Thermal streak spacing in fully developed duct flow with different Reynolds and Prandtl numbers
ID Sharma, Mohit Pramod (Author), ID Tiselj, Iztok (Author), ID Kren, Jan (Author), ID Mikuž, Blaž (Author), ID Cizelj, Leon (Author)

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The present study investigates the behaviour of thermal streaks on a heated foil which is cooled with turbulent flow in a square duct channel. Real-time infrared thermography is used to visualize and measure the spacing between the thermal streaks. A stainless-steel foil with a thickness of 25 microns is cooled by water. The experiments were performed in a range of Reynolds numbers from 5000 to 20000 and Prandtl numbers from 3 to 7. The mean temperature, root-mean-square of temperature and autocorrelation function have been calculated and used to measure the average thermal streak spacing and power spectra in the spanwise and streamwise directions. The root mean square temperature was 0.3 °C to 0.5 °C which corresponds to roughly 10% of the mean temperature difference between foil and water. The uncertainty in mean temperature difference and root mean square temperature was around 5% and 10%, respectively. The measured thermal streak spacing was 100 wall unit to 180 wall unit under the present experimental range. The uncertainty in measured thermal streak spacing was around 2.5%. The effects of Reynolds number, Prandtl number and heat flux on the thermal streak spacing and also on the statistics of the temperature field have been presented and discussed in this paper. A new correlation has been proposed to predict the dimensionless thermal streak spacing. The error in the prediction is estimated within ± 15 %.

Keywords:thermal streaks, thermal streak spacing, Reynolds number, Prandtl number, heat flux
Work type:Article
Typology:1.01 - Original Scientific Article
Organization:FMF - Faculty of Mathematics and Physics
Publication status:Published
Publication version:Version of Record
Number of pages:Str. 2105–2116
Numbering:Vol. 59, iss. 11
PID:20.500.12556/RUL-152539 This link opens in a new window
ISSN on article:1432-1181
DOI:10.1007/s00231-023-03399-z This link opens in a new window
COBISS.SI-ID:159282435 This link opens in a new window
Publication date in RUL:27.11.2023
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Record is a part of a journal

Title:Heat and mass transfer
Shortened title:Heat mass transf.
Publisher:Springer Nature
COBISS.SI-ID:512810265 This link opens in a new window


License:CC BY 4.0, Creative Commons Attribution 4.0 International
Description:This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.


Funder:ARRS - Slovenian Research Agency
Project number:L2-9210
Name:Raziskave turbulentnega prenosa toplote v kanalu z naprednimi eksperimentalnimi in računskimi metodami

Funder:ARRS - Slovenian Research Agency
Project number:P2-0026
Name:Reaktorska tehnika

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