Comparison of the characteristics of aerostatic journal bearings considering misalignment under pure-static and hybrid condition

In this paper, the steady-state characteristics, including film pressure, load capacity, stiffness, misalignment moment of aerostatic bearings considering two types of misalignment (along vertical direction [Formula: see text] and along horizontal direction [Formula: see text]) are studied under pure-static and hybrid condition. The journal misalignment effects on the steady-state characteristics under pure-static condition and hybrid condition are studied comparatively. The results show that the load capacity and stiffness increase with the increase in the degree of journal misalignment under hybrid condition, while they decrease with the increase in the degree of journal misalignment under pure-static condition. Moreover, the journal misalignment along two perpendicular direction effects on the performances of aerostatic bearings are also investigated comparatively and the performances of bearing are found to be more sensitive to the misalignment along horizontal direction.

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Research on Turbulent Lubrication of Misaligned Journal Bearing Considering the Axial Motion of Journal

Journal of Tribology ◽

10.1115/1.4045096 ◽

2019 ◽

Vol 142 (2) ◽

Author(s):

Shaoyu Zhu ◽

Jun Sun ◽

Biao Li ◽

Xiaoyong Zhao ◽

Hu Wang ◽

...

Keyword(s):

Load Capacity ◽

Misalignment Angle ◽

Axial Motion ◽

Eccentricity Ratio ◽

Movement Velocity ◽

Film Pressure ◽

Pressure Load ◽

Lubrication Equation ◽

Axial Movement ◽

Journal Misalignment

Abstract Based on the coordinate transformation method, the generalized turbulent lubrication equation considering the axial motion of the journal is derived. The finite-difference method is used to solve the generalized turbulent lubrication equation. The variations of turbulent lubrication performance with axial displacement for different axial movement velocity of the journal, journal misalignment angle, and initial mid-plane eccentricity ratio are obtained. The results show that when the axial movement velocity of the journal increases, the mid-plane eccentricity ratio of the bearing and the minimum film thickness remain unchanged, the average Reynolds number, maximum film pressure, load capacity, frictional power, and side leakage increases. As the axial displacement of the journal increases, the greater the misalignment angle of the journal, the greater the degree of misalignment, maximum film pressure, load capacity, and misalignment moment of the bearing. The greater the initial mid-plane eccentricity ratio, the greater the degree of journal misalignment, maximum film pressure, load capacity, frictional power, and misalignment moment.

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Steady-State and Dynamic Behaviour of Multi-Recess Hybrid Oil Journal Bearings

Journal of Mechanical Engineering Science ◽

10.1243/jmes_jour_1979_021_057_02 ◽

1979 ◽

Vol 21 (5) ◽

pp. 345-351 ◽

Cited By ~ 9

Author(s):

M. K. Ghosh ◽

B. C. Majumdar ◽

J. S. Rao

Keyword(s):

Perturbation Theory ◽

Steady State ◽

Theoretical Analysis ◽

Dynamic Behaviour ◽

Journal Bearing ◽

Load Capacity ◽

Journal Bearings ◽

Time Dependent ◽

Damping Coefficients ◽

Stiffness And Damping

A theoretical analysis of the steady-state and dynamic characteristics of multi-recess hybrid oil journal bearings is presented. A perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term. Load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.

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Effect of Journal Misalignment on the Oil Film Pressure and Temperature Distribution of 3-Lobe Offset Journal Bearing

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-63828 ◽

2005 ◽

Author(s):

S. Strzelecki ◽

Z. Towarek

Keyword(s):

Temperature Distribution ◽

High Speed ◽

Journal Bearing ◽

Journal Bearings ◽

Good Stability ◽

Rotating Machines ◽

Film Pressure ◽

Bearing Design ◽

Journal Misalignment ◽

Oil Film Pressure

The design of turbines and compressors operating at the high rotational speeds applies the 3-lobe journal bearings. In many cases the classic 3-lobe journal bearings supporting the rotors, are showing the problem of rotor stability. This problem can be avoided by the application of 3-lobe Offset bearings. This type of bearing fulfils the conditions of reliable bearing design and good stability in the case of high speed rotating machines.

