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Research Papers: Gas Turbines: Structures and Dynamics

Frequency and Stability Analysis Method of Asymmetric Anisotropic Rotor-Bearing System Based on Three-Dimensional Solid Finite Element Method

[+] Author and Article Information
Ma Wei Meng

405 Group,
School of Energy and Power Engineering,
Beihang University,
Xueyuan Road 37, Haidian District,
Beijing 100191, China
e-mail: mwmeng87@126.com

Wang Jian Jun

405 Group,
School of Energy and Power Engineering,
Beihang University,
Xueyuan Road 37, Haidian District,
Beijing 100191, China
e-mail: wangjianjun@buaa.edu.cn

Wang Zhi

405 Group,
School of Energy and Power Engineering,
Beihang University,
Xueyuan Road 37, Haidian District,
Beijing 100191, China
e-mail: wangzi629@163.com

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 January 8, 2015; final manuscript received March 1, 2015; published online March 31, 2015. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(10), 102502 (Oct 01, 2015) (9 pages) Paper No: GTP-15-1014; doi: 10.1115/1.4029968 History: Received January 08, 2015; Revised March 01, 2015; Online March 31, 2015

An efficient analysis method is suggested to investigate the frequency characteristics and stability of asymmetric anisotropic rotor-bearing systems. Modifications are made to incorporate the effect of stator asymmetry into an existing three-dimensional (3D) solid finite element procedure developed for rotors with symmetric supports. The reduced ordered linear differential equations with periodic coefficients of the asymmetric anisotropic rotor model are established in the rotating frame. The frequency characteristics and stability of the obtained periodic time-varying coefficient differential equations are investigated based on Floquet theory and Hill's method. Numerical examples and experimental studies are presented to validate the effectiveness of the presented method.

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Copyright © 2015 by ASME
Topics: Stability , Bearings , Rotors
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References

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Figures

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Fig. 1

Typical analysis model of asymmetric anisotropic rotor system

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Fig. 2

Condensation of the boundary nodes to the center node

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Fig. 3

Flow chart of the presented 3D finite element stability analysis method

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Fig. 4

Sketch of an asymmetric Jeffcott rotor running on anisotropic bearings

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Fig. 5

Campbell diagram of a Jeffcott rotor with αn = 0.4,αr = 0.4, and β = 0.8, computed using jmax = 1

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Fig. 6

Decay rate plot of a Jeffcott rotor with αn = 0.4, αr = 0.4, and β = 0.8, computed using jmax = 1

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Fig. 7

3D solid finite element model of the noncircular cross section rotor

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Fig. 8

Imaginary and real part of the eigenvalues of the experimental setup in the rotating coordinate system: (a) imaginary part and (b) real part

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Fig. 9

Experimental setup of a rotor with noncircular shaft in adjustable anisotropic elastic bearings

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Fig. 10

Experimental signal frequency spectra of the asymmetric anisotropic rotor-bearing system: (a) for 420 rev/min and (b) for 540 rev/min

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Fig. 11

Numerical and experimental free whirling frequencies of the experimental setup in the fixed coordinate system

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