Effects of Reynolds number and turbulence intensity on endwall film cooling performance considering the variation of the upstream slot

The thermal protection of endwall structures relies critically on coolant injection through the clearance between first-stage turbine vanes and combustor outlets. To augment endwall film cooling effectiveness, this investigation initially improved conventional slot configurations. Following this enhancement, a comprehensive analysis was performed to evaluate how turbulence intensity, Reynolds numbers, and mass flow ratios (MFRs) affect cooling characteristics in both the reference configuration and the modified design (Case A). Through combined experimental measurements using pressure-sensitive paint (PSP) and computational simulations, Case A consistently demonstrated superior film cooling performance across multiple mass flow rates. Notably, at MFR = 1.0%, the cooling effectiveness of Case A exceeded the reference configuration by 19.13%. Under varying MFRs, peak cooling effectiveness occurred at Reynolds numbers of 1.2 × 10⁵ for the baseline geometry, whereas Case A achieved optimal performance at 1. 4 × 10⁵.Additionally, increasing turbulence intensity reduced average cooling effectiveness across endwall surfaces for both configurations. This inverse relationship remained consistent throughout all tested flow conditions.