This paper presents a numerical investigation of double-hole (DH) film cooling on the suction surface of a C3X turbine blade, with single-hole (SH) configurations used as reference cases for comparison. Reynolds-Averaged Navier–Stokes (RANS) simulations are performed using the realizable k–ε turbulence model with enhanced near-wall treatment and a refined mesh (y+ < 5). The study considers four blowing ratios (MR = 0.5, 0.7, 1.0, and 1.4) under low and high freestream turbulence intensities (0.02% and 12%), representative of turbine operating conditions. Film-cooling performance is evaluated using temperature fields, effectiveness distributions, and flow visualizations. The results show that DH configurations consistently improve film-cooling performance compared to SH cases, particularly at moderate blowing ratios and elevated turbulence levels. The enhancement is reflected in improved surface coverage and more stable downstream cooling behavior. Overall, the findings indicate that the effectiveness of double-hole injection is strongly dependent on operating conditions, with the most favorable performance observed at moderate-to-high blowing ratios under high turbulence intensity. The results provide design-oriented insight into optimizing hole multiplicity for improved thermal protection and operational robustness in turbine blade cooling applications.
MargasonRJ. Fifty years of jet in crossflow research. In: Proceedings of the AGARD Symposium on Computational and Experimental Assessment of Jets in Crossflow, AGARD-CP-534. Advisory Group for Aerospace Research and Development, 1993, pp. 1.1–1.41.
2.
BoyceMP. Gas turbine engineering handbook. 2nd ed.Elsevier, 2002.
3.
SinhaAKBogardDGCrawfordME. Film cooling effectiveness downstream of a single row of holes with variable density ratio. J Turbomach1991; 113(3): 442–449. https://doi.org/10.1115/1.2927894
4.
EkkadSVOuSRivirRB. A transient infrared thermography method for simultaneous film cooling effectiveness and heat transfer coefficient measurements from a single test. J Turbomach2004; 126(4): 597–603. https://doi.org/10.1115/1.1791283
JohnsonBTianWZhangK, et al.Experimental study of density ratio effects on film cooling injection from discrete holes using PIV and PSP techniques. Int J Heat Mass Tran2014; 76: 337–349. https://doi.org/10.1016/j.ijheatmasstransfer.2014.04.028
7.
ZhengKTianWQinJ, et al.Experimental study on film cooling performance improvement using an upstream micro-vortex generator. Exp Therm Fluid Sci2021; 127: 110410. https://doi.org/10.1016/j.expthermflusci.2021.110410
JohnsonPLShyamVHahC. Reynolds-averaged Navier–Stokes solutions to flat plate film cooling scenarios. NASA Technical Memorandum, NASA/TM–2011-217025. 2011.
10.
YuZLiCAnB, et al.Experimental investigation of film cooling effectiveness on a gas turbine blade pressure surface with diffusion slot holes. Appl Therm Eng2020; 168: 114851. https://doi.org/10.1016/j.applthermaleng.2019.114851
11.
LiuCZhangFZhangS, et al.Experimental investigation of full-coverage film cooling effectiveness of a turbine blade with shaped holes. Chin J Aeronaut2022; 35(3): 297–308. https://doi.org/10.1016/j.cja.2021.06.022
12.
SaumweberCSchulzAWittigS. Free-stream turbulence effects on film cooling with shaped holes. J Turbomach2003; 125(1): 65–73. https://doi.org/10.1115/1.1515336
13.
WilliamsRPDysonTEBogardDG, et al.Sensitivity of overall effectiveness to film cooling and internal cooling on a turbine vane suction side. J Turbomach2014; 136(3): 031006. https://doi.org/10.1115/1.4024681
TaheriYRajabi ZargarabadiMJahromiM. Experimental and numerical study on effects of shaped multi-holes on film cooling effectiveness. J Therm Anal Calorimetry2020; 146: 1723–1733. https://doi.org/10.1007/s10973-020-10157-4
16.
FunazakiKKawabataHOkitaY. Free-stream turbulence effects on leading-edge film cooling. Int J Gas Turbine Propuls Power Syst2012; 4(1): 43–50. https://doi.org/10.38036/jgpp.4.1_43
17.
HuangKChengXYangX, et al.Experimental and numerical investigation of film cooling on a turbine vane pressure side with various internal rib angles. Appl Therm Eng2024; 239: 122100. https://doi.org/10.1016/j.applthermaleng.2023.122100
18.
AmesFE. Experimental study of vane heat transfer and film cooling at elevated turbulence levels. NASA Contractor Report, NASA CR-198525. Washington, DC: National Aeronautics and Space Administration (NASA).1996.
19.
LiuRLiHLinJ, et al.Experimental and numerical investigation of film cooling effectiveness on a gas turbine blade tip region. Int J Therm Sci2022; 177: 107544. https://doi.org/10.1016/j.ijthermalsci.2022.107544
20.
LiBLiuCYeL, et al.Evaluation of film cooling effect in multi-row hole configurations on turbine blade leading edge. Energy2024; 309: 132908. https://doi.org/10.1016/j.energy.2024.132908
BaghernejadAHatamiMAslanzadehE. Numerical study of film cooling effectiveness of a gas turbine blade under variable blowing ratio and turbulence intensity. Heat Transfer2023; 52: 1048–1075. https://doi.org/10.1002/htj.22729
27.
LiSPengTLiuL, et al. Numerical Simulation of Turbine Blade Film-cooling with Different Blowing Ratio and Hole-to-hole Space. In: CenK.ChiY.WangF. (eds) Challenges of Power Engineering and Environment. Berlin, Heidelberg: Springer, 2017. https://doi.org/10.1007/978-3-540-76694-0_258
BaheriSJubranBAAlavi TabriziSP. Effect of turbulence intensity on film cooling of gas turbine blade from trenched shaped holes. Heat Mass Tran2011; 48(5): 831–840.
YanYDongYGuoW. High-pressure turbine rotor blade end-wall flow and cooling characteristics: trends and perspectives. Proc Inst Mech Eng A J Power Energy2025; 239(4). https://doi.org/10.1177/095765092513312
32.
HalderN. Experimental and numerical study of film cooling enhancement using vortex generators. Proc Inst Mech Eng A J Power Energy2024; 238(6): 999–1018. https://doi.org/10.1177/09576509241248678
33.
ChengXMaYTaoWQ, et al. Experimental investigation on the effect of internal rib turbulators on film cooling effectiveness with coolant cross-flow. Proc Inst Mech Eng A J Power Energy. 2025; 239(5): 803–816. https://doi.org/10.1177/09576509251317561
34.
ZhangZHuTSuX, et al.Optimization of the double-expansion film-cooling hole using CFD. Entropy2023; 25(3): 410. https://doi.org/10.3390/e25030410
35.
HangJZhangJWangC, et al.Numerical investigation of single-row double-jet film cooling of a turbine guide vane under high-temperature and high-pressure conditions. Energies2022; 15(1): 287. https://doi.org/10.3390/en15010287
36.
AminnuddinHFAbdullahK. Numerical investigation on pitch distance, compound angle and turbulence intensity of double cylindrical film cooling holes. ARPN J Eng Appl Sci2017; 12(8): 1–10.
37.
WaltersDKLeylekJH. Detailed analysis of film-cooling physics: part I—streamwise injection with cylindrical holes. J Turbomach2000; 122(1): 102–112. https://doi.org/10.1115/1.555433
