Flowfield measurements for film-cooling holes with expanded exits

K. Thole, M. Gritsch, A. Schulz, S. Wittig

Research output: Contribution to journalArticle

181 Citations (Scopus)

Abstract

One viable option to improve cooling methods used for gas turbine blades is to optimize the geometry of the film-cooling hole. To optimize that geometry, effects of the hole geometry on the complex jet-in-crossflow interaction need to be understood. This paper presents a comparison of detailed flowfield measurements for three different single, scaled-up hole geometries, all at a blowing ratio and density ratio of unity. The hole geometries include a round hole, a hole with a laterally expanded exit, and a hole with a forward-laterally expanded exit. In addition to the flowfield measurements for expanded cooling hole geometries being unique to the literature, the testing facility used for these measurements was also unique in that both the external mainstream Much number (Maa ∞ = 0.25) and internal coolant supply Mach number (Mac = 0.3) were nearly matched. Results show that by expanding the exit of the cooling holes, both the penetration of the cooling jet and the intense shear regions are significantly reduced relative to a round hole. Although the peak turbulence level for all three hole geometries was nominally the same, the source of that turbulence was different. The peak turbulence level for both expanded holes was located at the exit of the cooling hole resulting from the expansion angle being too large. The peak turbulence level for the round hole was located downstream of the hole exit where the velocity gradients were very large.

Original languageEnglish (US)
Pages (from-to)327-336
Number of pages10
JournalJournal of Turbomachinery
Volume120
Issue number2
DOIs
StatePublished - Apr 1998

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Cooling
Geometry
Turbulence
Blow molding
Coolants
Mach number
Turbomachine blades
Gas turbines
Testing

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Cite this

Thole, K. ; Gritsch, M. ; Schulz, A. ; Wittig, S. / Flowfield measurements for film-cooling holes with expanded exits. In: Journal of Turbomachinery. 1998 ; Vol. 120, No. 2. pp. 327-336.
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Flowfield measurements for film-cooling holes with expanded exits. / Thole, K.; Gritsch, M.; Schulz, A.; Wittig, S.

In: Journal of Turbomachinery, Vol. 120, No. 2, 04.1998, p. 327-336.

Research output: Contribution to journalArticle

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