Dynamics of a rotor-bearing system equipped with a hydrodynamic thrust bearing

The effect of a hydrodynamic thrust bearing on the dynamics of a rotor-bear ing system is investigated systematically in this paper. The action of a th rust bearing is described as forces and moments in a static state and a ser ies of dynamic coefficients in a dynamic state which are calculated from th e Reynolds equation and its perturbed forms by using the boundary elements method. A lumped-mass model for system motion based on the Myklestad transf er matrix method is formulated considering the effects of thrust bearings a nd axial load. An interative procedure is proposed to sovle the indetermina te problem of load-sharing among journal bearings due to the introduction o f thrust bearings. The effects of such parameters as stiffness of shaft, st atic loads of journal bearings, position of lumped mass, position of thrust bearing and arrangement of thrust bearings on the action of thrust bearing s are discussed. The nature of this action reveals that thrust bearings not only provide stiffness and damping in a dynamic state, but also change the static deflection of the shaft, and thereby influence the static load-shar ing of journal bearings. The present research helps to explain the variatio n of dynamic characteristics of a machine due to the introduction of thrust bearings, and also provide theoretical basis for the dynamic design consid ering the effect of thrust bearings. (C) 1999 Academic Press.