Compensation of Cross-Coupling Stiffness and Increase of Direct Damping in Multirecess Journal Bearings Using Active Hybrid Lubrication: Part I—Theory

Abstract

Fluid film forces are generated in hydrostatic journal bearings by two types of lubrication mechanisms: the hydrostatic lubrication in the bearing recesses and hydrodynamic lubrication in the bearing lands, when operating in rotation. The combination of both lubrication mechanisms leads to hybrid journal bearings (HJB). When part of hydrostatic pressure is also dynamically modified by means of hydraulic control systems, one refers to the active lubrication. The main contribution of the present theoretical work is to show that it is possible to reduce cross-coupling stiffness and increase the direct damping coefficients by means of the active lubrication, what leads to rotor-bearing systems with larger threshold of stability.