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Research Papers

Multiple Frequencies Elliptical Whirling Orbit Model and Transient RANS Solution Approach to Rotordynamic Coefficients of Annual Gas Seals Prediction

[+] Author and Article Information
Jun Li

e-mail: junli@mail.xjtu.edu.cn

Xin Yan

Institute of Turbomachinery,
Xi'an Jiaotong University,
Xi'an 710049, China

1Corresponding author.

Contributed by the Design Engineering Division Journal of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received February 17, 2012; final manuscript received November 8, 2012; published online March 28, 2013. Assoc. Editor: Yukio Ishida.

J. Vib. Acoust 135(3), 031005 (Mar 28, 2013) (14 pages) Paper No: VIB-12-1041; doi: 10.1115/1.4023143 History: Received February 17, 2012; Revised November 08, 2012

A numerical method using the multiple frequencies elliptical whirling orbit model and transient Reynolds-averaged Navier–Stokes (RANS) solution was proposed for prediction of the frequency dependent rotordynamic coefficients of annular gas seals. The excitation signal was the multiple frequencies waveform that acts as the whirling motion of the rotor center. The transient RANS solution combined with mesh deformation method was utilized to solve the leakage flow field in the annular gas seal and obtain the transient response forces on the rotor surface. Frequency dependent rotordynamic coefficients were determined by transforming the dynamic monitoring data of response forces and rotor motions to the frequency domain using the fast fourier transform. The frequency dependent rotordynamic coefficients of three types of annular gas seals, including a labyrinth seal, a fully partitioned pocket damper seal and a hole-pattern seal, were computed using the presented numerical method at thirteen or fourteen frequencies of 20–300 Hz. The obtained rotordynamic coefficients of three types of annular gas seals were all well agreement with the experimental data. The accuracy and availability of the proposed numerical method was demonstrated. The static pressure distributions and leakage flow rate of three types of annular gas seals were also illustrated.

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References

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Figures

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Fig. 1

Geometries parameters of three types of annular gas seals

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Fig. 2

Computational models of three types of annular gas seals

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Fig. 3

Computational mesh of three types of annular gas seals

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Fig. 4

Axial view of the rotor and stator for the FPDS (concentric)

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Fig. 5

Elliptic orbit whirling model for the rotor vibration with a single frequency (eccentric)

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Fig. 6

Multiple frequencies whirling motion orbit of the rotor

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Fig. 7

Dynamic monitoring data: rotor motion (x excitation, HPS)

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Fig. 8

Dynamic monitoring data: response force (x excitation); (a) LABY, (b) FPDS, (c) HPS

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Fig. 9

Rotordynamic coefficients of the LABY

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Fig. 10

Rotordynamic coefficients of the FPDS

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Fig. 11

Rotordynamic coefficients of the HPS

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Fig. 12

Static pressure contours on the rotor surface (left) and the cross section (right) through the middle of: (a) cavity 7 of the LABY, (b) cavity 3 of the FPDS, and (c) the HPS, for x-direction excitation case at the time instance Tstep = 500

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