Research Papers

Heat Transfer Characteristics of an Oblique Jet Impingement Configuration in a Passage With Ribbed Surfaces

[+] Author and Article Information
Florian Hoefler1

Institute of Aerospace Thermodynamics (ITLR), Universität Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart, Germanyflorian.hoefler@itlr.uni-stuttgart.de

Simon Schueren, Jens von Wolfersdorf

Institute of Aerospace Thermodynamics (ITLR), Universität Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart, Germany

Shailendra Naik

 Alstom Power, Brown Boveri Strasse 7, CH-5401 Baden, Switzerland


Corresponding author.

J. Turbomach 134(3), 031022 (Jul 15, 2011) (9 pages) doi:10.1115/1.4003084 History: Received August 03, 2010; Revised August 20, 2010; Published July 15, 2011; Online July 15, 2011

Heat transfer measurements of a confined impingement cooling configuration with ribs on the target surfaces are presented. The assembly consists of four nonperpendicular walls of which one holds two rows of staggered inclined jets, each impinging on a different adjacent wall. The ribs are aligned with the inclined jet axes, have the same pitch, and are staggered to the impinging jets. The flow exhausts through two staggered rows of holes opposing the impingement wall. The passage geometry is related to a modern gas turbine blade cooling configuration. A transient liquid crystal technique was used to take spatially resolved surface heat transfer measurements for the ground area between the ribs. A comparison with the smooth baseline configuration reveals local differences and a generally reduced heat transfer for the rib-roughened case. Furthermore, lumped heat capacity measurements of the ribs yielded area averaged heat transfer information for the ribs. From the combination of ground and rib heat transfer measurements, it is concluded that the overall performance of the ribbed configuration depends on the Reynolds number. Of the five investigated jet Reynolds numbers from 10,000 to 75,000, only for the highest Re the averaged Nusselt numbers increase slightly compared with the smooth baseline configuration.

Copyright © 2012 by American Society of Mechanical Engineers
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Figure 2

Schematic of the experimental facility

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Figure 3

Schematic of test section geometry

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Figure 4

Schematic of staggered ribs arrangement

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Figure 1

Schematic of an impingement cooled midchord passage of a turbine blade

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Figure 14

Overall effectiveness as a function of Reynolds number

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Figure 5

Symmetric rib with insulated hub

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Figure 6

Local Nusselt numbers at Re=45,000

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Figure 7

CFD flow visualization

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Figure 8

Line averaged ground Nusselt numbers along s, Re=45,000

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Figure 9

Rib Nusselt number and contribution to overall heat flux as functions of Reynolds number

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Figure 10

Local Nusselt numbers, Re=45,000

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Figure 11

Line averaged rib side and segmental rib top Nusselt numbers along s, Re=45,000

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Figure 12

Dependence of Nusselt number ratio on Reynolds number for all passage walls

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Figure 13

Overall averaged Nusselt number as a function of Reynolds number



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