Open Access

ARTICLE

Effect of Surface Roughness on Flow Behavior and Conjugate Heat Transfer between TBC and Cooling Film

Yuzhang Wang^1,2,*, Zhuning Liu¹, Haozhe Sun¹, Zhuo Li³, Kanru Cheng¹, Chaoran Yang¹
1 School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Rd., Shanghai, China
2 Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, 800 Dong Chuan Rd., Shanghai, China
3 State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, China
* Corresponding Author: Yuzhang Wang. Email:
(This article belongs to the Special Issue: Heat and Mass Transfer in Aero-Engines and Gas Turbines)

Frontiers in Heat and Mass Transfer https://doi.org/10.32604/fhmt.2026.084530

Received 24 April 2026; Accepted 30 June 2026; Published online 13 August 2026

Abstract

During the operation of a gas turbine, the surface morphology of thermal barrier coatings (TBCs) of the high temperature blades inevitably evolves due to sintering, particle deposition or other factors, leading to an increase in surface roughness. This altered roughness can significantly influence the flow behavior of cooling films and the heat transfer performance of the coupled cooling film-TBC system. In this work, the flow behavior and conjugate heat transfer between cooling film and TBC under varying surface roughness conditions were investigated using the double distribution function lattice Boltzmann method (DDF-LBM) coupled with large eddy simulation (LES). The effects of surface roughness on the vortex structures, mean velocity profile, surface shear stress distribution, mean shear stress, surface temperature distribution, field synergy distribution, and mean heat transfer coefficient were analyzed. The results demonstrate that increased TBC surface roughness substantially enhances flow mixing, as evidenced by more widespread vortex distributions (identified by Ω criterion), modifications to the mean velocity profile, and increases in both the displacement and momentum thicknesses of the boundary layer. Moreover, surfaces with greater roughness exhibit more pronounced non-uniformities in shear stress and temperature distributions, which may induce cracking due to uneven mechanical loads and thermal stresses, thereby accelerating TBC degradation. The mean dimensionless surface temperature of the TBC increases by approximately 130%. Additionally, surface roughness augments heat transfer performance, with the convective heat transfer coefficient rising by up to 19.12%, and this phenomenon can be explained by the gradually saturated Field synergy distribution.

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Keywords

Thermal barrier coating; film cooling; surface roughness; double distribution function lattice Boltzmann method; large eddy simulation

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