Aerothermal performance improvement by cross and X ribbed stripes

Shyy Woei Chang, Ching Hui Chen, Yong En Lu

研究成果: Article同行評審

2 引文 斯高帕斯(Scopus)

摘要

The incentive to save energy in heat exchangers has led to enhanced thermal performance in ducted flows, achieved via inserts designed to increase the heat transfer efficiency and efficacy. We introduce a novel approach using cross and X stripe inserts, roughened by 90° and 45° ribs, to enhance the structural integrity and heat transfer rate of the duct. Additionally, the incorporation of edged notches aims to improve aerothermal performance by directing flow traction away from the recirculating cell behind a rib, thereby reducing the drag. Utilizing the infrared thermography method, this research quantifies the full-field Nusselt number distributions for 34 enhanced ducts at Reynolds numbers 5,000–25,000. The outcomes of flow simulations elucidate the underlying mechanisms of aerothermal performance enhancement afforded by these inserts. These enhancements result from the combined effects of increased turbulence intensity, fluid mixing, and rib-induced multicellular vortices, which improve the synergy between fluid velocity and temperature gradient vectors, thereby optimizing heat transfer. Quantitatively, the Nusselt numbers (friction factors) for ducts with cross or X ribbed stripes increase significantly. For cross stripes, the ranges increase by 1.25–3.17 times (3.14–21.75 for friction factors), and for X stripes, 1.29–3.39 times (6.58–43.41 for friction factors), compared with the Dittus–Boelter (Blasius) standards. Notably, the aerothermal performance index for ducts featuring notched cross stripes with 45° ribs and a rib pitch-to-height ratio of 10 reaches 1.47 to 1.11, though this decreases with increasing Reynolds number. Furthermore, the study presents empirical correlations to assess the average Nusselt number and friction factor in a square duct equipped with either cross or X ribbed stripes.

原文English
文章編號109126
期刊International Journal of Mechanical Sciences
271
DOIs
出版狀態Published - 2024 6月 1

All Science Journal Classification (ASJC) codes

  • 土木與結構工程
  • 一般材料科學
  • 凝聚態物理學
  • 航空工程
  • 海洋工程
  • 材料力學
  • 機械工業
  • 應用數學

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