Research Papers

Investigation of Sand Blocking Within Impingement and Film-Cooling Holes

[+] Author and Article Information
N. D. Cardwell

Department of Mechanical Engineering, Virginia Polytechnic Institute, Blacksburg, VA 24061

K. A. Thole

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

S. W. Burd

Pratt & Whitney, United Technologies Corporation, East Hartford, CT 06108

J. Turbomach 132(2), 021020 (Jan 21, 2010) (10 pages) doi:10.1115/1.3106702 History: Received February 01, 2009; Revised February 04, 2009; Published January 21, 2010; Online January 21, 2010

Gas turbines are not generally designed for operation with a particle laden inlet flow but, in fact, are commonly operated in unclean environments resulting in dirt, sand, and other debris ingestion. In addition to the negative effects within the main gas path, for aeroengines these particles are pulled into the coolant system where they can clog cooling passages and erode internal surfaces. Unlike previous research that focused on deposition and erosion within the main gas path, this study evaluated blocking in a double wall liner whereby both impingement and film-cooling holes were simulated. Double wall liners are commonly used in the combustor and turbine for combined internal and external cooling of metal components. Specifically, sand blockages were evaluated through comparisons of measured flowrates for a particular pressure ratio across the liner. Four liner geometries were tested whereby the coolant hole size and orientation were varied in test coupons. At ambient temperature, blocking was shown to be a function of the impingement flow area. A significant rise in blocking was observed as sand and metal temperatures were increased. The overlap between the impingement and film-cooling holes was also found to have a significant effect.

Copyright © 2010 by American Society of Mechanical Engineers
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Figure 1

Gas turbines operated in dust laden environments (1)

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Figure 2

Image of turbine nozzle guide vanes after ingestion of volcanic ash (3)

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Figure 3

Representative impingement and film-cooling double wall liner

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Figure 4

Overlap between impingement hole exit and film hole entrance (periodic section shown)

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Figure 5

Baseline flow parameter curves for all liners at ambient conditions and L1 at heated conditions

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Figure 6

Testing procedure for calculation of RFP

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Figure 7

Test facility used for studying sand blockages in the double wall liner coupons

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Figure 8

Size distributions for the test sand obtained by several methods

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Figure 9

Cumulative blocking effects versus slug flow for L1 at TM=982°C and Tc=649°C

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Figure 10

%RFP verses pressure ratio for all liners at ambient temperature

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Figure 11

Ambient temperature results plotted versus impingement flow area for all liners

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Figure 12

Post-test images of sand deposition patterns at ambient temperature for L1 at PR=1.03

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Figure 13

Effects of sand amount variation for L3 at ambient temperature

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Figure 14

Sand amounts for L1 and L3 at PR=1.06 at ambient temperature

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Figure 15

Comparison of all liners for ambient and heated tests at TM=982°C and Tc=649°C and two ranges of entering sand temperature at PR=1.03

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Figure 16

Upstream side of the L1 film-cooling plate at PR=1.03 for (a) ambient and (b) TM=982°C, Tc=649°C, and Ts=386°C

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Figure 17

Blockage associated with varied metals and entering sand temperatures for L1 at a fixed coolant temperature of Tc=649°C and PR=1.03

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Figure 18

Post-test images of elevated temperature sand deposition patterns for L1 at Tc=982°C, Tc=649°C, and PR=1.03 having two entering sand temperatures (a) Ts=386°C and (b) Ts=767°C




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