Research Papers

Manufacturing Influences on Pressure Losses of Channel Fed Holes

[+] Author and Article Information
Karen A. Thole

Department of Mechanical
and Nuclear Engineering,
The Pennsylvania State University,
University Park, PA 16802

Vaidyanathan Krishnan

Corporate Technology,
Chennai, Tamilnadu 600113,India

Evan Landrum

Siemens Energy, Inc.,
Orlando, FL 32817

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 11, 2013; final manuscript received July 15, 2013; published online September 27, 2013. Editor: Ronald Bunker.

J. Turbomach 136(5), 051012 (Sep 27, 2013) (10 pages) Paper No: TURBO-13-1150; doi: 10.1115/1.4025226 History: Received July 11, 2013; Revised July 15, 2013

Variations from manufacturing can influence the overall pressure drop and subsequent flow rates through supply holes in such applications as film-cooling, transpiration cooling, and impingement cooling that are supplied by microchannels, pipe-flow systems, or secondary air systems. The inability to accurately predict flow rates has profound effects on engine operations. The objective of this study was to investigate the influence of several relevant manufacturing features that might occur for a cooling supply hole being fed by a range of channel configurations. The manufacturing variances included the ratio of the hole diameter to the channel width, the number of channel feeds (segments), the effect of hole overlap with respect to the channel sidewalls, and the channel Reynolds number. The results showed that the friction factors for the typically long channels in this study were independent of the tested inlet and exit hole configurations. The results also showed that the nondimensional pressure loss coefficients for the flow passing through the channel inlet holes and through the channel exit holes were found to be independent of the channel flow Reynolds number over the tested range. The geometric scaling ratio of the hole cross-sectional area to the channel cross-sectional area collapsed the pressure loss coefficients the best for both one and two flow segments for both the channel inlet and channel exit hole.

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Fig. 1

Schematic of the test stand used to study the internal cooling channels

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Fig. 2

Schematic of an example cooling channel showing the geometric parameters

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Fig. 3

Schematic cross-sectional views showing the three channel configurations that were tested

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Fig. 4

Plan view drawings (to scale) of the channel inlet and exit holes for example case E

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Fig. 5

Static pressure tap locations in wall layer 1 for a single flow segment (Case B)

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Fig. 6

Photos showing the static pressure taps installed in the primary wall (plenum top wall) for the benchmark test channel

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Fig. 7

Graph of the measured pressure drop from the plenum to the local channel tap for the benchmark geometry at several Reynolds numbers

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Fig. 8

Channel friction factors for the benchmark test (case B, 1 segment)

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Fig. 9

Pressure loss coefficients for the channel inlet and exit holes versus the channel Reynolds number (case B, 1 segment)

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Fig. 10

Example computational domain and mesh used for Case B with 1 flow segment

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Fig. 11

Plot of the channel friction factor for all test channel geometries in Table 1

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Fig. 12

Comparisons of the channel friction factor between the experiments and CFD predictions

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Fig. 13

Inlet hole loss coefficients for various scaling parameters (cases A–E)

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Fig. 14

The CFD contours of loss coefficient K within the symmetry plane for the inlet hole showing that the loss is dominant within the hole for case A versus within the channel for case E (ReDH=30,000)

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Fig. 15

Inlet hole loss coefficients using Kmin

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Fig. 16

Exit hole loss coefficients for various scaling parameters (cases A–E)

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Fig. 17

The CFD contours of loss coefficient K within the symmetry plane for the exit hole showing that the loss is dominant within the hole for both cases A and E (ReDH = 30,000)



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