Direct numerical simulations were performed for air flows and related heat transfer in a developing region of the ribbed channel, where five ribs were attached to one wall. Three rib pitch-to-height ratios, Pi/H = 7, 4 and 2, were considered. The Reynolds number based on the bulk velocity and the channel width was 4,560. For the same parameters, simulations were also made for periodic fully developed cases. Although the largest rib pitch, Pi/H = 7, was the best choice for a heat transfer enhancement ratio in the fully developed cases, the enhancement ratio was larger for the smaller values of rib pitch, Pi/H = 4 or Pi/H = 2 in the initial region. Preference of smaller rib spacing in the initial region was found to come from: (1) the pressure drop was kept low due to the modest meandering of the stream lines; (2) downstream ribs were placed immediately behind the upstream ribs being exposed to the thin thermal layer; (3) the turbulent heat transport was active because of the fluctuation based on the Kelvin-Helmholtz type instability in Pi/H = 4 though fluctuation was weak in Pi/H = 2. Therefore, flow structures positively contributed the heat transfer enhancement of Pi/H = 4 and 2 in the developing region, and the smaller values of the rib pitch was recommended to be selected in such situations.
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2010 14th International Heat Transfer Conference
August 8–13, 2010
Washington, DC, USA
Conference Sponsors:
- Heat Transfer Division
ISBN:
978-0-7918-4937-8
PROCEEDINGS PAPER
Turbulent Flow and Heat Transfer in Initial Stage of Ribbed Channel
Takahiro Miura,
Takahiro Miura
Niigata University, Niigata, Niigata, Japan
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Koji Matsubara,
Koji Matsubara
Niigata University, Niigata, Niigata, Japan
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Yoshiyuki Nagai,
Yoshiyuki Nagai
Niigata University, Niigata, Niigata, Japan
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Atsushi Sakurai
Atsushi Sakurai
Niigata University, Niigata, Niigata, Japan
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Takahiro Miura
Niigata University, Niigata, Niigata, Japan
Koji Matsubara
Niigata University, Niigata, Niigata, Japan
Yoshiyuki Nagai
Niigata University, Niigata, Niigata, Japan
Atsushi Sakurai
Niigata University, Niigata, Niigata, Japan
Paper No:
IHTC14-22048, pp. 269-278; 10 pages
Published Online:
March 1, 2011
Citation
Miura, T, Matsubara, K, Nagai, Y, & Sakurai, A. "Turbulent Flow and Heat Transfer in Initial Stage of Ribbed Channel." Proceedings of the 2010 14th International Heat Transfer Conference. 2010 14th International Heat Transfer Conference, Volume 2. Washington, DC, USA. August 8–13, 2010. pp. 269-278. ASME. https://doi.org/10.1115/IHTC14-22048
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