Convective heat transfer enhancement through additively built multiscale micro-tetrahedron features

Vanshika Singh; Fred List; Chase Joslin; Paul Brackmann; S. S. Babu; M. M. Kirka

doi:10.1016/j.icheatmasstransfer.2025.108888

Convective heat transfer enhancement through additively built multiscale micro-tetrahedron features

Vanshika Singh
, Fred List
, Chase Joslin
, Paul Brackmann
, S. S. Babu
, M. M. Kirka

Research output: Contribution to journal › Article › peer-review

Abstract

Use of Additive Manufacturing (AM) to improve the heat transfer characteristics of tip shrouds in high-pressure turbines is being considered by industries. Existing designs of these components integrate micro-cooling channels to reduce the bulk temperature for improved life. In this research, closely packed micro tetrahedron features in addition to AM roughness has been considered. This multiscale surface characteristics increased surface area per unit volume available for heat exchange. Micro-tet features were designed, manufactured, characterized, and evaluated systematically while increasing their height. An enormous increase in the overall wetted surface area by 200 % was measured. The convective heat transfer enhancement was ∼3.72 times EDM rough coupon, and friction factor enhancement was ∼5.5 times EDM rough coupon. Furthermore, the proposed design offers 2.5 times enhanced heat transfer for a given 2 W pumping power compared to our EDM rough coupon. Heat transfer enhancement was observed to not vary strongly with increased Reynolds number. Such complex designs are only possible through additive manufacturing for increased heat transfer with little pressure penalty. Finally, increasing the micro-tet height for increased surface area and improved heat exchange beyond an upper limit might not be a significant benefit as it gets compensated by increasing skin friction.

Original language	English
Article number	108888
Journal	International Communications in Heat and Mass Transfer
Volume	164
DOIs	https://doi.org/10.1016/j.icheatmasstransfer.2025.108888
State	Published - May 2025

Funding

This research is sponsored by the US Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), Advanced Materials and Manufacturing Technologies Office (AMMTO) under contract DE-AC05-00OR22725 with UT-Battelle LLC. The research was performed partiality at Oak Ridge National Laboratory's Manufacturing Demonstration Facility, an Office of Energy Efficiency and Renewable Energy user facility. Many thanks to Dr. Prashant Singh (Assistant Professor, Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville) for his valuable advice, inputs, and review during the process. This paper was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. This research is sponsored by the US Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), Advanced Materials and Manufacturing Technologies Office (AMMTO) under contract DE-AC05-00OR22725 with UT-Battelle LLC. The research was performed partiality at Oak Ridge National Laboratory's Manufacturing Demonstration Facility, an Office of Energy Efficiency and Renewable Energy user facility. Many thanks to Dr. Prashant Singh (Assistant Professor, Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville) for his valuable advice, inputs, and review during the process.

Keywords

Additive manufacturing
Friction factor
Gas turbine
Heat transfer
Micro - tetrahedron
Multi-scale surface characteristics

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10.1016/j.icheatmasstransfer.2025.108888

Cite this

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title = "Convective heat transfer enhancement through additively built multiscale micro-tetrahedron features",

abstract = "Use of Additive Manufacturing (AM) to improve the heat transfer characteristics of tip shrouds in high-pressure turbines is being considered by industries. Existing designs of these components integrate micro-cooling channels to reduce the bulk temperature for improved life. In this research, closely packed micro tetrahedron features in addition to AM roughness has been considered. This multiscale surface characteristics increased surface area per unit volume available for heat exchange. Micro-tet features were designed, manufactured, characterized, and evaluated systematically while increasing their height. An enormous increase in the overall wetted surface area by 200 \% was measured. The convective heat transfer enhancement was ∼3.72 times EDM rough coupon, and friction factor enhancement was ∼5.5 times EDM rough coupon. Furthermore, the proposed design offers 2.5 times enhanced heat transfer for a given 2 W pumping power compared to our EDM rough coupon. Heat transfer enhancement was observed to not vary strongly with increased Reynolds number. Such complex designs are only possible through additive manufacturing for increased heat transfer with little pressure penalty. Finally, increasing the micro-tet height for increased surface area and improved heat exchange beyond an upper limit might not be a significant benefit as it gets compensated by increasing skin friction.",

