A Novel Variable Impedance Hydrodynamic Oil-Film Bearing: Part 1: Theoretical Modelling

Abstract

A novel bearing design is presented. The bearing consists of a partial arc bearing into which two recesses are machined. Attached to the two recesses, via remote-controlled valves, are two accumulators. The ability to be able to open and close the valves gives the new bearing design four independent operating modes. Steady state operating characteristics for the bearing were predicted using a finite difference solution to Reynolds' equation. A new mathematical model is proposed for the recess boundary. The model is based on flow continuity and enables a finite difference node to be positioned on the recess boundary. It is demonstrated that the theoretical model proposed predicts steady state characteristics which agree favourably with previously published work and with experimental data. The model was further utilized, in a pressure perturbation algorithm, to obtain predictions of the bearing's dynamic operating characteristics. It is demonstrated that by switching the valves from open to closed, or vice versa, the bearing's characteristics can be altered in situ. It is also demonstrated that the inclusion of the recesses and accumulators has little effect on the steady state characteristics when compared to those of a conventional partial arc bearing. It is suggested that the bearing design proposed in this paper has major advantages to offer the rotating machine designer. Use of the bearing enables the operator to vary support characteristics without major re-machining. Furthermore, support characteristics may be varied in situ, without significant cost penalties and with little additional maintenance overheads.