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Experimentally study of dynamic pressure distribution and oil film forces in journal bearing using ElectroMechanical Film sensor array

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406219884971 ◽

2019 ◽

Vol 234 (4) ◽

pp. 903-913

Author(s):

Changmin Chen ◽

Jianping Jing ◽

Jiqing Cong ◽

Chao Ji

Keyword(s):

Pressure Distribution ◽

Sensor Array ◽

Journal Bearing ◽

Dynamic Pressure ◽

Vertical Direction ◽

Journal Bearings ◽

Film Sensor ◽

Film Pressure ◽

Oil Film ◽

Oil Film Pressure

The acquisition of the oil film pressure and forces on the bearing pads through experimentation is crucial to understanding the characteristics of journal bearing. Lots of efforts had been taken in film pressure measurement, and the pressure was obtained at specified position on the bearing pads. However, due to the space and structure constraint, merely very limited number of the point pressure can be obtained with traditional sensors and acquiring the detail pressure field on whole bearing pad surface is still an open challenge. In this paper, a method based on thin-film sensors technique is proposed and employed to measure the pressure distribution and oil film forces of journal bearings. The measurement is conducted on a cylindrical journal bearing with two axial grooves, and ElectroMechanical Film sensor arrays are designed and laid on the surface of the bearing pads. The oil film pressure is acquired at up to 32 measurement points in total along the bearing pads in both circumference and axial directions. The pressure distribution in a wide rotation speed range is obtained successfully by using fitting algorithm. Furthermore, the oil film forces on horizon and vertical direction are obtained through the integration of the measured pressure filed. The test results prove that it is feasible to measure the oil pressure filed of journal bearings using ElectroMechanical Film piezo-film sensor array.

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Steady-State and Dynamic Analyses of Gas-Lubricated Hybrid Journal Bearings

Journal of Lubrication Technology ◽

10.1115/1.3554850 ◽

1969 ◽

Vol 91 (1) ◽

pp. 171-180 ◽

Cited By ~ 6

Author(s):

W. Shapiro

Keyword(s):

Steady State ◽

Journal Bearing ◽

Load Capacity ◽

External Pressure ◽

Journal Bearings ◽

Preliminary Design ◽

Wide Range ◽

Dynamic Analyses ◽

Flow Charts ◽

Hybrid Bearing

The inherent limitations of load capacity and stability of hydrodynamic gas-lubricated bearings can be reduced by introducing external pressure and creating a hybrid bearing. Numerical computerized analyses of a hybrid journal bearing are discussed; separate developments are presented for steady-state and dynamic characteristics. The steady-state analysis provides performance over a wide range of operating parameters; the more complicated and lengthy dynamic analysis determines stability of the bearing-rotor system using geometry based upon steady-state results. Simplified flow charts of the computer programs are included. The analyses are applied to the preliminary design of a hybrid journal bearing.

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An Improved Short Bearing Analysis for the Submerged Operation of Plain Journal Bearings and Squeeze-Film Dampers

Journal of Lubrication Technology ◽

10.1115/1.3251526 ◽

1980 ◽

Vol 102 (3) ◽

pp. 320-331 ◽

Cited By ~ 5

Author(s):

C. H. T. Pan

Keyword(s):

Load Capacity ◽

Journal Bearings ◽

Squeeze Film ◽

Ambient Fluid ◽

Film Pressure ◽

Squeeze Film Dampers ◽

Natural Boundaries ◽

Orbit Size ◽

Eccentricity Orbit ◽

Bearing Analysis

By allowing the film pressure to assume some subambient value and by allowing natural boundaries of the film to form in the unloaded region, the short-bearing theory of Ocvirk and Dubois is extended to include a detailed description of the cavitation zone. Two alternative cavitation configurations are shown to be possible, rendering different eccentricity (orbit size), attitude angle (phase), for the same load and minimum film pressure. The first configuration features an enclosed cavity maintained at a subambient level and is called “0” cavitation, which is crudely emulated by the conventional “half-film” approximation. The second configuration features ambient level side cavities, the boundaries of which are drawn inside the bearing ends by a sub-cavity film pressure, and is called “I” cavitation. The “I” cavitation, which is initiated by the aggregation of entrained bubbles in the ambient fluid, can present itself in the form of multiple striations causing substantial loss of load capacity.

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A simplified FEM analysis on the static performance of aerostatic journal bearings with orifice restrictor

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650120957132 ◽

2020 ◽

pp. 135065012095713

Author(s):

Hailong Cui ◽

Weiwei Gong ◽

Yueqing Zheng ◽

Yifei Li ◽

Wei Wang ◽

...

