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Flow structure and heat transfer in a square passage with offset mid-truncated ribs

Xie, Gongnan; Liu, Jian; Ligrani, Phillip M. and Sundén, Bengt LU (2014) In International Journal of Heat and Mass Transfer 71. p.44-56
Abstract
The enhancement of heat transfer attributed from rib turbulators relative to the increased pressure drop in the channel is a crucial design parameter. Thus, the design of the truncated ribs (whose length is less than the passage width) provides options to address such cooling requirements when the pressure loss is a critical factor. Considering different types of truncated ribs, mid-truncated ribs (which are truncated in the central part of the rib) have been proved to show better thermal performance than other types of truncated ribs. A numerical study of mid-truncated ribs with different offset placements or angles on turbulent heat transfer inside a non-rotating cooling passage of a gas turbine blade is performed for inlet Reynolds... (More)
The enhancement of heat transfer attributed from rib turbulators relative to the increased pressure drop in the channel is a crucial design parameter. Thus, the design of the truncated ribs (whose length is less than the passage width) provides options to address such cooling requirements when the pressure loss is a critical factor. Considering different types of truncated ribs, mid-truncated ribs (which are truncated in the central part of the rib) have been proved to show better thermal performance than other types of truncated ribs. A numerical study of mid-truncated ribs with different offset placements or angles on turbulent heat transfer inside a non-rotating cooling passage of a gas turbine blade is performed for inlet Reynolds number ranging from 10,000 to 50,000. The overall performance characteristics of six different types of mid-truncated ribbed arrangements are also compared: Cases A1, A2, A3 utilize mid-truncated spanwise ribs with different relative rib stagger positions at different spanwise locations; Cases B, C, D utilize mid-truncated angled ribs with the ribs oriented at +/- 45 degrees (Case B), +45 degrees/+45 degrees (Case C), and +/- 135 degrees (Case D). In all cases, a gap is present between the ribs placed on opposite spanwise parts of the channel, to provide the mid-truncation. It is found that the 135 degrees mid-truncated rib (Case D) has the highest heat transfer coefficient, while the 90 degrees mid-truncated ribs with no offset placement (Case A1) behave best in reducing pressure loss penalty. Although Case A shows larger heat transfer augmentation, Case D is advantageous for augmenting side-wall heat transfer when the pressure loss is considered and the Reynolds number is comparatively large. Case C exhibits the best overall thermal performance over the largest range of experimental conditions when the pressure drop is also considered. Staggered arrangement for 90 degrees mid-truncated ribs can enhance heat transfer efficiently and makes a good overall performance at low Reynolds numbers. Case A1 can be used in practical operation because of reduced weight and good thermal performance at high Reynolds numbers. This is the first study on various offset mid-truncated ribs aiming to improve the heat transfer of turbine blade internal cooling passages with reduced pressure loss penalty. (C) 2013 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Heat transfer, Mid-truncated rib, Offset placement and angle, Recirculating flow, Reattachment, Numerical prediction
in
International Journal of Heat and Mass Transfer
volume
71
pages
44 - 56
publisher
Pergamon
external identifiers
  • wos:000332438400006
  • scopus:84891542612
ISSN
0017-9310
DOI
10.1016/j.ijheatmasstransfer.2013.12.005
language
English
LU publication?
yes
id
519b5af8-cc3a-44cc-9571-53ace9c55d3d (old id 4414240)
date added to LUP
2014-04-29 15:46:32
date last changed
2017-10-01 03:09:10
@article{519b5af8-cc3a-44cc-9571-53ace9c55d3d,
  abstract     = {The enhancement of heat transfer attributed from rib turbulators relative to the increased pressure drop in the channel is a crucial design parameter. Thus, the design of the truncated ribs (whose length is less than the passage width) provides options to address such cooling requirements when the pressure loss is a critical factor. Considering different types of truncated ribs, mid-truncated ribs (which are truncated in the central part of the rib) have been proved to show better thermal performance than other types of truncated ribs. A numerical study of mid-truncated ribs with different offset placements or angles on turbulent heat transfer inside a non-rotating cooling passage of a gas turbine blade is performed for inlet Reynolds number ranging from 10,000 to 50,000. The overall performance characteristics of six different types of mid-truncated ribbed arrangements are also compared: Cases A1, A2, A3 utilize mid-truncated spanwise ribs with different relative rib stagger positions at different spanwise locations; Cases B, C, D utilize mid-truncated angled ribs with the ribs oriented at +/- 45 degrees (Case B), +45 degrees/+45 degrees (Case C), and +/- 135 degrees (Case D). In all cases, a gap is present between the ribs placed on opposite spanwise parts of the channel, to provide the mid-truncation. It is found that the 135 degrees mid-truncated rib (Case D) has the highest heat transfer coefficient, while the 90 degrees mid-truncated ribs with no offset placement (Case A1) behave best in reducing pressure loss penalty. Although Case A shows larger heat transfer augmentation, Case D is advantageous for augmenting side-wall heat transfer when the pressure loss is considered and the Reynolds number is comparatively large. Case C exhibits the best overall thermal performance over the largest range of experimental conditions when the pressure drop is also considered. Staggered arrangement for 90 degrees mid-truncated ribs can enhance heat transfer efficiently and makes a good overall performance at low Reynolds numbers. Case A1 can be used in practical operation because of reduced weight and good thermal performance at high Reynolds numbers. This is the first study on various offset mid-truncated ribs aiming to improve the heat transfer of turbine blade internal cooling passages with reduced pressure loss penalty. (C) 2013 Elsevier Ltd. All rights reserved.},
  author       = {Xie, Gongnan and Liu, Jian and Ligrani, Phillip M. and Sundén, Bengt},
  issn         = {0017-9310},
  keyword      = {Heat transfer,Mid-truncated rib,Offset placement and angle,Recirculating flow,Reattachment,Numerical prediction},
  language     = {eng},
  pages        = {44--56},
  publisher    = {Pergamon},
  series       = {International Journal of Heat and Mass Transfer},
  title        = {Flow structure and heat transfer in a square passage with offset mid-truncated ribs},
  url          = {http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.12.005},
  volume       = {71},
  year         = {2014},
}