Load carrying capacity(LCC) can be reduced from its design value as a result of film thickness change when a journal is misaligned and some part of bearing is unintentionally translated. In this study, the numerical solution of the incompressible Reynolds equation was obtained by using the finite difference method and mass conservation algorithm (JFO boundary condition) with periodic pressure distribution in circumferential direction to analyze the change of LCC due to journal misalignment and step change of film thickness in axial direction for a journal bearing of vertical pumps. Smallest LCC in each eccentricity ratio is obtained as two angular positions are changed – an angular position where misalignment occurs, and another angular position where the axial step takes place while the degree of misalignment is fixed at 90%. Compared with the reaction force of plain journal bearing, the LCC reduced as much as 26.7% due to geometric effects of journal bearing at the eccentricity ratio of 0.9, while the step height is no higher than 0.1 times of bearing clearance.

• 최문호(한국수력원자력 중앙연구원 기계연구소)