Flowfield measurements for film-cooling holes with expanded exits

Journal Article · Wed Apr 01 04:00:00 EST 1998 · Journal of Turbomachinery

DOI:https://doi.org/10.1115/1.2841410· OSTI ID:290080

Thole, K; Gritsch, M; Schulz, A; Wittig, S ^[1]

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1. Univ. Karlsruhe (Germany). Inst. fuer Thermische Stroemungsmaschinen

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 Mach number (Ma{sub {infinity}} = 0.25) and internal coolant supply Mach number (Ma{sub c} = 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.

• Sponsoring Organization: USDOE
• OSTI ID: 290080
• Report Number(s): CONF-960608--
• Journal Information: Journal of Turbomachinery, Journal Name: Journal of Turbomachinery Journal Issue: 2 Vol. 120; ISSN JOTUEI; ISSN 0889-504X
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
AIR FLOW
ENERGY EFFICIENCY
FILM COOLING
TURBINE BLADES
TURBULENT FLOW