Design Of Hydrodynamic Journal Bearings Research Articles

Computer-aided design of hydrodynamic journal bearings considering thermal effects

A computer-aided design of hydrodynamic journal bearings is provided considering thermal effects. The Reynolds equation has been solved simultaneously along with the energy equation and heat conduction equations in bush and shaft to obtain the steady-state solution. Using the steady-state solution, a computer-aided design of such bearings is given. In this process, a data bank is generated that consists of load, friction factor and flow rate for different L/D and eccentricity ratios. These data are curve fitted to derive empirical relations for steady-state characteristics. These equations were then used in the design of such bearings. After designing the bearing, stability was checked using a linearized method.

Different magnetic models in the design of hydrodynamic journal bearings lubricated with non-Newtonian ferrofluid

This work is concerned with theoretical study of hydrodynamic journal bearings lubricated with ferrofluids exhibiting non-Newtonian behavior. Based on the momentum and continuity equations for ferrofluid under an applied magnetic field, a modified Reynolds equation has been obtained. Assuming linear behavior for the magnetic material of the ferrofluid, the magnetic force was calculated. The Reynolds equation has been derived to be able to apply to any magnetic field distribution model. Using different magnetic field models, the equation has been solved numerically by the finite-difference technique with appropriate iterative technique and pressure distributions have been obtained. The boundary shape of the load-carrying active regions (positive-pressure regions) and cavitation regions (zero-pressure regions) could be then determined. The solution renders the bearing performance characteristics, namely: load-carrying capacity, attitude angle of the journal center, frictional force at the journal surface, friction coefficient and bearing side leakage. The results indicated that the flow-behavior index has a large effect on the bearing performance. When the bearing operates at high eccentricity ratios, the increase of flow-behavior index gives higher load capacity, lower attitude angle, higher frictional force, lower friction coefficient and higher side leakage. At low eccentricity ratios where the magnetic effects are significant, the effect of the flow-behavior index depends mainly on the magnetic field distribution model used.

Effect of Using Current-Carrying-Wire Models in the Design of Hydrodynamic Journal Bearings Lubricated with Ferrofluid

Based on the momentum and continuity equations for ferrofluid under an applied magnetic field, a modified Reynolds equation has been obtained. Assuming linear behavior for the magnetic material of the ferrofluid, the magnetic force was calculated. The magnetic pressure resulting from the magnetic force was incorporated into the Reynolds equation and it was not separately treated. The derived Reynolds equation can be applied for any magnetic field distribution model. Using different magnetic field models, the equation has been solved numerically by the finite difference technique with an appropriate iterative technique and pressure distributions have been obtained. The boundary shapes of the load-carrying active regions and cavitation regions could be then determined. The solution gives the bearing performance characteristics, namely; load-carrying capacity, attitude angle of the journal center, friction coefficient and bearing side leakage. The displaced current-carrying infinitely long wire gives a field distribution with a gradient in the circumferential direction. Two novel field models are introduced. The concentric finite current-carrying-wire model gives an axially symmetric magnetic field with a gradient in the axial direction. Axial and circumferential gradients are obtained using displaced finite wire model. The effect of these magnetic models and their design parameters on the overall bearing performance characteristics has been studied. The results concluded that the magnetic lubrication provides a higher load capacity and a reduced friction coefficient, compared with a conventional lubricated bearing. The other bearing characteristics depends on the applied field model. An axially symmetric applied field, with its sealing magnetic force, leads to a decrease in the side leakage, such that the bearing may operate without side leakage by appropriate design of the field.

A study of the characteristic analysis of high-speed journal bearings. Optimum design of journal bearings.

This paper describes an optimum design of hydrodynamic journal bearings under laminar and turbulent operating conditions. Simplified closed-form design formulas are presented for the eccentricity ratio, friction force on the journal surface and whirl onset velocity as a function of the Sommerfeld number or eccentricity ratio. The radial clearance, slenderness ratio and viscosity of oil, which optimize both the oil flow rate and the oil film temperature rise in hydrodynamic journal bearings under a constant load, are determined numerically for a wide range of journal revolution speeds.

A study of the characteristic analysis of high speed journal bearings. Optimum design of journal bearings.

This paper describes an optimum design of hydrodynamic journal bearings under laminar and turbulent operating conditions. Simplified mathematical expressions are presented for the eccentricity ratio, friction force and whirl onset speed as a function of the Sommerfeld number or eccentricity ratio. The radial clearance, slenderness ratio and viscosity of lubricants which optimize both the oil flow rate and the oil film temperature rise in hydrodynamic journal bearings under the constant load are determined numerically for a wide range of journal speeds.

The Optimization of Hydrodynamic Journal Bearings for Aerodynamically Excited Flexible Rotor-Bearing Systems

This paper is concerned with the design of hydrodynamic journal bearings to stabilize a large generic class of turbomachinery subjected to aerodynamic excitation. A modal representation of the rotor is used together with a generalized representation of the bearings. This produces a rather simple set of algebraic equations which may be used to determine optimum bearing designs to maximize the level of aerodynamic excitation for stable operation. This approach has proved useful to quickly select bearing designs which warrant more detailed further investigation. A comparison of results obtained from more elaborate and time consuming analysis methods is made. Also an example bearing optimization is given which illustrates one way in which the present analysis method may be used in the design process.

Optimum computerized design of hydrodynamic journal bearings

Solutions of the Reynolds equation have been computed for a bearing configuration which, previously, has received little attention theoretically. Operating characteristics evaluated from the computed solutions are presented graphically, and also form the basis for the development of a computerized optimum design technique. The optimum design objective is stated explicitly in terms of the operating characteristics and is minimised within both design and operative constraints. Optimum designs are given for a range of running conditions for minimum power loss. A comparison is made of the optimum designs obtained for three differing design objectives. Results from the computerised design technique are also compared with the solution given by a long-hand design procedure.

The Optimum Design of Mechanical Systems With Competing Design Objectives

A general method is developed for analyzing optimum design problems with multiple, competing objective junctions. Methods are presented for generating trade-off curves for problems with competing objectives. The usefulness of these methods is demonstrated by applying them to the optimum design of hydrodynamic journal bearings.

Optimum design of hydrodynamic journal bearings: Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 91, Series F, No 3 (1969) pp 516–523

Optimum design of hydrodynamic journal bearings: Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 91, Series F, No 3 (1969) pp 516–523

Optimum design of hydrodynamic journal bearings : A. Seirig and H. Eggat, JOLT, 91, Ser. F, (3) (1969) 516–523; 13 figs., 2 tables, 9 refs.

Optimum design of hydrodynamic journal bearings : A. Seirig and H. Eggat, JOLT, 91, Ser. F, (3) (1969) 516–523; 13 figs., 2 tables, 9 refs.