Experimental Study on the Improvement of Film Cooling Effectiveness of Various Modified Configurations Based on a Fan-Shaped Film Cooling Hole on an Endwall

Seokmin Kim, DongEun Lee, Young Seok Kang and Dong-Ho Rhee ()
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Seokmin Kim: Aerospace System Engineering, University of Science and Technology, Gajeong-Ro 217, Yuseong-Gu, Daejeon 34113, Republic of Korea
DongEun Lee: Aerospace System Engineering, University of Science and Technology, Gajeong-Ro 217, Yuseong-Gu, Daejeon 34113, Republic of Korea
Young Seok Kang: Aeropropulsion Research Division, Korea Aerospace Research Institute, Gwahak-Ro 169-84, Yuseong-Gu, Daejeon 34133, Republic of Korea
Dong-Ho Rhee: Aeropropulsion Research Division, Korea Aerospace Research Institute, Gwahak-Ro 169-84, Yuseong-Gu, Daejeon 34133, Republic of Korea

Energies, 2023, vol. 16, issue 23, 1-19

Abstract: Several studies have previously been conducted to improve the cooling performance of film cooling. However, most of the research has conducted experiments with film cooling holes on flat plates, and thus, the results of these studies do not encompass the influence of the complex mainstream behavior within the turbine passage on film cooling. In this study, three different film cooling hole configurations were installed on the endwall of a turbine linear cascade to measure adiabatic film cooling effectiveness and evaluate cooling performance. The film cooling holes compared in the experiment for film cooling effectiveness were a 7-7-7 fan-shaped hole (Baseline), a Baseline with a double-step structure at the hole exit (Staircase), and a Baseline with an additional expanded passage at the hole leading edge (Compound Expansion). A total of nine holes were manufactured on the turbine endwall to assess film cooling performance, as various factors, such as mainstream acceleration, secondary flow within the turbine passage, and so on, can influence film cooling. Adiabatic film cooling effectiveness was measured using the pressure-sensitive paint (PSP) technique. Mass flow ratios ranging from 0.25% to 1.25% of the mass flow rate of a single turbine passage were supplied to the plenum chamber within the test rig. As a result, all experimental results confirmed the impact of secondary flow within the turbine passage on film cooling. In the case of the Staircase, it exhibits an overall cooling trend similar to the Baseline. It shows small cooling performance degradation compared with Baseline due to lift-off, and its double-step structure laterally expanding results in better cooling performance at high mass flow ratio (MFR) conditions. For the Compound Expansion, at low MFR, the momentum of the coolant is lower compared with other configurations, leading to lower cooling performance due to the influence of secondary flow. However, at high MFR, the Compound Expansion provides wider protection compared with other hole geometries and shows high cooling performance.

Keywords: gas turbine; film cooling; linear turbine cascade; turbine endwall; fan-shaped film cooling hole; pressure-sensitive paint; staircase; compound expansion (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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