Advanced cryogenic fluid turbopumps are very compact, operate at extremely high shaft speeds, and require hybrid (hydrostatic/hydrodynamic) radial and thrust fluid film bearings for accurate rotor positioning. Sound design and reliable operation of fluid film thrust bearings also allows for unshrouded impellers with a significant increase in the turbopump mechanical efficiency. A bulk-flow analysis for prediction of the static load performance and dynamic force coefficients of high speed, angled injection orifice-compensated, hybrid (hydrostatic/hydrodynamic) thrust bearings is presented. The model accounts for the bulk-flow mass, momentum and thermal energy transport, and includes flow turbulence and fluid inertia (advection and centrifugal) effects on the bearing film lands and recesses. The performance of a refrigerant hybrid thrust bearing for an oil-free air conditioning equipment is evaluated at two operating speeds and pressure differentials. The computed results are presented in dimensionless form to evidence consistent trends in the bearing performance characteristics. As the applied axial load increases, the bearing film thickness and flow rate decrease while the recess pressure increases. The axial stiffness coefficient shows a maximum for a certain intermediate load while the damping coefficient steadily increases with load. The computed results show the significance of centrifugal fluid inertia at low recess pressures (i.e. low loads) and high rotational speeds, and which can lead to film starvation at the bearing inner radius and subambient pressures just downstream of the bearing recess edge. [S0742-4787(00)02201-3]
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January 2000
Technical Papers
Bulk-Flow Analysis of Hybrid Thrust Bearings for Process Fluid Applications
Luis San Andre´s
Luis San Andre´s
Mechanical Engineering Department, Texas A&M University, College Station, TX 77843-3123
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Luis San Andre´s
Mechanical Engineering Department, Texas A&M University, College Station, TX 77843-3123
Contributed by the Tribology Division of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS and presented at the STLE/ASME Tribology Conference. Orlando, Fl, October 10–13, 1999. Manuscript received by the Tribology Division January 12, 1999; revised manuscript received June 10, 1999. Paper No. 99-Trib-20. Associate Technical Editor: D. P. Fleming.
J. Tribol. Jan 2000, 122(1): 170-180 (11 pages)
Published Online: June 10, 1999
Article history
Received:
January 12, 1999
Revised:
June 10, 1999
Citation
San Andre´s , L. (June 10, 1999). "Bulk-Flow Analysis of Hybrid Thrust Bearings for Process Fluid Applications ." ASME. J. Tribol. January 2000; 122(1): 170–180. https://doi.org/10.1115/1.555340
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