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Numerical predictions of augmented heat transfer of an internal blade tip-wall by hemispherical dimples

Xie, Gongnan LU and Sundén, Bengt LU (2010) In International Journal of Heat and Mass Transfer 53(25-26). p.5639-5650
Abstract
The heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is increased. Improved cooling methods are therefore needed for the turbine blades to ensure a long durability and safe operation. The blade tip region is exposed to very hot gas flow, and suffers high local thermal loads due to the external tip leakage flow. A common way to cool the tip is to design serpentine passages with 180 turn under the blade tip-cap taking advantage of the three-dimensional turning effect and impingement. Increased internal convective cooling is therefore required to increase the blade tip lifetime. In this paper, augmented heat transfer of a blade tip with internal hemispherical dimples has been investigated... (More)
The heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is increased. Improved cooling methods are therefore needed for the turbine blades to ensure a long durability and safe operation. The blade tip region is exposed to very hot gas flow, and suffers high local thermal loads due to the external tip leakage flow. A common way to cool the tip is to design serpentine passages with 180 turn under the blade tip-cap taking advantage of the three-dimensional turning effect and impingement. Increased internal convective cooling is therefore required to increase the blade tip lifetime. In this paper, augmented heat transfer of a blade tip with internal hemispherical dimples has been investigated numerically. The computational models consist of two-pass channels with 180 turn and arrays of dimples depressed on the internal tip-cap. Turbulent convective heat transfer between the fluid and dimples, and heat conduction within dimples and tip are simultaneously computed. The inlet Reynolds number is ranging from 100,000 to 600,000. Details of the 3D fluid flow and heat transfer over the tip-walls are presented. Comparisons of the overall performance of the models are presented. It is found that due to the combination of turning impingement and dimple-induced advection flow, the heat transfer coefficient of the dimpled tip is up to two times higher than that of a smooth tip with less than 5% pressure drop penalty. It is suggested that the use of dimples is suitable for augmenting blade tip cooling to achieve an optimal balance between thermal and mechanical design requirements. (C) 2010 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Computation, Active area, Heat transfer, Tip-wall, Dimples
in
International Journal of Heat and Mass Transfer
volume
53
issue
25-26
pages
5639 - 5650
publisher
Pergamon
external identifiers
  • wos:000283907700002
  • scopus:77957316009
ISSN
0017-9310
DOI
10.1016/j.ijheatmasstransfer.2010.08.019
language
English
LU publication?
yes
id
e3761082-ad6c-459d-863f-b211ca551541 (old id 1753241)
date added to LUP
2010-12-29 14:26:04
date last changed
2018-05-29 10:13:06
@article{e3761082-ad6c-459d-863f-b211ca551541,
  abstract     = {The heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is increased. Improved cooling methods are therefore needed for the turbine blades to ensure a long durability and safe operation. The blade tip region is exposed to very hot gas flow, and suffers high local thermal loads due to the external tip leakage flow. A common way to cool the tip is to design serpentine passages with 180 turn under the blade tip-cap taking advantage of the three-dimensional turning effect and impingement. Increased internal convective cooling is therefore required to increase the blade tip lifetime. In this paper, augmented heat transfer of a blade tip with internal hemispherical dimples has been investigated numerically. The computational models consist of two-pass channels with 180 turn and arrays of dimples depressed on the internal tip-cap. Turbulent convective heat transfer between the fluid and dimples, and heat conduction within dimples and tip are simultaneously computed. The inlet Reynolds number is ranging from 100,000 to 600,000. Details of the 3D fluid flow and heat transfer over the tip-walls are presented. Comparisons of the overall performance of the models are presented. It is found that due to the combination of turning impingement and dimple-induced advection flow, the heat transfer coefficient of the dimpled tip is up to two times higher than that of a smooth tip with less than 5% pressure drop penalty. It is suggested that the use of dimples is suitable for augmenting blade tip cooling to achieve an optimal balance between thermal and mechanical design requirements. (C) 2010 Elsevier Ltd. All rights reserved.},
  author       = {Xie, Gongnan and Sundén, Bengt},
  issn         = {0017-9310},
  keyword      = {Computation,Active area,Heat transfer,Tip-wall,Dimples},
  language     = {eng},
  number       = {25-26},
  pages        = {5639--5650},
  publisher    = {Pergamon},
  series       = {International Journal of Heat and Mass Transfer},
  title        = {Numerical predictions of augmented heat transfer of an internal blade tip-wall by hemispherical dimples},
  url          = {http://dx.doi.org/10.1016/j.ijheatmasstransfer.2010.08.019},
  volume       = {53},
  year         = {2010},
}