Cooling effectiveness for a shaped film cooling hole at a range of compound angles

Shane Haydt, Stephen P. Lynch

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

Shaped film cooling holes are a well-established cooling technique used in gas turbines to keep component metal temperatures in an acceptable range. One of the goals of film cooling is to reduce the driving temperature for convection at the wall, the success of which is generally represented by the film cooling adiabatic effectiveness. However, the introduction of a film cooling jet-in-crossflow, especially if it is oriented at a compound angle, can augment the convective heat transfer coefficient and dominate the flowfield. The present work aims to understand the effect that a compound angle has on the flowfield and adiabatic effectiveness of a shaped film cooling hole. Five orientations of the public 7-7-7 shaped film cooling hole were tested, from a streamwise oriented hole (0° compound angle) to a 60° compound angle hole, in increments of 15°. Additionally, two pitchwise spacings of P/D=3 and 6 were tested to examine the effect of hole-To-hole interaction. All cases were tested at a density ratio of 1.2 and blowing ratios ranging from 1.0 to 4.0. Experimental results show that increasing compound angle leads to increased lateral spread of coolant, and enables higher laterally-Averaged effectiveness at high blowing ratios. A smaller pitchwise spacing leads to more complete coverage of the endwall, and has higher laterally averaged effectiveness even when normalized by coverage ratio, suggesting that hole to hole interaction is important for compound angled holes. Steady RANS CFD was not able to capture the exact effectiveness levels, but did predict many of the observed trends. The lateral motion of the coolant jet was also quantified, both from the experimental data and the CFD prediction, and as expected, holes with a higher compound angle and higher blowing ratio have greater lateral motion, which generally also promotes holeto-hole interaction.

Original languageEnglish (US)
Title of host publicationHeat Transfer
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Print)9780791851104
DOIs
StatePublished - Jan 1 2018
EventASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018 - Oslo, Norway
Duration: Jun 11 2018Jun 15 2018

Publication series

NameProceedings of the ASME Turbo Expo
Volume5C-2018

Other

OtherASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018
CountryNorway
CityOslo
Period6/11/186/15/18

Fingerprint

Cooling
Blow molding
Coolants
Computational fluid dynamics
Heat transfer coefficients
Gas turbines
Temperature
Metals

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

Haydt, S., & Lynch, S. P. (2018). Cooling effectiveness for a shaped film cooling hole at a range of compound angles. In Heat Transfer (Proceedings of the ASME Turbo Expo; Vol. 5C-2018). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/GT2018-75726
Haydt, Shane ; Lynch, Stephen P. / Cooling effectiveness for a shaped film cooling hole at a range of compound angles. Heat Transfer. American Society of Mechanical Engineers (ASME), 2018. (Proceedings of the ASME Turbo Expo).
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abstract = "Shaped film cooling holes are a well-established cooling technique used in gas turbines to keep component metal temperatures in an acceptable range. One of the goals of film cooling is to reduce the driving temperature for convection at the wall, the success of which is generally represented by the film cooling adiabatic effectiveness. However, the introduction of a film cooling jet-in-crossflow, especially if it is oriented at a compound angle, can augment the convective heat transfer coefficient and dominate the flowfield. The present work aims to understand the effect that a compound angle has on the flowfield and adiabatic effectiveness of a shaped film cooling hole. Five orientations of the public 7-7-7 shaped film cooling hole were tested, from a streamwise oriented hole (0° compound angle) to a 60° compound angle hole, in increments of 15°. Additionally, two pitchwise spacings of P/D=3 and 6 were tested to examine the effect of hole-To-hole interaction. All cases were tested at a density ratio of 1.2 and blowing ratios ranging from 1.0 to 4.0. Experimental results show that increasing compound angle leads to increased lateral spread of coolant, and enables higher laterally-Averaged effectiveness at high blowing ratios. A smaller pitchwise spacing leads to more complete coverage of the endwall, and has higher laterally averaged effectiveness even when normalized by coverage ratio, suggesting that hole to hole interaction is important for compound angled holes. Steady RANS CFD was not able to capture the exact effectiveness levels, but did predict many of the observed trends. The lateral motion of the coolant jet was also quantified, both from the experimental data and the CFD prediction, and as expected, holes with a higher compound angle and higher blowing ratio have greater lateral motion, which generally also promotes holeto-hole interaction.",
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Haydt, S & Lynch, SP 2018, Cooling effectiveness for a shaped film cooling hole at a range of compound angles. in Heat Transfer. Proceedings of the ASME Turbo Expo, vol. 5C-2018, American Society of Mechanical Engineers (ASME), ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018, Oslo, Norway, 6/11/18. https://doi.org/10.1115/GT2018-75726

Cooling effectiveness for a shaped film cooling hole at a range of compound angles. / Haydt, Shane; Lynch, Stephen P.

Heat Transfer. American Society of Mechanical Engineers (ASME), 2018. (Proceedings of the ASME Turbo Expo; Vol. 5C-2018).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Haydt S, Lynch SP. Cooling effectiveness for a shaped film cooling hole at a range of compound angles. In Heat Transfer. American Society of Mechanical Engineers (ASME). 2018. (Proceedings of the ASME Turbo Expo). https://doi.org/10.1115/GT2018-75726