Session: Student Poster Competition

Submission Number: 186780

Numerical Study of Film Cooling Performance and Flow Structures With Surface Roughness 

Gas turbines require high turbine inlet temperatures (TIT) to achieve high thermal efficiency. However, high TIT can cause thermal deformation and damage to turbine blades, and thus various cooling technologies have been investigated to protect blades from high TIT. Film cooling, one of many blade-cooling methods, injects coolant through film cooling holes to form a cooling layer that reduces direct contact between the hot gas and the blade surface, thereby protecting the surface from heat-induced damage. Various factors influencing film cooling have been explored to improve film cooling performance. Among them, surface roughness generated by the erosion and deposition of the working fluid affects film-cooling performance and alters flow characteristics. In this study, trigonometric roughness elements with prescribed height and width are applied to the mainstream surface, and the influence of the resulting surface roughness on film-cooling effectiveness and flow characteristics is evaluated through numerical analysis. A coolant jet typically has low momentum, and it tends to remain attached to the wall at a low blowing ratio. On the other hand, a rough surface intensifies mixing between the mainstream and the coolant, thereby promoting coolant dilution and reducing film cooling effectiveness relative to a smooth surface. When the blowing ratio is higher with a smooth surface, the increased coolant-jet momentum causes the jet to blow off from the surface, detach from the wall, and penetrate into the mainstream. Consequently, cooling-layer formation is suppressed, and film-cooling performance is reduced compared with the low-blowing-ratio case. However, the rough surface mitigates coolant-jet blow-off at high blowing ratios by generating stronger turbulent mixing, which promotes lateral spreading of the cooling layer and leads to higher film cooling performance than that of the flat plate.

This work was partly supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (RS-2025-00557360), and by BK21 FOUR Program by Jeonbuk National University Research Grant.

Presenting Author: Taehyeon Kim Jeonbuk National University

Presenting Author Biography: Taehyeon Kim is an M.S. student in the Department of Mechanical-Aerospace-Electric Convergence Engineering at Jeonbuk National University. His research interests include film cooling, heat transfer, and computational fluid dynamics (CFD).

Authors:

Taehyeon Kim Jeonbuk National University
Jisu Park Jeonbuk National University
Changwoo Kang Jeonbuk National University