The Influence of Fluid Inertia on the Dynamic Properties of Journal Bearings

1975 ◽  
Vol 97 (2) ◽  
pp. 159-165 ◽  
Author(s):  
E. Reinhardt ◽  
J. W. Lund
Keyword(s):  
Journal Bearing ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Graphical Form ◽  
Inertial Forces ◽  
Virtual Mass ◽  
Fluid Inertia ◽  
Eccentricity Ratio ◽  
First Order ◽  
First Order Perturbation

Based on a first-order perturbation solution in a modified Reynolds number an analysis is presented to determine the effect of the fluid film inertial forces on the dynamic properties of a journal bearing. The corrections to the regular amplitude and velocity coefficients are found to be small, but the accompanying acceleration coefficients which may correspond to a virtual mass of several times the mass of the journal itself, could become significant for short rotors. Numerical results are given in graphical form with dimensionless coefficients as functions of the operating eccentricity ratio.

Analysis of Pneumatic Instability of Externally Pressurized Porous Gas Journal Bearings

1979 ◽  
Vol 101 (1) ◽  
pp. 48-53 ◽  
Author(s):  
N. S. Rao ◽  
B. C. Majumdar
Keyword(s):  
Theoretical Analysis ◽  
Mass Parameter ◽  
Journal Bearings ◽  
Order Perturbation ◽  
Rigid Rotor ◽  
Eccentricity Ratio ◽  
Dynamic Displacement ◽  
First Order ◽  
Supply Pressure ◽  
First Order Perturbation

A theoretical analysis is presented for the study of pneumatic instability for a rigid rotor supported in externally pressurized porous gas journal bearings. The analysis is based on a first-order perturbation with respect to the amplitude of dynamic displacement of rotor. The variation of threshold mass parameter with feeding parameter is shown. In addition, the effects of supply pressure, eccentricity ratio, L/D ratio, and porosity parameter are investigated and presented in the form of graphs.

The Hybrid Isothermal Air Lubricated Journal Bearing

1979 ◽  
Vol 101 (4) ◽  
pp. 444-450 ◽  
Author(s):  
V. Kamala
Keyword(s):  
Comparative Study ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Order Perturbation ◽  
Load Carrying Capacity ◽  
Eccentricity Ratio ◽  
Small Eccentricity ◽  
First Order ◽  
Load Carrying ◽  
First Order Perturbation

This paper analyzes the load-carrying capacity of the hybrid air lubricated journal bearing. Assuming a small eccentricity ratio, a first order perturbation solution is obtained. The air is fed to the bearing through inherent restrictor with feeding holes distributed around the circumference in one, two, and three feeding planes (Fig. 1). The number of feeding holes in each plane is sufficiently large to permit the feeding planes being treated as the line sources. The results are given for the load-carrying capacity and the attitude angle. A comparative study is made of the three types of gas feeding arrangements.

Externally Pressurized Gas Journal Bearings With Porous Inserts

1980 ◽  
Vol 102 (1) ◽  
pp. 113-116 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Analytical Solution ◽  
Perturbation Method ◽  
Journal Bearings ◽  
Order Perturbation ◽  
Eccentricity Ratio ◽  
First Order ◽  
First Order Perturbation

An analytical solution of externally pressurized gas journal bearings with porous inserts as restrictors is presented. The solution is based on a first-order perturbation method with respect to eccentricity ratio.

A Design of Coverage Area for Textured Surface of Sliding Journal Bearing Based on Genetic Algorithm

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Hui Zhang ◽  
Mahshid Hafezi ◽  
Guangneng Dong ◽  
Yang Liu
Keyword(s):  
Genetic Algorithm ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Textured Surface ◽  
The Novel ◽  
Eccentricity Ratio ◽  
Coverage Area ◽  
Elliptical Shape ◽  
Bearing Load ◽  
Rectangular Grids

This paper aims to improve the tribological performance of journal bearings by optimizing the coverage area of circular microtextures in divergent region of the sleeve. A numerical model is proposed to calculate the friction coefficient and bearing load of textured journal bearings. The surface of the sleeve is divided into rectangular squares. Textures that located at the center of rectangular grids are assumed to be present or absent, marked as 1 and 0, respectively. Afterward, different texture coverage area arrangements are evolved and selected based on the genetic algorithm (GA). The area of semi-elliptical shape is obtained as the novel and preferable textured coverage area design for journal bearings. Influences of width and eccentricity ratio are discussed, which confirm the semimajor and semiminor axes of the semi-elliptical shape of texture coverage area equal to one-third of the circumferential length and half of the width of the journal bearing, respectively.

