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Research Papers: Gas Turbines: Structures and Dynamics

Brush Seal Structural Analysis and Correlation With Tests for Turbine Conditions

[+] Author and Article Information
E. Tolga Duran

SDM R&D,
Istanbul 34906, Turkey
e-mail: t.duran@sdmresearch.com

Mahmut F. Aksit

Mechatronics,
Sabanci University,
Istanbul 34956, Turkey
e-mail: aksit@sabanciuniv.edu

Murat Ozmusul

SDM R&D,
Istanbul 34906, Turkey
e-mail: m.ozmusul@sdmresearch.com

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 14, 2015; final manuscript received September 1, 2015; published online November 3, 2015. Editor: David Wisler.

J. Eng. Gas Turbines Power 138(5), 052502 (Nov 03, 2015) (13 pages) Paper No: GTP-15-1292; doi: 10.1115/1.4031565 History: Received July 14, 2015; Revised September 01, 2015

Bristle tip contact forces and resulting stress levels under engine conditions are critical for optimizing brush seal performance as well as for achieving operational safety. Literature survey reveals the lack of test data and analysis methods for evaluating seal stiffness and stress levels under operating conditions. In an attempt to meet this need, a custom test rig design and methodology have been developed to perform stiffness tests under pressure and rotor speed of 3000 rpm. Finite element (FE) simulations have been performed for brush seals and results have been correlated with the test data of this study. Considering the critical importance of contact loads on brush seal overall performance and system health, and due to the complicated structure of brush seals, where bristles are contacting with each other as well as with the backing plate and the rotor, computer-aided engineering (CAE) analyses with high fidelity is required to simulate the test and turbine operating conditions. For this purpose, FE methodology has been developed for structural analyses of brush seals. Three-dimensional FE models of brush seals have been constructed and simulations have been performed for pressurized rotor-rub conditions. CAE model of brush seals includes rotor–bristle, bristle pack–backing plate, and interbristle contacts with friction. Simulations with nonrotating rotor and transient analyses with rotating rotor have been conducted, and the extracted bristle tip force (BTF) levels are correlated with the test results. Inertial effects during dynamic tests have also been simulated through transient analyses and results show good agreement with the dynamic test data. Displacement and stress profiles obtained from correlated FE models give better understanding of brush seal behavior under turbine operating conditions.

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References

Figures

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Fig. 1

High-speed RTR assembly photo

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Fig. 2

High-speed RTR photo

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Fig. 3

RTR-seal housing assembly details for pressurized-dynamic stiffness tests

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Fig. 4

RTR—bearing locations for GMN-HV-X 150-45000/25

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Fig. 5

RTR—assembly and bearing modeling details

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Fig. 6

First elastic mode, first-order bending about y-axis: (a) eigenmode contour and (b) element strain energy contour

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Fig. 7

Second elastic mode, first-order bending about y-axis: (a) eigenmode contour and (b) element strain energy contour

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Fig. 8

RTR-rotary component assembly, FRF analyses details

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Fig. 9

RTR-rotary component assembly, FRF analyses results

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Fig. 10

Test seal design parameters

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Fig. 11

Sections for microscopic inspection of NRs

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Fig. 12

Microscopic inspection of test seal #1

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Fig. 13

Microscopic inspection of test seal #2

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Fig. 14

BTF change with radial interference, effect of pressure load on RTR—static stiffness measurements

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Fig. 15

BTF comparison for pressurized-static and pressurized-dynamic measurements, ΔP = 2.25 bar

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Fig. 16

BTF comparison for pressurized-static and pressurized-dynamic measurements, ΔP = 3 bar

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Fig. 17

Brush seal CAE model with B31 elements—CAE model details

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Fig. 18

Pressurized, nonrotating rotor rub for test seals—CAE-B31, analysis steps

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Fig. 19

Pressurized, nonrotating radial interference for test seals—CAE-B31, BTF results, and comparison with test, ΔP = 0.3 MPa

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Fig. 20

Pressurized, nonrotating radial interference for test seals—CAE-B31, BTF results, and comparison with test, ΔP = 0.225 MPa

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Fig. 21

Transient CAE analysis steps—pressurized-rotating rotor rub for test seals

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Fig. 22

Pressurized-dynamic radial interference—BTF results of CAE analyses and comparison with test at ΔP = 0.3 MPa

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Fig. 23

Pressurized-dynamic radial interference—BTF results of CAE analyses and comparison with test at ΔP = 0.225 MPa

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Fig. 24

Pressurized, nonrotating rotor rub for test seals—CAE-B31, VM stress profile at ΔP = 0.3 MPa

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