Impact of blockage ratio on thermal performance of delta-winglet vortex generators

Indri Yaningsih, Agung Tri Wijayanta, Takahiko Miyazaki, Shigeru Koyama

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


The impact of double-sided delta-winglet tape (DWTs) inserts on convective heat transfer and friction behaviors in a tube was experimentally investigated. Three DWTs with ratios of winglet-height (b) to inner tube diameter (di) called blockage ratio (Rb) of 0.28, 0.35 and 0.42 were tested and their performance was compared to that of a longitudinal strip and plain tube under similar test flow conditions. Experiments were conducted over a wide range of flow rates, 3.35 × 10-5-8.33 × 10-5 m3/s, which correspond to 5500 ≥ Reynolds number (Re) ≥ 14,500 in the 14.3 mm i.d. tube. The results revealed that using DWTs dramatically increased the Nusselt number (Nu) by as much as 364.3% and the friction factor (f) by 15.5 times compared with those of a plain tube. Thermal performance (η) increased with a corresponding increase in Rb. The highest thermal performance (η) obtained was 1.4. Showing a notable improvement on the thermal performance of the system, DWTs are proposed as a favorable insert device.

Original languageEnglish
Article number181
JournalApplied Sciences (Switzerland)
Issue number2
Publication statusPublished - Jan 26 2018

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes


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