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Research Papers

Scaling Sealing Effectiveness in a Stator–Rotor Cavity for Differing Blade Spans

[+] Author and Article Information
Reid A. Berdanier

Mem. ASME
Department of Mechanical Engineering,
The Pennsylvania State University,
University Park, PA 16802
e-mail: rberdanier@psu.edu

Iván Monge-Concepción, Brian F. Knisely

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

Michael D. Barringer, Karen A. Thole

Mem. ASME
Department of Mechanical Engineering,
The Pennsylvania State University,
University Park, PA 16802

Eric A. Grover

Pratt & Whitney,
East Hartford, CT 06118

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received December 7, 2018; final manuscript received December 24, 2018; published online January 21, 2019. Editor: Kenneth Hall.

J. Turbomach 141(5), 051007 (Jan 21, 2019) (10 pages) Paper No: TURBO-18-1350; doi: 10.1115/1.4042423 History: Received December 07, 2018; Revised December 24, 2018

As engine development continues to advance toward increased efficiency and reduced fuel consumption, efficient use of compressor bypass cooling flow becomes increasingly important. In particular, optimal use of compressor bypass flow yields an overall reduction of harmful emissions. Cooling flows used for cavity sealing between stages are critical to the engine and must be maintained to prevent damaging ingestion from the hot gas path. To assess cavity seals, the present study utilizes a one-stage turbine with true-scale engine hardware operated at engine-representative rotational Reynolds number and Mach number. Past experiments have made use of part-span (PS) rather than full-span (FS) blades to reduce flow rate requirements for the test rig; however, such decisions raise questions about potential influences of the blade span on sealing effectiveness measurements in the rim cavity. For this study, a tracer gas facilitates sealing effectiveness measurements in the rim cavity to compare data collected with FS engine airfoils and simplified, PS airfoils. The results from this study show sealing effectiveness does not scale as a function of relative purge flow with respect to main gas path flow rate when airfoil span is changed. However, scaling the sealing effectiveness for differing spans can be achieved if the fully purged flow rate is known. Results also suggest reductions of purge flow may have a relatively small loss of seal performance if the design is already near a fully purged condition. Rotor tip clearance is shown to have no effect on measured sealing effectiveness.

