Stability of multilobe hybrid bearing with short sills—part II

A small amplitude perturbation analysis has been carried out to determine the rotordynamic characteristics of multilobe hybrid bearings with short axial and circumferential sills. Unsteady state recess flow continuity equation has been written for orifice compensated bearing in terms of dynamic recess pressures by perturbing steady state flow equation. Dynamic recess pressures are evaluated by solving unsteady recess flow continuity equations to determine the dynamic load capacity of the bearing. Stiffness and damping coefficients of the bearing are determined from the dynamic load capacity of the bearing. Results of dynamic characteristics of three lobe and four lobe hybrid bearings are presented for various offset factors, speed, concentric pressure and eccentricity ratios. Multilobe hybrid bearings with offset factors more than one are found to exhibit better dynamic behaviour than circular hybrid bearings.