Performance of a Small Hydrodynamic Journal Bearing Involving Adsorbed Layer and Surface Elastic Deformation

Abstract

The load and friction performances of a small elastohydrodynamic journal bearing with the shaft radius 1mm have been computationally studied. The effect of the adsorbed layer is incorporated and the multiscale hydrodynamic flow theory is used. It is shown that the multiscale performance of this bearing occurs in the wide eccentricity ratio range from 0.3 to nearly unity because of the influence of the adsorbed layer, and thus the generated pressures and carried load of this bearing are significantly greater than the classical hydrodynamic theory calculations. The effect of the adsorbed layer is more stronger for rigid bearing surfaces than for elastic bearing surfaces especially for a strong fluid-bearing surface interaction, and it is strong for the high eccentricity ratios over 0.9. In this bearing, when the effect of the adsorbed layer is incorporated, the friction coefficients on both bearing surfaces are reduced in the wide eccentricity ratio range as compared to the classical calculation; Stronger the fluid-bearing surface interaction, greater the reduction of the friction coefficient, showing the pronounced non-continuum effect of the adsorbed layer. However, for elastic surfaces the friction coefficient is a bit higher than that for rigid surfaces especially for high eccentricity ratios and strong fluid-bearing surface interactions.