HYDRODYNAMIC CHARACTERISTICS OF ER FLUID FLOWS IN JOURNAL BEARINGS

2003 ◽  
Vol 17 (01n02) ◽  
pp. 205-208 ◽  
Author(s):  
KE-QIN ZHU ◽  
JIE PENG
Keyword(s):  
Electric Field ◽  
Journal Bearing ◽  
Fluid Flows ◽  
Journal Bearings ◽  
Hydrodynamic Characteristics ◽  
Eccentricity Ratio ◽  
High Eccentricity ◽  
Bingham Plastic ◽  
Er Fluids ◽  
Er Fluid

A numerical analysis is performed on the hydrodynamic characteristics of electrorheological(ER) fluid flows in journal bearings based on the basic hydrodynamic equations. The flow field is assumed to be incompressible and isotropic, the Bingham plastic model is used to describe the behavior of ER fluids. The effect of bearing eccentricity ratio and applied electric field intensity has been studied attentively. It shows that control of the journal bearing through external electric field is much more feasible in high eccentricity ratio bearing than in low eccentricity ratio one.

A Theoretical Analysis of Whirl Instability and Pneumatic Hammer for a Rigid Rotor in Pressurized Gas Journal Bearings

1967 ◽  
Vol 89 (2) ◽  
pp. 154-165 ◽  
Author(s):  
J. W. Lund
Keyword(s):  
Theoretical Analysis ◽  
Time Constant ◽  
Pressure Ratio ◽  
Journal Bearings ◽  
Restricted Feeding ◽  
Rigid Rotor ◽  
Eccentricity Ratio ◽  
Pneumatic Hammer ◽  
Small Eccentricity ◽  
First Order

A theoretical analysis is presented for the threshold of instability for a rigid rotor supported in hydrostatic gas journal bearings. Both rotationally induced instability (hybrid instability) and pneumatic hammer are considered. The analysis is based on a first-order perturbation with respect to the eccentricity ratio (i.e., the results are limited to small eccentricity ratios) and makes use of the linearized Ph-method [2, 5, 8]. The pressurized gas is supplied to the bearing through restricted feeding holes in the center plane of the bearing and the analysis takes into account the discreteness of the feeding holes, the feeder hole time constant, and inherent compensation effects. Numerical results are given in form of 16 graphs, showing the threshold of instability as a function of supply pressure ratio, feeding parameter and eccentricity ratio. Also, the effect of the feeder hole time constant is investigated with respect to pneumatic hammer.

Shaft Center Orbit in Dynamically Loaded Radial Bearings

2005 ◽  
Author(s):  
Peder Klit ◽  
Anders Volund
Keyword(s):  
Journal Bearing ◽  
Classical Method ◽  
First Order ◽  
Damping Coefficients ◽  
Dynamic Coefficients ◽  
Dynamic Damping ◽  
Dynamically Loaded ◽  
Mobility Method ◽  
Coefficient Method ◽  
First Order Perturbation

The bearing damping coefficients may be utilized to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker [1] in 1965. Several authors have refined this method over the years. In 1966 Jorgen W. Lund [2] published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold’s equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. The connection between the “Booker Mobility Method” and the “Lund Damping Coefficient Method” will be explained.

Gas-Lubricated Cylindrical Journal Bearings of the Finite Length: Static Loading

1961 ◽  
Vol 28 (4) ◽  
pp. 535-543 ◽  
Author(s):  
B. Sternlicht
Keyword(s):  
Finite Length ◽  
Static Loading ◽  
Reynolds Equation ◽  
Numerical Solutions ◽  
Journal Bearings ◽  
First Order ◽  
Advantages And Disadvantages ◽  
Iterative Solutions ◽  
Constant Magnitude ◽  
First Order Perturbation

This paper presents numerical solutions of the Reynolds equation for finite length, gas-lubricated cylindrical journal bearings under static loading (this corresponds to a load of constant magnitude and direction with respect to the bearing). It is shown that the incompressible results are but only limiting cases to the more general compressible solutions. The results of the two solutions are dovetailed together through the use of two dimensionless parameters: the inverse of the Sommerfeld number and the compressibility number. Comparisons of the iterative solutions and the first-order perturbation and the “linearized ph” methods are made. The advantages and disadvantages of these methods of analysis are discussed.

Static and Dynamic Properties of Partial Journal Bearings

1963 ◽  
Vol 85 (2) ◽  
pp. 247-255 ◽  
Author(s):  
Paul C. Warner
Keyword(s):  
Differential Equation ◽  
Journal Bearing ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Wide Range ◽  
Governing Differential Equation

The liquid lubricated partial journal bearing is analyzed in an approximate yet accurate manner in order to obtain its static and dynamic properties. The solution of the governing differential equation is analytical rather than numerical, permitting inexpensive computation of results over a very wide range of the parameters involved.

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