A Waved Journal Bearing Concept-Evaluating Steady-State and Dynamic Performance With a Potential Active Control Alternative

1993 ◽  
Author(s):  
Florin Dimofte
Keyword(s):  
Steady State ◽  
Wave Amplitude ◽  
Journal Bearing ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Film Stability ◽  
Dynamic Coefficients ◽  
The Waves ◽  
Compressible Lubricant

Abstract Analysis of the waved journal bearing concept featuring a waved inner bearing diameter for use with a compressible lubricant (gas) is presented. The performance of generic waved bearings having either three or four waves is predicted for air lubricated bearings. Steady-state performance is discussed in terms of bearing load capacity, while the dynamic performance is discussed in terms of fluid film stability and dynamic coefficients. It was found that the bearing wave amplitude has an important influence on both steady-state and dynamic performance of the waved journal bearing. For a fixed eccentricity ratio, the bearing steady-state load capacity and direct dynamic stiffness coefficient increase as the wave amplitude increases. Also, the waved bearing becomes more stable as the wave amplitude increases. In addition, increasing the number of waves (e.g., four waves instead of three waves) reduces the waved bearing’s sensitivity to the direction of the applied load relative to the wave. However, the range in which the bearing performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the waved bearing design for a specific application. Another possibility is to use the waved bearing to actively control the rotor-bearing system dynamic coefficients via actively controlling the wave amplitude.

A Comparison of the Steady-State and Dynamic Performance of First- and Second-Generation Foil Bearings

2010 ◽  
Author(s):  
M. J. Conlon ◽  
A. Dadouche ◽  
W. M. Dmochowski ◽  
R. Payette ◽  
J.-P. Be´dard
Keyword(s):  
Steady State ◽  
Experimental Evaluation ◽  
First Generation ◽  
Second Generation ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Stiffness And Damping

Oil-free foil bearing technology has advanced intermittently over the years, driven by research efforts to improve both steady-state and dynamic performance characteristics, namely: load capacity, stiffness, and damping. Bearing designs are thus classified according to “generation”, with first-generation bearings being the most primitive. This paper presents an experimental evaluation of a first- and a second-generation foil bearing, and aims to provide the high-fidelity data necessary for proper validation of theoretical predictive models of foil bearing performance. The aforementioned test bearings were fabricated in-house, and are both 70mm in diameter with an aspect ratio of 1; bearing manufacturing details are provided. The work makes use of a facility dedicated to measuring both the steady-state and dynamic properties of foil bearings under a variety of controlled operating conditions. The bearing under test is placed at the midspan of a horizontal, simply-supported, stepped shaft which rotates at up to 60krpm. Static and dynamic loads of up to 3500N and 450N (respectively) can be applied by means of a pneumatic cylinder and two electrodynamic shakers. The bearings’ structural (static) stiffnesses are highly nonlinear, and this affects the accuracy of the dynamic coefficient determination. Both dynamic stiffness and damping are found to vary nonlinearly with excitation frequency, and are over-predicted by a structural experimental evaluation — the film plays an important role in bearing dynamics. The second-generation bearing is found to have a higher load capacity, dynamic stiffness, and damping than the first-generation bearing.

The Influence of Pad Pivot Elastic Deformation on Static and Dynamic Coefficients for Fixed-Tilting Pad Journal Bearing

2017 ◽  
Author(s):  
Tian Jiale ◽  
Yang Baisong ◽  
Sun Yanhua ◽  
Yu Lie ◽  
Zhou Jian
Keyword(s):  
Elastic Deformation ◽  
High Speed ◽  
Journal Bearing ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Oil Film ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Two Factors ◽  
Tilting Pad Journal Bearing

High-speed and heavy-loaded rotating machinery require accurate prediction of rotor’s response and stability, which can be characterized by the static and dynamic coefficients of the bearing support. In this paper, a theoretical study has been done to investigate the performance of a fixed-tilting pad journal bearing with ball-in-socket pivot. The analytical model is established with the flexibility of the pad pivot and turbulent effect of the oil film both taken consideration. Under such situation, the pad pivot elastic deformation and its stiffness are calculated using Hertz Contact Theory for various operating points of the rotor-bearing system. The finite element method is adopted to simulate the static coefficients of the fixed-tilting pad bearing, obtaining its oil film pressure distribution varied with the bearing eccentricity ratio. The corresponding dynamic stiffness and damping of the oil film are solved using partial derivative method. In addition, a special interest is put in investigating the effect of the series complex stiffness of the oil film and pad pivot, according to which, the equivalent dynamic characteristics are obtained. The results show that the relation between these two factors are complex and interactive, both of which have a significant influence on the static and dynamic performance of the bearing.

