Heat transfer deterioration in upward and downward pipe flows of supercritical n-decane for actively regenerative cooling
File(s)
Accepted version
Author(s)
Li, Yong
Markides, Christos N
Sunden, Bengt
Xie, Gongnan
Type
Journal Article
Abstract
In this paper, we consider the flow and heat transfer behaviour of turbulent upward and downward flows of supercritical n-decane, in order to reveal the features of heat transfer deterioration (HTD) that would be expected in relevant active regenerative cooling systems for scramjet engines. Specific focus is placed on key velocity-field features that appear in these flows. Following the validation of six turbulence models, the SST k-ω and RNG k-ϵ models are found to be suitable for simulating the upward and downward flow cases, respectively. “M” type velocity profiles (a non-monotonicity of the velocity along the radial direction) are observed, which arise due to a spatially-varying interplay between the inertial and viscous forces in the flow domain, while larger velocity gradients in the buffer layer are also observed that contribute to the phenomenon of HTD. Furthermore, it is found that the secondary flows as well as the different mass fluxes that arise due to the velocity increase from the wall to the flow core zone (i.e., the influencing range and intensity of cross-sectional kinetic energy), respectively, are observed in the HTD development region, as well as the HTD peak area and degradation regions. A zone of higher thermal diffusion appears in the near-wall region, which acts as a thermal barrier and contributes to HTD.
Date Issued
2021-10
Date Acceptance
2021-05-13
Citation
International Journal of Thermal Sciences, 2021, 168, pp.1-13
ISSN
1290-0729
Publisher
Elsevier BV
Start Page
1
End Page
13
Journal / Book Title
International Journal of Thermal Sciences
Volume
168
Copyright Statement
© 2021 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Identifier
https://www.sciencedirect.com/science/article/pii/S1290072921002301?via%3Dihub
Subjects
0102 Applied Mathematics
0913 Mechanical Engineering
0915 Interdisciplinary Engineering
Mechanical Engineering & Transports
Publication Status
Published
Article Number
107066
Date Publish Online
2021-05-29