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Research Papers: Gas Turbines: Structures and Dynamics

Flow Resistance Coefficients of Porous Brush Seal as a Function of Pressure Load

[+] Author and Article Information
Yahya Doğu

Mechanical Engineering Department,
Kirikkale University,
Yahsihan 71450, Kirikkale, Turkey
e-mail: yahya.dogu@hotmail.com

Mustafa C. Sertçakan

TUSAS Engine Industries, Inc. (TEI),
Eskisehir 26003, Turkey
e-mail: mustafacem.sertcakan@tei.com.tr

Koray Gezer

Mechanical Engineering Department,
Kirikkale University,
Yahsihan 71450, Kirikkale, Turkey
e-mail: koraygezer90@gmail.com

Mustafa Kocagül

TUSAS Engine Industries, Inc. (TEI),
Eskisehir 26003, Turkey
e-mail: mustafa.kocagul@tei.com.tr

1Corresponding author.

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received November 29, 2017; final manuscript received December 21, 2017; published online April 25, 2018. Editor: David Wisler.

J. Eng. Gas Turbines Power 140(8), 082504 (Apr 25, 2018) (8 pages) Paper No: GTP-17-1635; doi: 10.1115/1.4038994 History: Received November 29, 2017; Revised December 21, 2017

Developments in brush seal analyses tools have been covering advanced flow and structural analyses since brush seals are applied at elevated pressure loads, temperatures, surface speeds, and transients. Brush seals have dynamic flow and structural behaviors that need to be investigated in detail in order to estimate final leakage output and service life. Bristles move, bend, and form a grift matrix depending on pressure load. The level of pressure load determines the tightness of the bristle pack, and thus, the leakage. In the computational fluid dynamics (CFD) analyses of this work, the bristle pack is treated as a porous medium. Based on brush seal test data, the flow resistance coefficients (FRC) for the porous bristle pack are calibrated as a function of pressure load. A circular seal is tested in a static test rig under various pressure loads at room temperature. The FRC calibration is based on test leakage and literature-based axial pressure distribution on the rotor surface and radial pressure distribution over the backing plate. The anisotropic FRC are treated as spatial dependent in axisymmetrical coordinates. The fence height region and the upper region of bristle pack have different FRC since the upper region is supported by backing plate, while bristles are free to move and bend at the fence height region. The FRC are found to be almost linearly dependent on the pressure load for investigated conditions. The blow-down is also calculated by incorporating test leakage and calibrated FRC.

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References

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Figures

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Fig. 4

Brush seal static leakage test cell

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Fig. 3

Brush seal FRC parameters and calibration schematics

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Fig. 2

Bristle distribution in the pack

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Fig. 1

Brush seal schematics

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Fig. 5

Brush seal CFD model domain and boundary conditions

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Fig. 14

Blow-down versus initial clearance

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Fig. 10

Comparison of analysis and test results with the literature: (a) normalized leakage versus pressure load and (b) effective clearance versus pressure load

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Fig. 8

Velocity vectors normalized with Mach number

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Fig. 9

Mach number contours

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Fig. 13

FRC* versus pressure load

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Fig. 11

Axial pressure distribution on rotor surface

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Fig. 12

Radial pressure distribution over backing plate

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