Seizure of a High-Speed Three-Wave Journal Bearing

Abstract

This paper is focused on the geometry and operating parameters of the bearing experimentally studied at NASA Glenn Research Center by F. Dimofte. It presents two simple thermoelastohydrodynamic (TEHD) models for two typical mechanisms of seizure of a three-wave journal bearing: seizure during start-up under normal lubrication, respectively seizure induced by lubricant starvation. A quasi-concentric bearing, typical for high speed applications is analyzed. Shaft thermal expansion and a relationship between the viscosity and clearance are considered in a simplified manner. During start-up, the heat produced by viscous friction is assumed to be rejected only by the oil flow. Under starvation condition, the heat is assumed to be rejected only through the housing. For each case, a complex critical dimensionless number (called seizure number) which states the bifurcation between stable and unstable condition is defined. The predicted results obtained with these models have been validated on the case- experimentally studied at NASA.