B.C. Majumdar

Rotordynamic coefficients of multirecess hybrid journal bearings part I

Abstract Rotordynamic coefficients of a multirecess hybrid bearings have been evaluated following first-order perturbation of the dynamic Reynolds equation. Frequency effects on the rotordynamic coefficients are observed for high frequency vibrations for bearings with deep recesses. Results are presented for a capillary-compensated four-recess journal bearing.

Externally pressurized gas bearings: A review

Abstract The literature pertaining to externally pressurized hole admission gas bearings is briefly reviewed. The advantages, limitations and applications of such bearings under various design conditions are discussed.

Temperature distribution in oil journal bearings

Abstract A series of tests was conducted to determine the temperature distribution of a journal bearing using an incompressible lubricant. The journal diameter was 31.50 mm and the length to diameter ratio was equal to 1. Results obtained at a diametrical clearance of 0.0508 mm over a speed range of 2000 to 3000 r.p.m. with radial loads up to 9.5 kg and oil supply pressures from 0 to 4 kg/cm 2 show that load capacity is generally less than that predicted by the classical isothermal theory.

Rotordynamic coefficients of multirecess hybrid journal bearings Part II: Fluid inertia effect

Abstract The effect of fluid inertia over the sill area on the rotordynamic coefficients of multirecess hybrid bearings has been investigated here. It has been shown that only the direct stiffness coefficients amongst the various rotordynamic coefficients are influenced by the inclusion of a fluid inertia effect over the sills. It has been found that the fluid inertia effect, when taken into account, reduces the dynamic stiffness coefficients. Therefore it manifests itself in the form of apparent mass or inertia in the system. Results are presented for a four-recess capillary-compensated hybrid journal bearing.

Analysis of externally pressurized gas bearings with journal rotation

Abstract Theoretical studies of rotating externally pressurized gas bearings with multiple pressure sources have been made. The solution is obtained for finite bearings by using pressure perturbation theory. Theoretical results are compared with experimental data. The theory allows good prediction of bearing load capacity, stiffness and attitude angle.

Stability of submerged four-lobe oil journal bearings under dynamic load

Abstract A non-linear transient method was used to predict the journal centre trajectory for a submerged four-lobe oil journal bearing under (1) unidirectional constant load, (2) unidirectional periodic load, and (3) variable rotating load. The Reynolds equation was integrated using the Jakobsson-Floberg-Olsson cavitation zone model, and oil film prehistory effects were taken into account. The journal centre trajectories obtained were compared with those obtained for submerged plain cylindrical bearings under similar loading conditions. It was observed that the excursions of the journal centre were subdued, unlike for the plain cylindrical bearings, where the journal centre had a large excursion before it became stable or ended in a limit cycle. Interesting trajectories were observed for the periodic load. A three-dimensional plot of the pressure distribution in the bearing clearance was obtained using computer graphics.

Multi-recess hydrostatic oil journal bearings with cyclic squeeze

Abstract A theoretical estimate of bearing characteristics is made for multi-recess hydrostatic oil journal bearings with sinusoidal squeeze film. Performance curves of a finite journal bearing having four recesses are given for various bearing design parameters, eccentricity ratios and squeeze numbers.

The numerical solution of aerostatic journal bearings with several supply ports

Abstract An analysis concerning load, flow and stiffness of an aerostatic journal bearing with several supply holes is made using a numerical method of solution. Bearing performance curves are presented for various bearing design parameters. A design procedure either for maximum load or maximum stiffness of a finite bearing is also indicated.

Analysis of stiffness and damping characteristics of externally pressurized gas-lubricated porous bearings under conical mode of vibration

Abstract This work gives a theoretical analysis of the dynamic behaviour of externally pressurized gas-lubricated porous bearings with journal rotation and with regard to the stiffness and damping in the conical mode of vibration. The theoretical analysis has been obtained by the simultaneous solution of the continuity equation of flow through a porous medium (derived from a modified version of Darcys law) and the modified Reynolds equation (governing the pressure in the bearing clearance) by the finite difference method (successive over relaxation, central difference) satisfying the appropriate boundary conditions. The effects of journal speed, feeding parameter, supply pressure, porosity parameter and length-to-diameter ratio on the stiffness and damping coefficients have been investigated. A one-dimensional flow model without velocity slip is considered.

Experimental investigation of the stiffness and damping characteristics of aerostatic rectangular thrust bearings

Abstract An experimental test rig was designed and used to determine dynamic characteristics in terms of the stiffness and damping coefficients. A series of experiments was performed on eight variable rectangular orifice-compensated thrust pads. The non-dimensionalized experimental results are presented in the form of design charts for various bearing design parameters.