Advanced

Predictions of Enhanced Heat Transfer of an Internal Blade Tip-Wall With Hemispherical Dimples or Protrusions

Xie, Gongnan LU ; Sundén, Bengt LU and Wang, Qiuwang (2011) In Journal of Turbomachinery 133(4).
Abstract
The blade tip region encounters high thermal loads because of the hot gas leakage flows, and it must therefore be cooled to ensure a long durability and safe operation. A common way to cool a blade tip is to design serpentine passages with 180 deg turns under the blade tip-cap inside the turbine blade. Improved internal convective cooling is therefore required to increase the blade tip lifetime. Dimples and protrusions are well recognized as effective devices to augment heat transfer in various applications. In this paper, enhanced heat transfer of an internal blade tip-wall has been predicted numerically. The computational models consist of a two-pass channel with a 180 deg turn and arrays of hemispherical dimples or protrusions... (More)
The blade tip region encounters high thermal loads because of the hot gas leakage flows, and it must therefore be cooled to ensure a long durability and safe operation. A common way to cool a blade tip is to design serpentine passages with 180 deg turns under the blade tip-cap inside the turbine blade. Improved internal convective cooling is therefore required to increase the blade tip lifetime. Dimples and protrusions are well recognized as effective devices to augment heat transfer in various applications. In this paper, enhanced heat transfer of an internal blade tip-wall has been predicted numerically. The computational models consist of a two-pass channel with a 180 deg turn and arrays of hemispherical dimples or protrusions internally mounted on the tip-wall. Inlet Reynolds numbers are in the range of 100,000-600,000. The computations are three dimensional, steady, incompressible, and nonrotating. The overall performance of the two-pass channels is also evaluated. It is found that due to the combination of turning impingement and protrusion crossflow or dimple advection, the heat transfer coefficient of the augmented tip is a factor of 2.0 higher than that of a smooth tip. This augmentation is achieved at the cost of a penalty of pressure drop by around 5%. By comparing the present dimples' or protrusions' performance with others in previous works, it is found that the augmented tips show the best performance, and the dimpled or protruded tips are superior to those pin-finned tips when the active area enhancement is excluded. It is suggested that dimples and protrusions can be used to enhance blade tip heat transfer and hence improve blade tip cooling. [DOI: 10.1115/1.4002963] (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Turbomachinery
volume
133
issue
4
publisher
American Society Of Mechanical Engineers (ASME)
external identifiers
  • wos:000289956200005
  • scopus:79954578662
ISSN
1528-8900
DOI
10.1115/1.4002963
language
English
LU publication?
yes
id
153b2c37-77e6-4425-9696-dcbf25197d36 (old id 1964310)
date added to LUP
2011-05-23 15:41:45
date last changed
2017-06-25 03:04:39
@article{153b2c37-77e6-4425-9696-dcbf25197d36,
  abstract     = {The blade tip region encounters high thermal loads because of the hot gas leakage flows, and it must therefore be cooled to ensure a long durability and safe operation. A common way to cool a blade tip is to design serpentine passages with 180 deg turns under the blade tip-cap inside the turbine blade. Improved internal convective cooling is therefore required to increase the blade tip lifetime. Dimples and protrusions are well recognized as effective devices to augment heat transfer in various applications. In this paper, enhanced heat transfer of an internal blade tip-wall has been predicted numerically. The computational models consist of a two-pass channel with a 180 deg turn and arrays of hemispherical dimples or protrusions internally mounted on the tip-wall. Inlet Reynolds numbers are in the range of 100,000-600,000. The computations are three dimensional, steady, incompressible, and nonrotating. The overall performance of the two-pass channels is also evaluated. It is found that due to the combination of turning impingement and protrusion crossflow or dimple advection, the heat transfer coefficient of the augmented tip is a factor of 2.0 higher than that of a smooth tip. This augmentation is achieved at the cost of a penalty of pressure drop by around 5%. By comparing the present dimples' or protrusions' performance with others in previous works, it is found that the augmented tips show the best performance, and the dimpled or protruded tips are superior to those pin-finned tips when the active area enhancement is excluded. It is suggested that dimples and protrusions can be used to enhance blade tip heat transfer and hence improve blade tip cooling. [DOI: 10.1115/1.4002963]},
  author       = {Xie, Gongnan and Sundén, Bengt and Wang, Qiuwang},
  issn         = {1528-8900},
  language     = {eng},
  number       = {4},
  publisher    = {American Society Of Mechanical Engineers (ASME)},
  series       = {Journal of Turbomachinery},
  title        = {Predictions of Enhanced Heat Transfer of an Internal Blade Tip-Wall With Hemispherical Dimples or Protrusions},
  url          = {http://dx.doi.org/10.1115/1.4002963},
  volume       = {133},
  year         = {2011},
}