Research Papers

Static and Dynamic Coefficient Measurements for a Thrust Collar Used in an Integrally Geared Compressor

[+] Author and Article Information
Thomas Kerr

Turbomachinery Laboratory,
Texas A&M University,
College Station, TX 77843
e-mail: Tchandler1992@tamu.edu

Andrew Crandall

Turbomachinery Laboratory,
Texas A&M University,
College Station, TX 77843
e-mail: Arcranda@gmail.com

Dara Childs

Leland T. Jordan Professor
Turbomachinery Laboratory,
Texas A&M University,
College Station, TX 77843
e-mail: dchilds@turbo-lab.tamu.edu

Adolfo Delgado

Turbomachinery Laboratory,
Texas A&M University,
College Station, TX 77843
e-mail: adelgado@tamu.edu

Manuscript received June 22, 2018; final manuscript received September 27, 2018; published online March 14, 2019. Editor: Jerzy T. Sawicki.

J. Eng. Gas Turbines Power 141(5), 051020 (Mar 14, 2019) (8 pages) Paper No: GTP-18-1314; doi: 10.1115/1.4041654 History: Received June 22, 2018; Revised September 27, 2018

This paper introduces a test facility specifically designed to measure the axial stiffness and damping coefficients of an oil-lubricated thrust collar (TC). The geometry, load, and speeds of the test facility are representative of a production integrally geared compressor (IGC). Separate electric motors spin the shafts according to an assumed gear ratio; a pneumatic air piston loader provides a noncontacting, static thrust force; a remotely controlled impact hammer delivers a perturbation force; and eddy-current motion probes record the resulting vibration. The paper uses a one degree-of-freedom (1DOF) axial motion model that neglects the static and dynamic stiffness of the bull wheel (BW) and presents estimates of the TC oil-film dynamic coefficients for pinion spin speeds between 5 and 10 krpm, and static loads between 200 and 400 N, using time-domain (log-dec and damped period) and static load-deflection techniques. The measurements show that the TC oil-film develops appreciable stiffness (tens of MN/m), and the 1DOF model used here is inadequate for higher loads. Axial runout on the interfacing surfaces of the test facility TC and BW complicates parameter identification, but time-domain averaging effectively attenuates the runout while preserving the transient vibration that results from the impact hammer. Measurements of the TC oil-film stiffness, damping, and virtual mass coefficients are useful to machinery original equipment manufacturers (OEMs) or end-users seeking to predict or diagnose subsynchronous vibration in their machine that might be TC-related.

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San Andrés, L. , Cable, T. A. , Wygant, K. , and Morton, A. , 2015, “ On the Predicted Performance of Oil Lubricated Thrust Collars in Integrally Geared Compressors,” ASME J. Eng. Gas Turbines Power, 137(5), p. 052502.
Niederhauser, J. , 1925, “ Apparatus for Balancing the Axial Thrust in Single Helical Toothed Wheel Gearing,” U.S. Patent No. 1,548,545. https://patents.google.com/patent/US1548545
Sadykov, V. A. , and Shneerson, L. M. , 1968, “ Helical Gear Transmissions With Thrust Collars,” Russ. Eng. J., 48(1), pp. 31–34.
Langer, H. , 1982, “ Hydrodynamische Axialkraftübertragung bei Wellen Schnellaufender Getriebe,” Konstruktion, 34(12), pp. 473–478 (in German).
Simon, V. , 1984, “ Thermal Elastohydrodynamic Lubrication of Rider Rings,” ASME J. Tribol., 106(4), pp. 492–498. [CrossRef]
Barragan de Ling, F. , Evans, H. P. , and Snidle, R. W. , 1996, “ Thrust Cone Lubrication—Part 1: Elastohydrodynamic Analysis of Conical Rims,” Proc. Inst. Mech. Eng., Part J., 210(2), pp. 85–96. [CrossRef]
Parkins, D. , and Rudd, L. , 1996, “ Thrust Cone Lubrication—Part 3: A Test Facility and Preliminary Measured Data,” Proc. Inst. Mech. Eng., Part J., 210(2), pp. 107–112. [CrossRef]
Heß, M. , 2013, “ Der Vollschmierung auf der Spur,” Vol. 38, Technische Universität Clausthal: Institut für Maschinenwesen, Clausthal-Zellerfeld, Germany, pp. 121–138 (in German).
Cable, T. A. , San Andrés, L. , and Wygant, K. , 2016, “ On the Predicted Effect of Angular Misalignment on the Performance of Oil Lubricated Thrust Collars in Integrally Geared Compressors,” ASME J. Eng. Gas Turbines Power, 139(4), p. 042503. [CrossRef]


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Fig. 1

Two-stage, single-pinion, IGC. Adapted from Ref. [1].

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Fig. 2

The thrust collar test facility

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Fig. 3

View of the static loader cross section

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Fig. 4

Example impact hammer force in the time-domain (a) and frequency-domain (b)

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Fig. 5

High-rate instrumentation on the TCTF

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Fig. 6

Example axial vibration responses to hammer impact before averaging. Impact occurs at t = 95.94 ms.

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Fig. 7

Axial displacement after averaging 25 responses (a) and zoomed-in on the transient (b)

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Fig. 8

Relative displacement zr(t) as FZ0 increases

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Fig. 9

zr(Ω)(after averaging) amplitude spectrum for FZ0 values between 200 N and 800 N

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Fig. 10

Static load-deflection measurements for ωH = 5 krpm (○), 7.5 krpm (◊), and 10 krpm (◻). Thin, solid lines denote the best-fit exponential curve.

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Fig. 11

Measured and predicted KZ as a function of FZ0 for ωH = 5, 7.5, and 10 krpm

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Fig. 12

Free-body diagram for log-dec vibration model

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Fig. 13

Relative displacement, zr, between TC and BW for FZ0 = 300 N, and ωH = 7.5 krpm

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Fig. 14

Measured static and dynamic stiffness as a function of ωH

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Fig. 15

Measured and predicted CZ values versus ωH

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Fig. 16

Virtual mass coefficient versus ωH for three FZ0



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