keywords = "Additive manufacturing, Friction factor, Gas turbine, Heat transfer, Micro - tetrahedron, Multi-scale surface characteristics",

author = "Vanshika Singh and Fred List and Chase Joslin and Paul Brackmann and Babu, \{S. S.\} and Kirka, \{M. M.\}",

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year = "2025",

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doi = "10.1016/j.icheatmasstransfer.2025.108888",

language = "English",

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AU - Singh, Vanshika

AU - List, Fred

AU - Joslin, Chase

AU - Brackmann, Paul

AU - Babu, S. S.

AU - Kirka, M. M.

PY - 2025/5

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N2 - Use of Additive Manufacturing (AM) to improve the heat transfer characteristics of tip shrouds in high-pressure turbines is being considered by industries. Existing designs of these components integrate micro-cooling channels to reduce the bulk temperature for improved life. In this research, closely packed micro tetrahedron features in addition to AM roughness has been considered. This multiscale surface characteristics increased surface area per unit volume available for heat exchange. Micro-tet features were designed, manufactured, characterized, and evaluated systematically while increasing their height. An enormous increase in the overall wetted surface area by 200 % was measured. The convective heat transfer enhancement was ∼3.72 times EDM rough coupon, and friction factor enhancement was ∼5.5 times EDM rough coupon. Furthermore, the proposed design offers 2.5 times enhanced heat transfer for a given 2 W pumping power compared to our EDM rough coupon. Heat transfer enhancement was observed to not vary strongly with increased Reynolds number. Such complex designs are only possible through additive manufacturing for increased heat transfer with little pressure penalty. Finally, increasing the micro-tet height for increased surface area and improved heat exchange beyond an upper limit might not be a significant benefit as it gets compensated by increasing skin friction.

AB - Use of Additive Manufacturing (AM) to improve the heat transfer characteristics of tip shrouds in high-pressure turbines is being considered by industries. Existing designs of these components integrate micro-cooling channels to reduce the bulk temperature for improved life. In this research, closely packed micro tetrahedron features in addition to AM roughness has been considered. This multiscale surface characteristics increased surface area per unit volume available for heat exchange. Micro-tet features were designed, manufactured, characterized, and evaluated systematically while increasing their height. An enormous increase in the overall wetted surface area by 200 % was measured. The convective heat transfer enhancement was ∼3.72 times EDM rough coupon, and friction factor enhancement was ∼5.5 times EDM rough coupon. Furthermore, the proposed design offers 2.5 times enhanced heat transfer for a given 2 W pumping power compared to our EDM rough coupon. Heat transfer enhancement was observed to not vary strongly with increased Reynolds number. Such complex designs are only possible through additive manufacturing for increased heat transfer with little pressure penalty. Finally, increasing the micro-tet height for increased surface area and improved heat exchange beyond an upper limit might not be a significant benefit as it gets compensated by increasing skin friction.

KW - Additive manufacturing

KW - Friction factor

KW - Gas turbine

KW - Heat transfer

KW - Micro - tetrahedron

KW - Multi-scale surface characteristics

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U2 - 10.1016/j.icheatmasstransfer.2025.108888

DO - 10.1016/j.icheatmasstransfer.2025.108888

M3 - Article

AN - SCOPUS:105000531843

SN - 0735-1933

VL - 164

JO - International Communications in Heat and Mass Transfer

JF - International Communications in Heat and Mass Transfer

M1 - 108888

ER -

Convective heat transfer enhancement through additively built multiscale micro-tetrahedron features

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