An analytical study of the fluid film force in finite-length journal bearings. Part I

2001 ◽  
Vol 13 (4) ◽  
pp. 329-340 ◽  
Author(s):  
V. D'Agostino ◽  
D. Guida ◽  
A. Ruggiero ◽  
A. Senatore
Keyword(s):  
Finite Length ◽  
Analytical Study ◽  
Journal Bearings ◽  
Fluid Film

Design of Multi-Recess Hydrostatic Journal Bearings for Minimum Total Power Loss

1974 ◽  
Vol 96 (1) ◽  
pp. 226-232 ◽  
Author(s):  
C. Cusano ◽  
T. F. Conry
Keyword(s):  
Rotational Speed ◽  
Power Loss ◽  
Load Capacity ◽  
Maximum Load ◽  
Journal Bearings ◽  
Design Criterion ◽  
Total Power ◽  
Eccentricity Ratio ◽  
Constant Ratio ◽  
Design Charts

The design problem is formulated for multi-recess hydrostatic journal bearings with a design criterion of minimum total power loss. The design is subject to the constraints of constant ratio of the recess area to the total bearing area and maximum load capacity for a given recess geometry. The L/D ratio, eccentricity ratio, ratio of recess area to total bearing area, and shaft rotational speed are considered as parameters. The analysis is based on the bearing model of Raimondi and Boyd [1]. This model is generally valid for low-to-moderate speeds and a ratio of recess area-to-total bearing area of approximately 0.5 or greater. Design charts are presented for bearings having a ratio of recess area-to-total bearing area of 0.6 and employing capillary and orifice restrictors, these being the most common types of compensating elements. A design example is given to illustrate the use of the design charts.

Stability Analysis of Gas-Lubricated, Self-Acting, Plain, Cylindrical, Journal Bearings of Finite Length, Using Galerkin’s Method

1965 ◽  
Vol 87 (1) ◽  
pp. 185-192 ◽  
Author(s):  
H. S. Cheng ◽  
C. H. T. Pan
Keyword(s):  
Stability Analysis ◽  
Finite Length ◽  
Journal Bearings ◽  
Galerkin’S Method ◽  
Galerkin's Method ◽  
Stability Results

This paper extends the method of Cheng and Trumpler [5] to study stability of plain cylindrical gas journal bearings of finite length. Both equilibrium and stability results have been obtained.

A New Analytic Approximation for the Hydrodynamic Forces in Finite-Length Journal Bearings

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Yaser Bastani ◽  
Marcio de Queiroz
Keyword(s):  
Finite Length ◽  
Reynolds Equation ◽  
Computational Study ◽  
Hydrodynamic Forces ◽  
Journal Bearings ◽  
Closed Form Expression ◽  
Impedance Method ◽  
Analytic Approximation ◽  
State Behavior ◽  
Order Polynomial

A new method for determining a closed-form expression for the hydrodynamic forces in finite-length plain journal bearings is introduced. The method is based on applying correction functions to the force models of the infinitely long (IL) or infinitely short (IS) bearing approximation. The correction functions are derived by modeling the ratio between the forces from the numerical integration of the two-dimensional Reynolds equation and the forces from either the IL or IS bearing approximation. Low-order polynomial models, dependent on the eccentricity ratio and aspect ratio, are used for the correction functions. A comparative computational study is presented for the steady-state behavior of the bearing system under static and unbalance loads. The results show the proposed models outperforming the standard limiting approximations as well as a model based on the finite-length impedance method.

Linear stability analysis of finite length journal bearings in laminar and turbulent regimes

2017 ◽  
Vol 231 (10) ◽  
pp. 1254-1267 ◽  
Author(s):  
Mohammad Miraskari ◽  
Farzad Hemmati ◽  
MY Alqaradawi ◽  
Mohamed S Gadala
Keyword(s):  
Linear Stability ◽  
Finite Length ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Stable Region ◽  
Dynamic Coefficients ◽  
Rotor Bearing ◽  
High Reynolds ◽  
Turbulent Models ◽  
Laminar And Turbulent Regimes

Dynamic coefficients of a finite length journal bearing are numerically calculated under laminar and turbulent regimes based on Ng–Pan–Elrod and Constantinescu models. Linear stability charts of a flexible rotor supported on laminar and turbulent journal bearings are found by calculating the threshold speed of instability associated to the start of instable oil whirl phenomenon. Local journal trajectories of the rotor-bearing system were found at different operating conditions solely based on the calculated dynamic coefficients in laminar and turbulent flow. Results show no difference between laminar and turbulent models at low loading while significant change of the size of the stable region was observed by increasing the Reynolds number in turbulent models. Stable margins based on the laminar flow at relatively low Sommerfeld numbers [Formula: see text] were shown to fall inside the unstable region and hence rendering the laminar stability curves obsolete at high Reynolds numbers. Ng-Pan turbulent model was found to be generally more conservative and hence is recommended for rotor-bearing design.

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