The effect of a meter-diffuser offset on shaped film cooling hole adiabatic effectiveness

Shane Haydt, Stephen Lynch, Scott Lewis

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

5 Scopus citations

Abstract

Shaped film cooling holes are used extensively in gas turbines to reduce component temperatures. These holes generally consist of a metering section through the material and a diffuser to spread coolant over the surface. These two hole features are created separately using electrical discharge machining, and occasionally an offset can occur between the meter and diffuser due to misalignment. The current study examines the potential impact of this manufacturing defect to the film cooling effectiveness for a well-characterized shaped hole known as the 7-7-7 hole. Five meter-diffuser offset directions and two offset sizes were examined, both computationally and experimentally. Adiabatic effectiveness measurements were obtained at a density ratio of 1.2 and blowing ratios ranging from 0.5 to 3. The detriment in cooling relative to the baseline 7-7-7 hole was worst when the diffuser was shifted upstream (aft meter-diffuser offset), and least when the diffuser was shifted downstream (fore meter-diffuser offset). At some blowing ratios and offset sizes, the fore meter-diffuser offset resulted in slightly higher adiabatic effectiveness than the baseline hole, due to a reduction in the high-momentum region of the coolant jet caused by a separation region created inside the hole by the fore meterdiffuser offset. Steady RANS predictions did not accurately capture the levels of adiabatic effectiveness or the trend in the offsets, but it did predict the fore offset's improved performance.

Original languageEnglish (US)
Title of host publicationHeat Transfer
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791849804
DOIs
StatePublished - Jan 1 2016
EventASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, GT 2016 - Seoul, Korea, Republic of
Duration: Jun 13 2016Jun 17 2016

Publication series

NameProceedings of the ASME Turbo Expo
Volume5C-2016

Other

OtherASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, GT 2016
CountryKorea, Republic of
CitySeoul
Period6/13/166/17/16

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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    Haydt, S., Lynch, S., & Lewis, S. (2016). The effect of a meter-diffuser offset on shaped film cooling hole adiabatic effectiveness. In Heat Transfer (Proceedings of the ASME Turbo Expo; Vol. 5C-2016). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/GT2016-56135