The influences of capillary restriction and journal eccentricity on the stability of the rigid rotor‐hybrid bearing system

Abstract

PurposeThe present paper proposes a theoretical analysis of the stability characteristics of a rigid rotor‐hybrid bearing system. It is intended that on the basis of the numerical results drawn from this study, the optimal restriction parameter for stable operation can be determined for use in the bearing design process.Design/methodology/approachA rigid rotor supported by hybrid oil film bearings with six recesses and capillary‐compensated restrictors is studied. In order to facilitate the calculation of film dynamics, using the perturbation method, the Reynolds equation was linearized and subsequently solved using finite difference techniques, whilst the stability maps were determined by the Routh‐Hurwitz method.FindingsThe data reported here suggest that the stability characteristics of the rigid rotor‐bearing system could be improved by the use of shallow, dual‐recessed hybrid bearings with capillary compensation. For the same restriction parameter and the same land‐width ratio used in large eccentricity case the stability characteristics of a shallow‐recessed bearing is superior to that of a deep‐recessed bearing, however, a deep‐recessed bearing with a small land‐width ratio and a small restriction parameter can provide better stability than a shallow‐recessed bearing with a large land‐width ratio or with a large restriction parameter.Originality/valueThis study proposes an extensive database as a critical requirement in the design of hybrid bearings, in order to ensure that a rotor bearing system is operating stably.