Abstract

ANTONIO-GARCIA, A.; LINARES-FLORES, J.  and  ARIAS-MONTIEL, M.. Numerical Investigations of the Lubrication Conditions in Hydrodynamic Bearings with Shaft Misalignment Effect. Ing. invest. y tecnol. [online]. 2013, vol.14, n.1, pp.89-98. ISSN 2594-0732.

The radial hydrodynamic bearings are widely used to support loads in rotating machines that operate at high speed. Theoretically, hydrodynamic bearings are designed for infinite life, but the precision machining, heating or misalignment with the rotor can contribute to performance problems and undesired wear. A problem that cannot be eliminated is the shaft angular misalignment caused by the weight and flexibility of the rotor. Misalignment changes the lubricant film thickness affecting the conditions of hydrodynamic lubrication. In this paper, a numerical investigation of the behavior of the pressure field, axial flow, film thickness and viscous friction considering the misalignment of the shaft by the effect of the weight and flexibility of the rotor, is presented. The hydrodynamic pressure field is solved using the equation of Reynolds lubrication with a modified expression of film thickness including the shaft misalignment. An expression to calculate the maximum misalignment allowed by a bearing based on the equilibrium steady state is also presented. The results show that as the shaft misalignment increases, a reduction in the film thickness is present, causing an increase in both maximum pressure and axial flow of lubricant, and also small changes in viscous drag. In order to validate the numerical results obtained in this investigation they were compared with numerical results reported in international literature, giving a good approximation.

Keywords : hydrodynamic bearings; misalignment; axial flow; film thickness; viscous friction.

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