Entrance effects on diffused film-cooling holes

A. Kohli, Karen Ann Thole

Research output: Contribution to journalConference article

17 Citations (Scopus)

Abstract

Film-cooling is a widely used method of prolonging blade life in high performance gas turbines and is implemented by injecting cold air through discrete holes on the blade surface. Most experimental research on film-cooling has been performed using round holes supplied by a stagnant plenum. This can be quite different from the actual turbine blade conditions in that a crossflow may be present whereby the internal channel Reynolds number could be as high as 90,000. This computational study uses a film-cooling hole that is inclined at 35° with respect to the mainstream and is diffused at the hole exit by 15°. An engine representative jet-to-mainstream density ratio of two was simulated. The test matrix consisted of fourteen different cases that were simulated for the two different blowing ratios in which the following effects were investigated: a) the effect of the orientation of the coolant supply channel relative to the cooling hole, b) the effect of the channel Reynolds number, and c) the effect of the metering length of the cooling hole. Results showed that the orientation of the coolant supply had a large effect whereby the worst orientation, in terms of a reduced adiabatic effectiveness, was predicted when the channel supplying the cooling hole was perpendicular to the mainstream. For this particular orientation, higher laterally averaged effectiveness occurred at lower channel Reynolds numbers and with the hole having a short metering length.

Original languageEnglish (US)
JournalAmerican Society of Mechanical Engineers (Paper)
Issue numberGT
StatePublished - Jan 1 1998
EventProceedings of the 1998 International Gas Turbine & Aeroengine Congress & Exhibition - Stockholm, Sweden
Duration: Jun 2 1998Jun 5 1998

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Cooling
Reynolds number
Coolants
Turbomachine blades
Jet engines
Blow molding
Gas turbines
Turbines
Air

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Cite this

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Entrance effects on diffused film-cooling holes. / Kohli, A.; Thole, Karen Ann.

In: American Society of Mechanical Engineers (Paper), No. GT, 01.01.1998.

Research output: Contribution to journalConference article

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AU - Thole, Karen Ann

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AB - Film-cooling is a widely used method of prolonging blade life in high performance gas turbines and is implemented by injecting cold air through discrete holes on the blade surface. Most experimental research on film-cooling has been performed using round holes supplied by a stagnant plenum. This can be quite different from the actual turbine blade conditions in that a crossflow may be present whereby the internal channel Reynolds number could be as high as 90,000. This computational study uses a film-cooling hole that is inclined at 35° with respect to the mainstream and is diffused at the hole exit by 15°. An engine representative jet-to-mainstream density ratio of two was simulated. The test matrix consisted of fourteen different cases that were simulated for the two different blowing ratios in which the following effects were investigated: a) the effect of the orientation of the coolant supply channel relative to the cooling hole, b) the effect of the channel Reynolds number, and c) the effect of the metering length of the cooling hole. Results showed that the orientation of the coolant supply had a large effect whereby the worst orientation, in terms of a reduced adiabatic effectiveness, was predicted when the channel supplying the cooling hole was perpendicular to the mainstream. For this particular orientation, higher laterally averaged effectiveness occurred at lower channel Reynolds numbers and with the hole having a short metering length.

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