Characteristics of Externally Pressurized Journal Bearings with Membrane-Type Variable-Flow Restrictors as Compensating Elements

Abstract

The characteristics of externally pressurized journal bearings with four recesses and with membrane-type variable-flow restrictors as compensating elements are analytically investigated by using the bearing model of Raimondi and Boyd. The effects of the ratio of the recess pressure at zero eccentricity to the supply pressure (pressure ratio), the eccentricity ratio, the compliance of the membrane and the shaft rotation on the lubricant flow rate, the load capacity and the stiffness of these bearings are presented for a given aspect ratio and interrecess land width-to-diameter ratio. For a non-rotating shaft, it is shown that when the bearing operates at zero eccentricity there is a pressure ratio that gives an optimum bearing stiffness. This pressure ratio is a function of the aspect ratio of the bearing only. Using this pressure ratio, data for the load capacity and stiffness of the bearing are presented for an eccentricity ratio that varies from 0 to 0.1. For these data, the membrane compliances used are those that would give an infinite bearing stiffness if the bearing were operating at zero eccentricity.

A Historical Review of Gas Lubrication: From Reynolds to Active Compensations

“…In journal bearings, membrane type variable flow restrictors were used as compensating elements. In 1974, Cusano [20] proposed an externally pressurised journal bearing that employed elastic membranes to vary bearing exhausting flow, and compensating load variations. At the beginning of the nineties, Mizumoto [21] and Yoshimoto et al [22] were the first to employ movable restrictors to compensate load variations.…”

An improved lumped parameter method for calculating static characteristics of multi-recess hydrostatic journal bearings

“…Using the TLPM, 10 the flow continuity equation can be expressed as where h¯i 3=1π/2-θr∫θit θit+π/2-θrh¯3dθ, h¯i=1π/2-θr∫θit θit+π/2-θrh¯dθ, Δti=∫θil-(π/2-θr)/2 θit+(π/2-θr...…”

“…O'Donoghue et al 9 compared the procedures of the simple concentric theory, the LPM, and the FDM for designing multi-recess hydrostatic journal bearings from the aspects of accuracy, cost, and ease of use. Ms 10 adopted the LPM to research the influences of the pressure ratio, the eccentricity ratio, the compliance of the membrane, and the shaft rotation on the static characteristics of membrane compensated multi-recess hydrostatic journal bearing. Bassani 11 presented a procedure of the LPM, incorporating turbulence and inertia edge effects, to forecast the static characteristics of hydrostatic journal bearings fed with cryogenic fluids.…”

Semi-Analytical Analysis of a Rigid Rotor Mounted on Four-Pad Hydrostatic Squeeze Film Damper with Single-Action Membrane-Type Restrictors

“…Generally, there are two types of compensation: passive compensation, such as orifice and capillary restrictors, and active compensation [7][8][9][10]. In passively compensated bearings, the geometry of the compensating element never changes.…”

“…In several works, contributions to the study of the behaviour of these externally pressed bearings with variable flow constraints have been made by Digast et al [7], Mayer and Shaw [8], O'Donoghue and Rowe [9] and Cusano et al [10]. The double diaphragm valve (membrane) was developed for grinding machine slide ways and spindle supports.…”