Clearance and lubricant selection for avoiding seizure in a circumferential groove journal bearing based on a lumped model analysis

Abstract

This study presents a new simple lumped model for analyzing the thermally induced seizure of fully lubricated eccentric circumferential groove journal bearings (CGJB). The model represents a significant upgrade of a previous seizure lumped model developed by Pascovici & Kucinschi, in 2002. Main upgrades consist of: eccentric operation, introduction of hydrodynamic lubricant flow rate component, and evaluation of friction power losses based on the short bearing theory with Barwell's hypothesis on the divergent zone. The viscosity-temperature variation is replaced with Tipei's viscosity-clearance relationship, as in the previous model. The decrease of viscosity, as a consequence of temperature increase, does not always limit clearance loss, and the seizure process ends with a concentric journal-bushing merged system. Although CGJB's are less sensitive to this seizure mechanism, the threat still exists and must be avoided. As a result, bearing designers and users should check whether if several safe-operation criteria are met. A recent Institute Pprime experiment on CGJB's provided a base set of operating parameters, from which numerical simulations have been performed to determine in what conditions the CGJB fails, under thermally induced seizure. © AFM, EDP Sciences 2011.