Combined influence of couple stress lubricant and geometric imperfections of journal on the performance of membrane compensated two-lobe hybrid journal bearing

This paper deals with the comparative performance of the two-lobe and circular hybrid journal bearing systems compensated with membrane restrictor. The combined influence of geometric imperfection of journal and the couple stress behaviour of the lubricant has been taken into the consideration. The non-Newtonian behaviour of the lubricant has been modelled using Stokes couple stress fluid model. The Reynolds equation has been modified to consider the couple stress fluid behaviour and has been solved by the FE Galerkin's approach. The numerically computed results from present study indicates that the couple stress lubricant presents an improved bearing performance in terms of stability (threshold speed), fluid film stiffness and damping coefficients vis-à-vis the corresponding bearing lubricated with Newtonian fluid. Further, the comparative performance of this class of bearings has been evaluated for the capillary, orifice and CFV restrictors.