Thermal streak spacing in fully developed duct flow with different Reynolds and Prandtl numbers

Sharma, Mohit Pramod (author), Tiselj, Iztok (author), Kren, Jan (author), Mikuž, Blaž (author), Cizelj, Leon (author)

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 %.

• Language: English
• 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
• Year: 2023
• Number of pages: Str. 2105–2116
• Numbering: Vol. 59, iss. 11
• PID: 20.500.12556/RUL-152539
• UDC: 621.039
• ISSN on article: 1432-1181
• DOI: 10.1007/s00231-023-03399-z
• COBISS.SI-ID: 159282435
• Publication date in RUL: 27.11.2023

Record is a part of a journal

• Title: Heat and mass transfer
• Shortened title: Heat mass transf.
• Publisher: Springer Nature
• ISSN: 1432-1181
• COBISS.SI-ID: 512810265

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• 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.

Projects

• 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