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TECHNICAL PAPERS

End-Wall Film Cooling Through Fan-Shaped Holes With Different Area Ratios

[+] Author and Article Information
Giovanna Barigozzi

Dipartimento di Ingegneria Industriale, Università degli Studi di Bergamo, Viale Marconi, 24044 Dalmine (BG) Italygiovanna.barigozzi@unibg.it

Giuseppe Franchini

Dipartimento di Ingegneria Industriale, Università degli Studi di Bergamo, Viale Marconi, 24044 Dalmine (BG) Italy

Antonio Perdichizzi

Dipartimento di Ingegneria Industriale, Università degli Studi di Bergamo, Viale Marconi, 24044 Dalmine (BG) Italyantonio.perdichizzi@unibg.it

J. Turbomach 129(2), 212-220 (Jul 21, 2006) (9 pages) doi:10.1115/1.2464140 History: Received July 12, 2006; Revised July 21, 2006

The present paper reports on the aerothermal performance of a nozzle vane cascade, with film-cooled end walls. The coolant is injected through four rows of cylindrical holes with conical expanded exits. Two end-wall geometries with different area ratios have been compared. Tests have been carried out at low speed (M=0.2), with coolant to mainstream mass flow ratio varied in the range 0.5–2.5%. Secondary flow assessment has been performed through three-dimensional (3D) aerodynamic measurements, by means of a miniaturized five-hole probe. Adiabatic effectiveness distributions have been determined by using the wide-band thermochromic liquid crystals technique. For both configurations and for all the blowing conditions, the coolant share among the four rows has been determined. The aerothermal performances of the cooled vane have been analyzed on the basis of secondary flow effects and laterally averaged effectiveness distributions; this analysis was carried out for different coolant mass flow ratios. It was found that the smaller area ratio provides better results in terms of 3D losses and secondary flow effects; the reason is that the higher momentum of the coolant flow is going to better reduce the secondary flow development. The increase of the fan-shaped hole area ratio gives rise to a better coolant lateral spreading, but appreciable improvements of the adiabatic effectiveness were detected only in some regions and for large injection rates.

Copyright © 2007 by American Society of Mechanical Engineers
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Figures

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Figure 4

Cd values for the different cooling schemes

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Figure 5

Mass flow sharing among rows versus MFR

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Figure 6

CONF3 local BR values for variable MFR

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Figure 7

Secondary kinetic energy loss coefficient (primary), vorticity and velocity vectors: MFR=0.5%: (a) CONF2, (b) CONF3

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Figure 8

Secondary kinetic energy loss coefficient (primary), vorticity and velocity vectors: MFR=1.5%: (a) CONF2, (b) CONF3

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Figure 9

Secondary kinetic energy loss coefficient (primary), vorticity, and velocity vectors: MFR=2.5%: (a) CONF2 and (b) CONF3

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Figure 15

Axial- and pitch-averaged adiabatic effectiveness distributions versus MFR

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Figure 1

Cascade and end-wall cooling geometry: (a) CONF2 and (b) CONF3

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Figure 2

Detail of hole geometry: (a) CONF2 and (b) CONF3

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Figure 10

Spanwise flow angle deviation: (a) MFR=0.5% and (b) MFR=2.5%

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Figure 11

Mass-averaged primary and thermodynamic secondary energy loss coefficients versus MFR

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Figure 12

η distributions for selected MFR values: (a) CONF2 and (b) CONF3

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Figure 13

Pitchwise η distribution downstream of row A: MFR=1%, X∕cax=2%

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Figure 14

Pitch-averaged adiabatic effectiveness distributions at different MFR: (a) CONF2 and (b) CONF3

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