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2 International Journal of Applied Mechanics and Engineering

2 2002

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Numerical modeling and design of a wavy thrust bearing

100%

Choy F. K. , Braun M. J. , Zhao H.

International Journal of Applied Mechanics and Engineering

2002

tom Vol. 7, no 3

757-769

The objective of this paper is to present the analytical and numerical development leading to the simulation of a wavy thrust bearings. The analytical formulation is based on the application of the Reynolds equation to the geometry of two parallel circular plates with prescribed boundary conditions at their inner and outer circumferential edges. The upper plate is assumed to be rotating while the lower plate, which is wavy in geometry, is stationary. A numerical procedure based on the discretisation of the Reynolds equation yields a finite difference formulation that reduces the second order partial differential equation to a set of simultaneous algebraic equations. For a given loading condition, the equilibrium position of the rotating plate is evaluated using the Newton-Raphson search, by balancing the applied load with the force generated by the hydrodynamic fluid film resisting pressure. The stiffness of the bearing is then calculated using a numerical small perturbation procedure at the equilibrium position of the upper plate. Finally the transient motion of the journal is evaluated using a numerical integration scheme on the translational and angular acceleration parameters. General and specific conclusions are drawn based on these numerical results.

An investigation of the shear and pressure flows interaction in a hydrostatic journal bearing pocket

100%

Braun M. J. , Peloso D. , Daniels C. C.

International Journal of Applied Mechanics and Engineering

2002

tom Vol. 7, no 3

739-747

The present paper studies parametrically the flow patterns and pressure profiles inside of, and on the adjoining seals of a single hydrostatic pocket, characteristic component of hydrostatic journal bearings. The major focus is on the interaction between the effects of the shear flow (Couette) created by the rotation of an eccentric shaft and the pressure induced flow due to hydrostatic jet penetrating at the bottom of the pocket. The pocket is square in nature with a size of 17.8mm x 17.8mm footprint. Its bottom surface has a radial sliding capability, such that the depth of the pocket can be changed, without breaking pocket integrity. This construction allows the study and ensuing comparison of the influence of changes in clearance, jet strength and shaft angular velocity on the flow patterns, pressure profiles and the combined hydrostatic and hydrodynamic effects. The flow structure of the jet and its interaction with the flow in the pocket itself is visualized qualitatively using long distance microscopy (up to x400). The PIV system used herein is equipped with a digital video-camera and a pulsing laser (30mJ/pulse) with a repetition capability of up to 5000Hz.