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Research Papers: Gas Turbines: Structures and Dynamics

Dynamic Leakage Analysis of Noncontacting Finger Seals Based on Dynamic Model

[+] Author and Article Information
Kaibing Du

State Key Laboratory of Tribology,
Tsinghua University,
Beijing 100084, China
e-mail: kaibdu@163.com

Yongjian Li

State Key Laboratory of Tribology,
Tsinghua University,
Beijing 100084, China
e-mail: liyongjian@tsinghua.edu.cn

Shuangfu Suo

Associate Professor
State Key Laboratory of Tribology,
Tsinghua University,
Beijing 100084, China
e-mail: sfsuo@tsinghua.edu.cn

Yuming Wang

Professor
State Key Laboratory of Tribology,
Tsinghua University,
Beijing 100084, China
e-mail: yumingwang@tsinghua.edu.cn

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 April 13, 2014; final manuscript received February 3, 2015; published online February 25, 2015. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(9), 092501 (Sep 01, 2015) (7 pages) Paper No: GTP-14-1195; doi: 10.1115/1.4029776 History: Received April 13, 2014; Revised February 03, 2015; Online February 25, 2015

Noncontacting finger seals are new compliant seal in gas turbine engine sealing technology. Their potential hydrodynamic and hydrostatic lifting capabilities make them preferable to brush seals and contacting finger seals. The work concerns the mechanism of dynamic leakage of noncontacting finger seal, and a novel dynamic leakage analysis model is proposed. The model combines seal dynamic analysis and seal leakage analysis together to estimate seal dynamic performance through seal leakage. The nature of dynamic leakage performance affected by the change of seal–rotor clearance is revealed. Dynamic leakage increasing is mainly affected by ratio of friction force to finger stiffness, finger mass natural frequency, and rotor excitation amplitude. Results show that the leakage increasing caused by the rotor eccentricity is inevitable. In the design optimization of the noncontacting finger seal, the ratio of friction force to finger stiffness and the rotor excitation should be as small as possible, and the finger natural frequency should be as large as possible.

Copyright © 2015 by ASME
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References

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Figures

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Fig. 4

(a) Dynamic model during coupled seal/rotor motion and (b) dynamic model during uncoupled seal/rotor motion

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Fig. 3

Equivalent mass–spring–damper representation

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Fig. 2

Schematic of noncontacting finger seal

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Fig. 1

The flow diagram of the method

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Fig. 5

Gas film underneath LP finger pad and its boundary conditions

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Fig. 6

Simulation of finger mass motion response to rotor interaction (μ = 0.1)

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Fig. 7

Transient mass flow rates under finger mass (μ = 0.1)

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Fig. 8

Simulation of finger mass response to rotor interaction (variable μ)

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Fig. 9

Clearance increment between finger mass and rotor surface (variable μ)

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Fig. 10

Equivalent dynamic mass flow rates for a full seal (variable μ)

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Fig. 13

Simulation of finger mass response to rotor interaction (variable wf)

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Fig. 14

Clearance increment between finger mass and rotor (variable wf)

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Fig. 15

Equivalent dynamic mass flow rates for a full seal (variable wf)

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Fig. 12

Equivalent dynamic mass flow rates for a full seal (variable z0)

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Fig. 11

Simulation of finger mass response to rotor interaction: (a) z0 = 25 μm, (b) z0 = 20μm, (c) z0 = 7μm, and (d) z0 = 2 μm

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