Prediction of Cavitation in Journal Bearings Using a Boundary Element Method

1995 ◽  
Vol 117 (3) ◽  
pp. 411-421 ◽  
Author(s):  
Qiulin Yu ◽  
Theo G. Keith
Keyword(s):  
Finite Difference ◽  
Boundary Element ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Boundary Integral ◽  
Computational Results ◽  
Film Rupture ◽  
Film Content ◽  
The Finite Difference Method ◽  
Interpolation Polynomials

In this paper, a boundary element cavitation algorithm is utilized to predict cavitation in journal bearings with axially variable clearance. Film rupture and reformation boundary conditions, obtained from the JFO theory, are directly combined with the generalized boundary integral equation which is derived from Elrod’s universal differential equation. The two boundaries are simulated by two confluent interpolation polynomials: The governing equation is transformed into an undetermined boundary problem. The procedure effectively eliminates the phenomenon of solution oscillation experienced by finite difference cavitation algorithms and caused by unadaptable grid shape and density. It also eliminates the discontinuous derivative of the fractional film content. The results for aligned and misaligned journal bearings are compared with those obtained using the finite difference method. Tapered, barrel, and hourglass Journal bearings are also analyzed. The computational results demonstrate the effects of the journal geometric parameters on journal bearing performance.

Analysis of the Dynamic Characteristics of the Aerostatic Journal Bearings

2014 ◽  
Vol 607 ◽  
pp. 600-603
Author(s):  
Chun Dong Xu ◽  
Hui Hui Feng ◽  
Feng Feng Wang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Dynamic Characteristics ◽  
Difference Method ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Damping Coefficients ◽  
Rotation Center ◽  
The Finite Difference Method ◽  
Stiffness And Damping

This paper investigates the dynamic characteristics of the aerostatic journal bearing, the rotation center of which is not the center of the journal length. The Finite Difference Method (FDM) and the perturbation method are employed to calculate the stiffness and damping coefficients. Results show that the coupled stiffness and damping coefficients cannot be neglected due to the rotation center being not the center of the journal length. Furthermore, with the increase of the distance between the rotation center and the center of the journal length, the coupled stiffness and damping coefficients increase.

Analysis of Infinitely Short and Infinitely Long Hydrodynamic Journal Bearings Under Micro-Polar Fluid by Direct Integration Method

2017 ◽  
Author(s):  
Bikash Routh
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Integration Method ◽  
Pressure Profile ◽  
Journal Bearings ◽  
Direct Integration ◽  
Polar Fluid ◽  
Direct Integration Method

In the present paper Reynolds equation of lubrication under micro-polar fluid for journal bearing is solved by direct-integration method under infinitely long and infinitely short journal bearing assumptions [1]. Infinitely long-bearing and infinitely short bearing solutions are the two available approximate closed form solutions for journal bearings. In the present investigation, solution of Reynolds equation i.e. pressure profile is compared with pressure profile obtained by previously used approximate method like finite difference method (FDM). Mentionable here that any approximation method needs lots of calculation and computer programing to get the result. In the present work it has been found that direct-integration method leads the almost same result as the conventionally used complex finite difference method. CFD analysis is also presented in the present work to justify the profile obtained by direct numerical method. It has seen here that theoretical and simulation results are in good agreement to each other’s.

Combined Influence of Misalignment and Orifice Diameter on the Static Performances of Hydrostatic, Water-Lubricated Journal Bearings

2014 ◽  
Vol 607 ◽  
pp. 608-611
Author(s):  
Hui Hui Feng ◽  
Chun Dong Xu ◽  
Feng Feng Wang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Film Thickness ◽  
Power Loss ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Orifice Diameter ◽  
Rigid Rotor ◽  
Static Performance

The water-lubricated bearings have gained an increasing focus to overcome the disadvantages of the oil film bearings and gas bearings. In this paper, the influences of orifice diameter in aligned and misaligned conditions on the static performance of two hydrostatic, four-recess, water-lubricated journal bearings used to support a rigid rotor, are investigated. The steady Reynolds equation for the journal bearing for the turbulent bulk flow and the film thickness expression considering tilting angles are used and numerically solved by finite difference method. Results demonstrate that the static performances, such as the quality, power loss and temperature rise are affected by the tilting angles, orifice diameter to some degree.

scholarly journals Numerical Analysis of a Hydrodynamic Herringbone Grooved Journal Bearing

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
D. Souchet ◽  
A. Senouci ◽  
H. Zaidi ◽  
M. Amirat
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Study ◽  
Hydrodynamic Lubrication ◽  
Dynamical Behavior ◽  
Axial Flow ◽  
Journal Bearings ◽  
Film Rupture ◽  
High Rotational Speed ◽  
Fluid Leakage

In hydrodynamic lubrication, at very high rotational speed, the phenomenon of axial fluid leakage is often present. This can involve an increase of shear stress in the contact and consequently a considerable increase of the temperature. For that and in order to solve this problem, we took interest in the herringbone grooved journal bearings. The researches made before on these types of groove bearing have shown that they present a good dynamical behavior with a low eccentricity and a low axial flow. In this paper, a numerical study of a herringbone journal bearing operating behavior, under laminar and isothermal regime, is presented. The theoretical model, based on the classical Reynolds equation, is used. In order to include the film rupture and reformation, the Reynolds equation is modified using a mass conservative algorithm. To understand the behavior of these herringbone grooved journal bearings well, numerical modeling, using finite element method, has been developed. Various geometrical shapes of the herringbone grooved journal bearings have been analyzed, allowing us to limit the fluid leakage problem, by working particularly on the contact form.

