Scale effect of micro ribs on the turbulent transport in an internal cooling channel
(2024) In Physics of Fluids 36(2).- Abstract
Owing to the limited supply and pressure margin in the air system, a cooling technique providing efficient heat transfer with lower flow loss is highly desirable for gas turbine blades. Microscale ribs have promised to be a potential cooling candidate. In this work, large eddy simulations are implemented to reveal the scale effect of micro ribs on the near-wall turbulent transport in a cooling channel. Considering a mechanistic study and practical applications, both single-rib and rib-array arrangements are studied with a wide range of dimensionless viscous-scaled rib heights involving the entire boundary layer. The results indicate that the rib-induced destruction and regeneration of coherent structures are, respectively, responsible... (More)
Owing to the limited supply and pressure margin in the air system, a cooling technique providing efficient heat transfer with lower flow loss is highly desirable for gas turbine blades. Microscale ribs have promised to be a potential cooling candidate. In this work, large eddy simulations are implemented to reveal the scale effect of micro ribs on the near-wall turbulent transport in a cooling channel. Considering a mechanistic study and practical applications, both single-rib and rib-array arrangements are studied with a wide range of dimensionless viscous-scaled rib heights involving the entire boundary layer. The results indicate that the rib-induced destruction and regeneration of coherent structures are, respectively, responsible for the weakened momentum transport and enhanced heat transport in the near-wall region. Using tiny ribs, regenerated quasi-streamwise vortices are mainly located in the buffer layer. The resulting turbulence burst greatly enhances wall heat transfer while keeping a lower flow loss due to the weak form drag. Regenerated hairpin vortices using tall ribs are activated in the log-law layer and intensively interact with mainstream. Along with improved wall heat transfer, the significant form drag results in a remarkably high flow loss. Accordingly, heat transfer and flow loss show different dependencies on the rib height, which contributes to an optimum height interval of ribs (e+ = 20-40) located in the high buffer and low log-law layer for maximizing the overall performance. Furthermore, for the rib-array scheme, adequate inter-rib spacing is essential to achieve turbulence regeneration for enhancing near-wall heat transport.
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- author
- Zheng, Shao Fei ; Qiu, Yu Ping ; Zhang, Yi ; Gao, Shu Rong ; Yang, Yan Ru ; Li, Hai Wang ; Sunden, Bengt LU and Wang, Xiao Dong
- organization
- publishing date
- 2024-02-01
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physics of Fluids
- volume
- 36
- issue
- 2
- article number
- 025172
- publisher
- American Institute of Physics (AIP)
- external identifiers
-
- scopus:85186363064
- ISSN
- 1070-6631
- DOI
- 10.1063/5.0186554
- language
- English
- LU publication?
- yes
- id
- 8df8df0b-bd85-4508-811d-1af313a03b22
- date added to LUP
- 2024-03-20 10:12:28
- date last changed
- 2024-03-20 10:13:32
@article{8df8df0b-bd85-4508-811d-1af313a03b22,
abstract = {{<p>Owing to the limited supply and pressure margin in the air system, a cooling technique providing efficient heat transfer with lower flow loss is highly desirable for gas turbine blades. Microscale ribs have promised to be a potential cooling candidate. In this work, large eddy simulations are implemented to reveal the scale effect of micro ribs on the near-wall turbulent transport in a cooling channel. Considering a mechanistic study and practical applications, both single-rib and rib-array arrangements are studied with a wide range of dimensionless viscous-scaled rib heights involving the entire boundary layer. The results indicate that the rib-induced destruction and regeneration of coherent structures are, respectively, responsible for the weakened momentum transport and enhanced heat transport in the near-wall region. Using tiny ribs, regenerated quasi-streamwise vortices are mainly located in the buffer layer. The resulting turbulence burst greatly enhances wall heat transfer while keeping a lower flow loss due to the weak form drag. Regenerated hairpin vortices using tall ribs are activated in the log-law layer and intensively interact with mainstream. Along with improved wall heat transfer, the significant form drag results in a remarkably high flow loss. Accordingly, heat transfer and flow loss show different dependencies on the rib height, which contributes to an optimum height interval of ribs (e<sup>+</sup> = 20-40) located in the high buffer and low log-law layer for maximizing the overall performance. Furthermore, for the rib-array scheme, adequate inter-rib spacing is essential to achieve turbulence regeneration for enhancing near-wall heat transport.</p>}},
author = {{Zheng, Shao Fei and Qiu, Yu Ping and Zhang, Yi and Gao, Shu Rong and Yang, Yan Ru and Li, Hai Wang and Sunden, Bengt and Wang, Xiao Dong}},
issn = {{1070-6631}},
language = {{eng}},
month = {{02}},
number = {{2}},
publisher = {{American Institute of Physics (AIP)}},
series = {{Physics of Fluids}},
title = {{Scale effect of micro ribs on the turbulent transport in an internal cooling channel}},
url = {{http://dx.doi.org/10.1063/5.0186554}},
doi = {{10.1063/5.0186554}},
volume = {{36}},
year = {{2024}},
}