Transient characteristics investigation on axis orbit of flexible pivot tilting pad hybrid bearing

Purpose The analysis on the convergence, stability and divergence degree of axis orbit can effectively evaluate the internal lubrication characteristics and operating state of journal bearing. This paper aims to propose a flexible pivot tilting pad hybrid bearing, the bearing combines the advantages of the hydrostatic bearing and tilting pad bearing, and analyzes the transient characteristics of the bearing rotor. Design/methodology/approach The mathematical model of rotor system supported by the flexible pivot tilting pad hybrid journal bearing is established. The transient characteristics of nonlinear axis trajectory under different loads are studied by Euler method. At the same time, the influence of unbalance load on the axis trajectory and motion parameters of bearing is studied. Findings The results show that when the bearing is not subjected to external load, the oil film force of bearing is all used to balance its own gravity; after reaching equilibrium state, the displacement of rotor, swing angle of each bush, nonlinear oil film force and maximum pressure cannot change. When the external load is unbalanced load, the motion parameters of bearing have been oscillating in the stable period; the larger the unbalanced load is, the larger the vibration amplitude of bearing motion parameters is. Originality/value The research is of great significance for improving the theory of tilting pad hybrid journal bearing and axis trajectory theory.