Grid Transformation and Adaption Techniques Applied in the Analysis of Cavitated Journal Bearings

1990 ◽  
Vol 112 (1) ◽  
pp. 52-59 ◽  
Author(s):  
D. Vijayaraghavan ◽  
T. G. Keith
Keyword(s):  
Coordinate System ◽  
Journal Bearing ◽  
Numerical Procedure ◽  
Computer Time ◽  
Journal Bearings ◽  
Second Order ◽  
Film Rupture ◽  
Transformation Procedure ◽  
Grid Adaption ◽  
Induced Flow

An existing cavitation algorithm (a numerical procedure that automatically predicts film rupture and reformation in bearings) is modified in this paper. Second order upwinding is used to difference the shear induced flow terms in the cavitated region. A grid transformation procedure using a body fitted coordinate system and grid adaption techniques are applied to the algorithm. Four statically loaded finite journal bearing cases are analyzed. The results are compared with the results obtained using a conventional grid. The advantage of these methods is demonstrated by obtaining equal or better accuracy with a coarser grid and by the consumption of smaller amounts of computer time.

On the Performance of Journal Bearings Under Conditions of Film Rupture, Part II

1975 ◽  
Vol 97 (4) ◽  
pp. 591-598
Author(s):  
W. A. Crosby ◽  
E. M. Badawy
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Finite Length ◽  
Infinite Number ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Characteristics ◽  
Film Rupture ◽  
Rupture Part

An analytical analysis of journal bearing performance under conditions of film rupture by separation and by cavitation is performed. The ruptured region is considered to have an infinite number of cavities. The boundary condition of Reynolds’ equation at the trailing edge is influenced by the bearing’s operating characteristics and the method of oil admission. A variational solution is given in order to extend the applicability of the boundary conditions to bearings of finite length.

scholarly journals The Prediction of Liquid Film Journal Bearing Performance with a Consideration of Lubricant Film Reformation: Part 1: Theoretical Results

1985 ◽  
Vol 199 (2) ◽  
pp. 95-102 ◽  
Author(s):  
D Dowson ◽  
C M Taylor ◽  
A A S Miranda
Keyword(s):  
Liquid Film ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Lubricant Film ◽  
Supply Rate ◽  
Film Rupture ◽  
Supply Pressure ◽  
Wide Range ◽  
The Reformation ◽  
Theoretical Results

Analyses of liquid film journal bearings rarely consider the reformation of the lubricant film. This reformation normally takes place in the vicinity of a supply groove and is influenced by, amongst other parameters, the lubricant supply pressure. In a previous paper the authors have described in detail the implementation of an algorithm to locate automatically and efficiently the locus of film rupture and reformation boundaries using a digital computer. In the present paper results are presented for a wide range of important variables. In particular, the prediction of lubricant supply rate is studied carefully and compared with data presented in a widely used design aid which does not account in detail for the influence of film reformation.

The Effect of Manufacturing Variations on the Performance of Externally Pressurized Gas-Lubricated Journal Bearings

1985 ◽  
Vol 199 (4) ◽  
pp. 299-309 ◽  
Author(s):  
K J Stout
Keyword(s):  
Finite Difference ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Design Performance ◽  
Finite Difference Technique ◽  
Initial Design ◽  
Performance Predictions ◽  
Gas Bearing ◽  
Experimental Rig

This paper extends the previous work on the hybrid operation of externally pressurized gas bearings to include the effects of manufacturing variations on design performance of the slot entry configuration. Six aspects of manufacture are considered, and include the departure from the design conditions of (a) bearing clearance, (b) feed slot thickness, (c) bearing form, (d) bearing roundness, (e) bearing member alignment, (f) feed slot geometry. Computer predictions of the above effects have been made by introducing modifications to the programs developed to model gas bearing performance developed for solution using a finite difference technique. The results show how the load capacity of the bearings is affected by the departure of dimensions from their design conditions. The magnitude of the departure from the design performance is demonstrated in the figures presented. The performance predictions for the slot entry bearing are compared with results obtained from the orifice compensated journal bearing previously reported. Guidance is given on the limits of departure from initial design conditions which should be allowed for both types of bearing. Confirmation of the accuracy of design predictions has been achieved in this investigation by conducting experiments using test bearings which were very carefully measured to establish the real tolerance on manufacture. These bearings were tested on a specially designed experimental rig.

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