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Research Papers: Gas Turbines: Structures and Dynamics

Experimental Analysis of Angled Injection Aerostatic Hybrid Bearings

[+] Author and Article Information
Julian Le Rouzic, Mihai Arghir

PPRIME Institute,
UPR CNRS 3346,
Université de Poitiers,
ENSMA ISAE,
Chasseneuil Futuroscope 86962, France

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 20, 2017; final manuscript received July 21, 2017; published online October 10, 2017. Editor: David Wisler.

J. Eng. Gas Turbines Power 140(2), 022504 (Oct 10, 2017) (8 pages) Paper No: GTP-17-1381; doi: 10.1115/1.4037873 History: Received July 20, 2017; Revised July 21, 2017

Counter-rotation angled injection employed for aerostatic hybrid bearings reduces the cross coupling stiffness that may lead to whirl–whip instabilities at high rotation speeds. The benefits of counter-rotation injection have been known for years. Theoretical investigations were performed for water or air fed hybrid bearings but experiments were conducted only for water fed bearings. The present work is the first effort dedicated to angled injection in air fed hybrid bearings. The tests were performed for a simple rotor supported by two identical hybrid bearings. The hybrid bearings are provided with small size, shallow pockets and are fed with air via counter-rotation-oriented orifice type restrictors. An impulse turbine fed with air entrains the rotor. An impact gun applies dynamic excitations and the rotordynamic coefficients are identified from the equations of motion of the rotor. Different air feeding pressures are tested as well as high rotational speeds. Compared to the dynamic characteristics of radial injection hybrid bearings, the direct stiffness of counter-rotation injection bearings has slightly lower values and the direct damping is higher but the main impact is the drastic reduction of the cross-coupling stiffness that may have even negative values.

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References

Tondle, A. , 1967, “ Bearings With a Tangential Gas Supply,” Gas Bearing Symposium, Southampton, UK, Apr. 25–28, Paper No. 4.
Franchek, N. , and Childs, D. , 1994, “ Experimental Test Results for Four High-Speed, High Pressure, Orifice-Compensated Hybrid Bearings,” ASME J. Tribol., 116(1), pp. 147–153. [CrossRef]
San Andrés, L. , and Childs, D. , 1997, “ Angled Injection—Hydrostatic Bearings, Analysis and Comparison to Test Results,” ASME J. Tribol., 119(1), pp. 179–187. [CrossRef]
Laurant, F. , and Childs, D. , 1999, “ Rotordynamic Evaluation of a Near-Tangential-Injection Hybrid Bearing,” ASME J. Tribol., 121(4), pp. 886–891. [CrossRef]
San Andrés, L. , Soulas, T. , Challier, F. , and Fayolle, P. , 2002, “ A Bulk-Flow Model of Angled Injection Lomakin Bearings,” ASME Paper No. GT2002-30287.
Hélène, M. , Arghir, M. , and Frêne, J. , 2004, “ Combined Navier–Stokes and Bulk-Flow Analysis of Hybrid Bearings: Radial and Angled Injection,” ASME J. Tribol., 127(3), pp. 557–567. [CrossRef]
Arghir, M. , Hélène, M. , and Frêne, J. , 2005, “ Analysis of Tangential-Against-Rotation Injection Lomakin Bearings,” ASME J. Eng. Gas Turbines Power, 127(3), pp. 781–790. [CrossRef]
Tamunodukobipi, D. , Kim, C. H. , and Lee, Y.-B. , 2014, “ Dynamic Performance Characteristics of Floating-Ring Bearings With Varied Oil-Injection Swirl-Control Angles,” ASME J. Dyn. Syst. Meas. Control, 137(2), p. 021002. [CrossRef]
Rudloff, L. , Arghir, M. , Bonneau, O. , Guingo, S. , Chemla, G. , and Renard, E. , 2012, “ Experimental Analysis of the Dynamic Characteristics of a Hybrid Aerostatic Bearing,” ASME J. Eng. Gas Turbines Power, 134(8), p. 082503. [CrossRef]
De Santiago, D. O. C. , 2002, “ Identification of Bearing Supports' Force Coefficients From Rotor Responses Due to Imbalances and Impact Loads,” Ph.D. thesis, Texas A&M University, College Station, TX.
Amoser, M. , 1995, “ Stromungsfelder und Radialkrafte in Labyrinthdichtungen Hydraulischer Stromungsmaschinen,” Ph.D. dissertation, ETH Zurich, Zürich, Switzerland.

Figures

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Fig. 1

Cut view of an aerostatic bearing with typical pockets

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Fig. 2

Cut view and side view of the test rig [8]

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Fig. 3

Measured torque of the counter-rotation angled injection bearing

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Fig. 4

The rigid rotor and the coordinate system [9]

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Fig. 5

Impact force versus time for Ps = 3 bar and Ω = 40 krpm

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Fig. 6

Displacement x1 versus time for Ps = 3 bar and Ω = 10 krpm

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Fig. 7

Displacement x1 after impact versus time for Ps = 3 bar and Ω = 10 krpm (before filtering)

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Fig. 8

Displacement x1 after impact versus time for Ps = 3 bar and Ω = 10 krpm (after filtering)

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Fig. 9

Displacement x1 after impact versus time for Ps = 3 bar and Ω = 50 krpm (before filtering)

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Fig. 10

Displacement x1 after impact versus time for Ps = 3 bar and Ω = 50 krpm (after filtering)

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Fig. 11

Direct stiffness K versus frequency for Ps = 3 bar and Ω = 40 krpm

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Fig. 12

Cross-coupling stiffness k versus frequency for Ps = 3 bar and Ω = 40 krpm

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Fig. 13

Direct damping C versus frequency for Ps = 3 bar and Ω = 40 krpm

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Fig. 14

Cross-coupling damping c versus frequency for Ps = 3 bar and Ω = 40 krpm

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Fig. 15

Direct stiffness K versus Ps for different speeds for angled injection

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Fig. 16

Direct damping C versus Ps for different speeds for angled injection

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Fig. 17

Cross-coupling stiffness k versus Ps for different speeds for angled injection

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Fig. 18

Cross-coupling damping c versus Ps for different speeds for angled injection

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Fig. 19

Direct stiffness K versus Ps for different speeds for angled and radial injection [9]

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Fig. 20

Direct damping C versus Ps for different speeds for angled radial injection [9]

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Fig. 21

Cross-coupling stiffness k versus Ps for different speeds for angled radial injection [9]

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Fig. 22

Cross-coupling damping c versus Ps for different speeds for angled radial injection [9]

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