Flow visualization of annular and delta winlet vortex generators in fin-and-tube heat exchanger application

Chi-Chuan Wang*, Jerry Lo, Yur Tsai Lin, Chung Szu Wei

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Scopus citations


This study presents flow visualization and frictional results of enlarged fin-and-tube heat exchangers with and without the presence of vortex generators. Two types of vortex generators and a plain fin geometry were examined in this study. For plain fin geometry at Re = 500, the horseshoe vortex generated by the tube row is not so pronounced, and the horseshoe vortex separates into streams as it flows across the second row and consequently loses its vortical strength. This phenomenon may supports the "maximum phenomenon" in low Reynolds number region reported by previous studies. With the presence of annular vortex generator, the presence of a pair of longitudinal vortices formed behind the tube is seen. The strength of the counter-rotating vortices increases with the annular height and the strength of the longitudinal vortices is so strong that may swirl with the horseshoe vortices and other flow stream. For the same winlet height, the delta winlet shows more intensely vortical motion and flow unsteadiness than those of annular winlet. This eventually leads to a better mixing phenomenon. However, it is interesting to know that the corresponding pressure drops of the delta winlet are lower than those of annular winlet. Compared to the plain fin geometry, the penalty of additional pressure drops of the proposed vortex generators is relatively insensitive to change of Reynolds number.

Original languageEnglish
Pages (from-to)3803-3815
Number of pages13
JournalInternational Journal of Heat and Mass Transfer
Issue number18
StatePublished - 17 Jun 2002


  • Fin-and-tube heat exchanger
  • Vortex generator

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