Performance Characteristics of Journal Bearings with Vertical Shaft

Journal bearings are widely used in rotating shafts machineries. A small clearance provided between the bearing bush and the shaft (journal) consists of a thin film of lubricant, which allows for free rotation. The rapid rotation of the journal leads to a hydrodynamic action, thus generating a pressure profile in the lubrication film. In the past, numerous studies have been conducted to obtain the performance characteristics of journal bearings. However, they have been majorly limited to bearings with horizontal shafts. In this study, a detailed theoretical analysis of journal bearing with a vertical shaft is presented. It is based on a finite difference approach applied to Reynolds’ equation, obtaining the static and dynamic pressure distribution produced by a small journal perturbation. Integration of the steady state pressure distribution yields the load-carrying capacity, while the integration of the pressure gradients with respect to the displacement and velocity yields the stiffness coefficients and damping coefficients, respectively. A benchmark study on an axial groove bearing has validated the estimated methodology. Finally, orbit plots for vertical shaft bearings are presented, indicating the position of the shaft at various load values.