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References

Clark, K. , Barringer, M. , Johnson, D. , Thole, K. , Grover, E. , and Robak, C. , 2018, “ Effects of Purge Flow Configuration on Sealing Effectiveness in a Rotor-Stator Cavity,” ASME J. Eng. Gas Turbines Power, 140(11), p. 112502. [CrossRef]
Scobie, J. A. , Sangan, C. M. , Owen, J. M. , and Lock, G. D. , 2016, “ Review of Ingress in Gas Turbines,” ASME J. Eng. Gas Turbines Power, 138(12), p. 120801. [CrossRef]
Johnson, B. V. , Mack, G. J. , Paolillo, R. E. , and Daniels, W. A. , 1994, “ Turbine Rim Seal Gas Path Flow Ingestion Mechanisms,” AIAA Paper No. 94-2703.
Bayley, F. J. , and Owen, J. M. , 1970, “ The Fluid Dynamics of a Shrouded Disk System With a Radial Outflow of Coolant,” J. Eng. Power, 92(3), pp. 335–341. [CrossRef]
Phadke, U. P. , and Owen, J. M. , 1988, “ Aerodynamic Aspects of the Sealing of Gas Turbine Rotor-Stator Systems—Part 1: The Behavior of a Simple Shrouded Rotating-Disk Systems in a Quiescent Environment,” Int. J. Heat Fluid Flow, 9(2), pp. 98–105. [CrossRef]
Owen, J. M. , 2011, “ Prediction of Ingestion Through Turbine Rim Seals—Part I, Rotationally-Induced Ingress,” ASME J. Turbomach., 133(3), p. 031005. [CrossRef]
Owen, J. M. , 2011, “ Prediction of Ingestion Through Turbine Rim Seals—Part II: Externally-Induced and Combined Ingress,” ASME J. Turbomach., 133(3), p. 031006. [CrossRef]
Sangan, C. M. , Pountney, O. J. , Zhou, K. , Wilson, M. , Owen, J. M. , and Lock, G. D. , 2013, “ Experimental Measurements of Ingestion Through Turbine Rim Seals—Part I: Externally-Induced Ingress,” ASME J. Turbomach., 135(2), p. 021012. [CrossRef]
Sangan, C. M. , Pountney, O. J. , Zhou, K. , Wilson, M. , Owen, J. M. , and Lock, G. D. , 2013, “ Experimental Measurements of Ingestion Through Turbine Rim Seals—Part II: Rotationally-Induced Ingress,” ASME J. Turbomach., 135(2), p. 021013. [CrossRef]
Scobie, J. A. , Hualca, F. P. , Patinios, M. , Sangan, C. M. , Owen, J. M. , and Lock, G. D. , 2018, “ Re-Ingestion of Upstream Egress in a 1.5-Stage Gas Turbine Rig,” ASME J. Eng. Gas Turbines Power, 140(7), p. 072507. [CrossRef]
Barringer, M. , Coward, A. , Clark, K. , Thole, K. , Schmitz, J. , Wagner, J. , Alvin, M. A. , Burke, P. , and Dennis, R. , 2014, “ Development of a Steady Thermal Aero Research Turbine (START) for Studying Secondary Flow Leakages and Airfoil Heat Transfer,” ASME Paper No. GT2014-25570.
Clark, K. , Barringer, M. , Thole, K. , Clum, C. , Hiester, P. , Memory, C. , and Robak, C. , 2017, “ Effects of Purge Jet Momentum on Sealing Effectiveness,” ASME J. Eng. Gas Turbines Power, 139(3), p. 031904. [CrossRef]
Clark, K. , Barringer, M. , Thole, K. , Clum, C. , Hiester, P. , Memory, C. , and Robak, C. , 2016, “ Using a Tracer Gas to Quantify Sealing Effectiveness for Engine Realistic Rim Seals,” ASME Paper No. GT2016-58095.
Owen, J. M. , Zhou, K. , Pountney, O. J. , Wilson, M. , and Lock, G. , 2012, “ Prediction of Ingress Through Turbine Rim Seals—Part I: Externally Induced Ingress,” ASME J. Turbomach., 134(3), p. 031012. [CrossRef]

Figures

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Fig. 1

START facility layout following infrastructure upgrades

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Fig. 2

Turbine flow path cross section

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Fig. 3

Test section instrumentation layout

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Fig. 4

Schematic of CO2 injection and sampling system

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Fig. 5

Radial profiles of test section inlet conditions: (a) normalized total pressure and (b) total temperature with and without heat addition

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Fig. 6

Normalized vane surface static pressure at 50% span

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Fig. 7

Normalized flow parameter curves from part-span and full-span configurations. All data collected with nonrotating turbine arrangement.

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Fig. 8

Sealing effectiveness comparison for FS and PS hardware

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Fig. 9

Nondimensional rim seal and cavity pressures across a range of purge flows for full-span and part-span geometries

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Fig. 10

Sealing effectiveness comparisons for two full-span blade tip clearance configurations

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Fig. 11

Sealing effectiveness as a function of pressure ratio across the purge holes

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Fig. 12

Empirical model for sealing effectiveness [14] compared with experimental data for rim seal (location A)

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Fig. 13

Empirical model for sealing effectiveness [14] compared with experimental data for outer rim cavity (location B)

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Fig. 14

Sealing effectiveness at inner radial locations as a function of net sealing flow rate

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Fig. 15

Nondimensional pressures for FS configuration identifying flow-driving pressure differentials

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Fig. 16

Nondimensional pressures for PS configuration identifying flow-driving pressure differentials

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Fig. 17

Schematic of secondary flow paths without TOBI flow: (a) blade cooling holes present (FS) and (b) blade cooling holes absent (PS)

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