reynolds number. For Re J 60, the transition is independent of Re and is well described by the Fr $ 1:0 line. Over the range 10 < Re K 50, the transition can be approximated by a constant FrRe 2=3 line. For Re K 10, there is a higher dependency on the Reynolds number with a very sharp increase in the critical Froude number and it is hypothesized that the demarcation line follows Fr $ Re Àn , where n % 2-4. The fountain exhibits flapping behavior in the range 13Re À2=3 K Fr K 37Re À2=3 . These observed fountain behaviors are mapped on to a Re-Fr plot. In addition, the observed, non-dimensionalised fountain height z m is found to be in reasonable agreement with previous results on laminar line fountains. In particular, the experimental results confirm the scaling z m $ FrRe À1=2 in the steady regime which was obtained previously by scaling analysis.