Keyword(s):

Elliptic Equation ◽

Pressure Distribution ◽

Load Capacity ◽

Structural Parameters ◽

Fem Analysis ◽

Journal Bearings ◽

Experimental Result ◽

Maximum Relative Error ◽

Film Pressure ◽

Static Performance

This paper puts forward a simplified FEM based on MATLAB PDE tool to investigate the static performance of aerostatic journal bearings. The pressure distribution equation is transformed into a standard elliptic equation, the boundary conditions and coefficients of the transformed equation are also confirmed by contrasting it with the standard elliptic equation. Then the effects of bearings structural parameters and external supply pressure on the film pressure distribution, load capacity and static stiffness are studied. The film pressure distribution changes significantly with the eccentricity ratio, and an eccentricity range corresponding to the optimal stiffness is also confirmed. Finally, an experimental platform with reversal structure is applied to reduce the measurement error, the maximum relative error between the results of simulation and experimental result is 11.54%.

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Misalignment Effect on the Static and Dynamic Characteristics of Hydrodynamic Journal Bearings

Journal of Tribology ◽

10.1115/1.2831542 ◽

1995 ◽

Vol 117 (4) ◽

pp. 717-723 ◽

Cited By ~ 15

Author(s):

Z. L Qiu ◽

A. K. Tieu

Keyword(s):

Dynamic Characteristics ◽

Reynolds Equation ◽

Static Load ◽

Load Capacity ◽

Vertical Direction ◽

Journal Bearings ◽

Static And Dynamic Characteristics ◽

Flow Friction ◽

The Stability ◽

Side Flow

This paper solves the Reynolds equation by the finite difference method in a fixed coordinate system with the static load acted in the vertical direction. All static and dynamic characteristics (including load capacity, attitude angle, side flow, friction force, misaligned moments, and eight linear force coefficients) of a horizontally grooved bearing under different eccentricity and misalignment conditions are presented and compared with available experimental data. The effects of misalignment on all these bearing characteristics and on the stability of the rotor-bearing system are analyzed.

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Effect of non-Newtonian lubrication of squeeze film conical bearing with the porous wall operating with Rabinowitsch fluid model

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650117749735 ◽

2018 ◽

Vol 232 (10) ◽

pp. 1293-1303 ◽

Cited By ~ 2

Author(s):

PS Rao ◽

AK Rahul ◽

S Agarwal

Keyword(s):

Response Time ◽

Reynolds Equation ◽

Graphical Representation ◽

Load Capacity ◽

Porous Wall ◽

Squeeze Film ◽

Film Pressure ◽

Pressure Load ◽

Conical Bearing ◽

Modified Reynolds Equation

In this article, a theoretical study is made to explore the effect of squeezing film in conical bearing for the permeable porous wall utilizing non-Newtonian lubricants. The Permeable medium impacts are characterized by modified Darcy’s law. The modified Reynolds equation representing the non-Newtonian properties following the cubic stress law condition is determined. After general contemplations on the flow in a bearing clearance and in a porous wall, the Cameron approximation is used to acquire modified Reynolds equation. The perturbation technique is used to solve the modified Reynolds equation and closed-form expressions are obtained for the fluid film pressure, load capacity, and response time. The results are illustrated by the graphical representation which shows that the introduction of porous on conical bearing with Rabinowitsch fluid, dilatant lubricant increases the film pressure, load capacity, and response time and decrease for pseudoplastic lubricant as compared to Newtonian fluid.

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A Generalized Solution on the Static Characteristics of Short Hydrodynamic Journal Bearings Using Harmonic Components

Volume 4A: Dynamics, Vibration, and Control ◽

10.1115/imece2016-65509 ◽

2016 ◽

Author(s):

Baisong Yang ◽

Jiale Tian ◽

Jian Zhou ◽

Lie Yu

Keyword(s):

Steady State ◽

Film Thickness ◽

Load Capacity ◽

Harmonic Component ◽

Generalized Solution ◽

Journal Bearings ◽

Hydrodynamic Bearing ◽

Static Performance ◽

Harmonic Components ◽

The Relationship

A theoretical analysis has been done to investigate the static performance of short hydrodynamic journal bearings with a generalized film thickness expression by a sum of Fourier series equation. The hydrodynamic film thickness was written into a summation of an infinite harmonic component of trigonometric function. Reynolds equation with short bearing theory is solved for steady-state operations. In this paper, the steady-state analysis of the generalized hydrodynamic bearing has been done and compared with some typical journal bearings with respect to their harmonic components of film thickness, pressure distribution and load capacity. The relationship between the k-th order harmonic component of the film thickness H0,k and the static pressure component P0,k was established. It was found that the value of P0,k is directly determined not only by the k-th order harmonic component H0,k but also the (k−1)-th order component P0,k−1 indirectly produced by the previous harmonic component H0,k−1.This new investigation method can used to improve the performance of hydrodynamic journal bearings for shape optimization of hydrodynamic journal bearings.

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