Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 3 July 2020
Issue publication date: 10 March 2021
Abstract
Purpose
The purpose of this paper is to numerically study the influence of wall conduction on the heat transfer of supercritical n-decane in the active regenerative cooling channels.
Design/methodology/approach
A horizontally placed rectangular pipe with a solid zone and another one without a solid zone were used. A drastic variation of thermo-physical properties was emphatically addressed. After the verification of mesh and turbulence models comparing with the experimental results, a mesh number of 4.5 M and the low Reynolds number SST k-ω turbulence model were chosen. The solution of the governing equations and the acquisition of the numerical results were executed by the commercial software FLUENT 2020 R1.
Findings
The numerical results indicate that there is a heat transfer deterioration (HTD) potential for the upper wall, lower wall and sidewall with the decrease of mass flux. Due to wall conduction, the distribution of the fluid temperature at spanwise-normal planes becomes uniform and this feature also takes advantage of the relatively uniform transverse velocity. For the streamwise-normal planes, the low fluid temperature appears close to the upper wall at the region near the sidewall and vice versa for the region near the centre. Undoubtedly, the secondary flow at the cross-section plays a crucial role in this process and the relatively cool mainstream is affected by the vortices.
Originality/value
This study warns that the wall conduction must be considered in the practical design and thermal optimization due to the sensibility of thermo-physical properties to the heat flux. The secondary flow caused by the buoyancy force (gravity) plays a significant role in the supercritical heat transfer and mixed convection heat transfer should be further studied.
Keywords
Acknowledgements
This work was sponsored by the National Natural Science Foundation of China (51676163), the National 111 Project under Grant No. B18041, and the Fundamental Research Funds of Shenzhen City (JCYJ20170306155153048). This research work was also financially supported by the China Scholarship Council (CSC) giving Yong Li the opportunity to perform part of his PhD studies at Lund University. The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at LUNARC and partially funded by the Swedish Research Council.
Citation
Li, Y., Xie, G. and Sunden, B.A. (2021), "Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 31 No. 3, pp. 880-896. https://doi.org/10.1108/HFF-02-2020-0115
Publisher
:Emerald Publishing Limited
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