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A numerical investigation of dimple effects on internal heat transfer enhancement of a double wall cooling structure with jet impingement

Lei, Luo LU ; Wang, Chenglong LU ; Wang, Lei LU ; Sunden, Bengt Ake LU and Wang, Sangtao (2016) In International Journal of Numerical Methods for Heat and Fluid Flow 26(7). p.2175-2197
Abstract

Purpose - The dimple is adopted into a double wall cooling structure which is widely used in hot gas components to increase the heat transfer effects with relatively low pressure drop penalty. The purpose of this paper is to study the effect of dimple depth and dimple diameter on the target surface heat transfer and the inlet to outlet friction factor. Design/methodology/approach - The study is carried out by using the numerical simulations. The impingement flow is directly impinging on the dimple and released from the film holes after passing the double wall chamber. The ratio between dimple depth and dimple diameter is varied from 0 to 0.4 and the ratio between dimple diameter and impingement hole diameter is ranging from 0.5 to 3.... (More)

Purpose - The dimple is adopted into a double wall cooling structure which is widely used in hot gas components to increase the heat transfer effects with relatively low pressure drop penalty. The purpose of this paper is to study the effect of dimple depth and dimple diameter on the target surface heat transfer and the inlet to outlet friction factor. Design/methodology/approach - The study is carried out by using the numerical simulations. The impingement flow is directly impinging on the dimple and released from the film holes after passing the double wall chamber. The ratio between dimple depth and dimple diameter is varied from 0 to 0.4 and the ratio between dimple diameter and impingement hole diameter is ranging from 0.5 to 3. The Reynolds number is between 10,000 and 70,000. Results of the target surface Nusselt number, friction factor and flow structures are included. For convenience of comparison, the double wall cooling structure without the dimple is considered as the baseline. Findings - It is found that the dimple can effectively enhance the target surface heat transfer due to thinning of the flow boundary layer and flow reattachment as well as flow recirculation outside the dimple near the dimple rim especially for the large Re number condition. However, the stagnation point heat transfer is reduced. It is also found that for a large dimple depth or large dimple diameter, a salient heat transfer reduction occurs for the toroidal vortex. The thermal performance indicates that the intensity of the heat transfer enhancement depends upon the dimple depth and dimple diameter Originality/value - This is the first time to adopt a dimple into a double wall cooling structure. It suggests that the target surface heat transfer in a double wall cooling structure can be increased by the use of the dimple. However, the heat transfer characteristic is sensitive for the different dimple diameter and dimple depth which may result in a different flow behavior.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Dimple, Double wall cooling structure, Friction factor, Heat transfer, Jet impingement, Thermal performance
in
International Journal of Numerical Methods for Heat and Fluid Flow
volume
26
issue
7
pages
23 pages
publisher
Emerald Group Publishing Limited
external identifiers
  • scopus:84987809984
  • wos:000386030700012
ISSN
0961-5539
DOI
10.1108/HFF-02-2015-0081
language
English
LU publication?
yes
id
eb97e48d-b565-4ca2-b2c9-5670284a6f6a
date added to LUP
2017-02-22 13:50:02
date last changed
2017-09-18 11:34:30
@article{eb97e48d-b565-4ca2-b2c9-5670284a6f6a,
  abstract     = {<p>Purpose - The dimple is adopted into a double wall cooling structure which is widely used in hot gas components to increase the heat transfer effects with relatively low pressure drop penalty. The purpose of this paper is to study the effect of dimple depth and dimple diameter on the target surface heat transfer and the inlet to outlet friction factor. Design/methodology/approach - The study is carried out by using the numerical simulations. The impingement flow is directly impinging on the dimple and released from the film holes after passing the double wall chamber. The ratio between dimple depth and dimple diameter is varied from 0 to 0.4 and the ratio between dimple diameter and impingement hole diameter is ranging from 0.5 to 3. The Reynolds number is between 10,000 and 70,000. Results of the target surface Nusselt number, friction factor and flow structures are included. For convenience of comparison, the double wall cooling structure without the dimple is considered as the baseline. Findings - It is found that the dimple can effectively enhance the target surface heat transfer due to thinning of the flow boundary layer and flow reattachment as well as flow recirculation outside the dimple near the dimple rim especially for the large Re number condition. However, the stagnation point heat transfer is reduced. It is also found that for a large dimple depth or large dimple diameter, a salient heat transfer reduction occurs for the toroidal vortex. The thermal performance indicates that the intensity of the heat transfer enhancement depends upon the dimple depth and dimple diameter Originality/value - This is the first time to adopt a dimple into a double wall cooling structure. It suggests that the target surface heat transfer in a double wall cooling structure can be increased by the use of the dimple. However, the heat transfer characteristic is sensitive for the different dimple diameter and dimple depth which may result in a different flow behavior.</p>},
  author       = {Lei, Luo and Wang, Chenglong and Wang, Lei and Sunden, Bengt Ake and Wang, Sangtao},
  issn         = {0961-5539},
  keyword      = {Dimple,Double wall cooling structure,Friction factor,Heat transfer,Jet impingement,Thermal performance},
  language     = {eng},
  number       = {7},
  pages        = {2175--2197},
  publisher    = {Emerald Group Publishing Limited},
  series       = {International Journal of Numerical Methods for Heat and Fluid Flow},
  title        = {A numerical investigation of dimple effects on internal heat transfer enhancement of a double wall cooling structure with jet impingement},
  url          = {http://dx.doi.org/10.1108/HFF-02-2015-0081},
  volume       = {26},
  year         = {2016},
}