Design functions for hydrodynamic bearings

Abstract

Designing hydrodynamic bearings usually requires a total numerical analysis of the pressure distribution and corresponding design quantities such as the load capacity, load position, oil flowrate, power loss, coefficient of friction and relative power loss. Another option is to determine the design quantities from design diagrams, which may give rise to inaccurate results, especially if interpolation between the curves is needed. Instead, it would have been better to have functions describing the design quantities. The objective of this work is to determine curve-fitted functions describing each design quantity, by following a well-defined procedure. Three different kinds of geometry are analysed: rectangular tilting-pad thrust bearings, sector-shaped tilting-pad thrust bearings and journal bearings with two axial oil grooves. In addition, an optimum analysis is performed. The approximate design functions obtained in this work show very good resemblance to the numerically calculated results, and they are valid for a wide range of the geometric parameters. The intention is to use the functions in programmable pocket calculators or implemented short computer programs, making them a very fast and accurate alternative to a complete numerical analysis in bearing design. Finally, the functions concerning the optimum analysis saves a large amount of time compared with a traditional analysis.