Dynamic characteristics of hydrodynamically lubricated fixed-pad thrust bearings

Abstract

Experiments [N. Mittwollen, T. Hegel, J. Glienicke. Effects of hydrodynamic thrust bearings on lateral shaft vibrations, Journal of Tribology, 113 (October 1991) 811–818] have shown that hydrodynamic thrust bearings may influence lateral rotor vibrations significantly. The purpose of this study was to develop fast computational routines to evaluate the main dynamic coefficients for hydrodynamically lubricated tapered land bearings, and to use a solution method that could be extended to tilting-pad, and misaligned bearings. The Reynolds equation for thin film lubrication is solved by using a one-dimensional finite element technique and an assumed pressure profile in the radial direction. Thermal effects are included by solution of the one-dimensional energy equation using a forward Euler finite difference technique. Dynamic coefficients are retrieved for fixed pad thrust bearings by numerical differentiation about the steady state solution. The effects of various geometrical factors, such as pad length-to-width, inner-to-outer radius ratio have been studied. Results are compared to a two-dimensional perturbation solution and they agree well within the engineering accuracy desired.