Numerical analysis of the dynamic performance of aerostatic thrust bearings with different restrictors

2018 ◽  
Vol 233 (3) ◽  
pp. 406-423 ◽  
Author(s):  
Hailong Cui ◽  
Yang Wang ◽  
Xiaobin Yue ◽  
Yifei Li ◽  
Zhengyi Jiang
Keyword(s):  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Dynamic Mesh ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
The Impact ◽  
The Relationship

This study utilizes a dynamic mesh technology to investigate the dynamic performance of aerostatic thrust bearings with orifice restrictor, multiple restrictors, and porous restrictor. An experiment, which investigates the bearing static load capacity, was carried out to verify the calculation accuracy of dynamic mesh technology. Further, the impact of incentive amplitude, incentive frequency, axial eccentricity ratio, and non-flatness on the bearing dynamic performance was also studied. The results show incentive amplitude effect can be ignored at the condition of amplitude less than 5% film thickness, while the relationship between dynamic characteristics and incentive frequency presented a strong nonlinear relationship in the whole frequency range. The change law of dynamic stiffness and damping coefficient for porous restrictor was quite different from orifice restrictor and multiple restrictors. The bearing dynamic performance increased significantly with the growth of axial eccentricity ratio, and the surface non-flatness enhanced dynamic performance of aerostatic thrust bearings.

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

1979 ◽  
Vol 21 (5) ◽  
pp. 345-351 ◽  
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.

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

1969 ◽  
Vol 91 (1) ◽  
pp. 171-180 ◽  
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.

Analysis of dynamic characteristics of spiral groove liquid film seal under thermal–fluid–solid coupling

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bo Yu ◽  
Muming Hao ◽  
Sun Xinhui ◽  
Zengli Wang ◽  
Liu Fuyu ◽  
...  
Keyword(s):  
Steady State ◽  
Liquid Film ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Analysis Model ◽  
Spiral Groove ◽  
Content Type ◽  
Sealing Performance ◽  
Stiffness And Damping

Purpose The purpose of this paper is to investigate the dynamic characteristics of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling. Design/methodology/approach The dynamic analysis model of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling was established by perturbation method. The steady-state and perturbation Reynolds equations were solved, and the steady-state sealing performance and dynamic characteristic coefficients of the liquid film were obtained. Findings Compared with the liquid film without coupling method, a divergent seal gap is formed between the seal rings under the effect of thermal–fluid–solid coupling, the minimum liquid film thickness decreases, the dynamic stiffness and damping coefficients of the liquid film are increased and the thermoelastic deformation of the end-face improves the dynamic performance of the liquid film seal. Originality/value The dynamic characteristics of the spiral groove liquid film seal under the effect of thermal–fluid–solid coupling are studied, which provides a theoretical reference for optimizing the dynamic performance of the non-contacting liquid film seal.

Identification of dynamic coefficients of the journal bearing considering velocity slip of cavitation zone in the rotating spindle unit

2018 ◽  
Vol 232 (10) ◽  
pp. 1304-1317
Author(s):  
Feng Cheng ◽  
Weixi Ji
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Identification Accuracy ◽  
Identification Algorithm ◽  
Dynamic Coefficients ◽  
Displacement Error ◽  
Spindle Unit ◽  
Cavitation Erosion Resistance

A rotating spindle unit, supported by the journal bearings, is developed to improve the cavitation erosion resistance of the journal bearing as well as the spindle dynamic performance. The turbulent lubrication model considering velocity slip in cavitation zone is derived, and the static and dynamic parameters of the journal bearing are obtained. An identification algorithm is further derivated to identify simultaneously the 16 dynamic coefficients of the two journal bearings in the spindle unit. The available experimental results reveal that the journal bearing coefficients are well predicted and estimated by the present model, and the estimated bearing parameters by regularization solution are in good agreement with the assumed values, while it has opposite effect by directed solution for discrete ill-posed problems. It is concluded that the identification accuracy of bearing parameters is governed by the displacement error, and the percentage deviation of dynamic coefficients decreases with the decrease of the displacement error.

Study on Load Capacity and Dynamic Characteristics of the Wave Bearing at Infinite Compressibility Number

2014 ◽  
Author(s):  
Baisong Yang ◽  
Haipeng Geng ◽  
Jian Zhou ◽  
Lie Yu ◽  
Shemiao Qi ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Journal Bearing ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Computational Method ◽  
Wave Number ◽  
Algebraic Equations ◽  
Eccentricity Ratio ◽  
Operation Speed ◽  
Stiffness And Damping

The wave bearing developed by Dimofte in the 1990’s features a continuous wave profile and presents numerous advantages compared to plain journal bearings. One of the main advantages of the wave bearing is that it has a higher degree of stability than the plain journal bearing and this load capacity is close to the load capacity of the plain journal bearing. Predicting these coefficients for the wave bearing with high bearing numbers is difficult, although there are many studies on the aerodynamic bearing. This paper presents an analytical method for calculating the limiting values of load capacity, dynamic stiffness and damping coefficients of the wave bearing for compressible fluids by simplifying the compressible Reynolds equation at high journal operation speed. A computational method is submitted which is derived from simple algebraic equations combined with infinitesimal perturbation method. The limiting characters of the wave bearing are compared with the plain journal bearing for all eccentricity ratios. Special emphasis is placed on investigating the effects of wave number, wave eccentricity ratio and wave starting angle on the limiting characteristics. Numerical results obtained indicate that the load capacity and stiffness of the wave bearing is better than the plain journal bearing at the same eccentricity ratio.

scholarly journals A CFD-Based Frequency Response Method Applied in the Determination of Dynamic Coefficients of Hydrodynamic Bearings. Part 1: Theory

Lubricants ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 23 ◽  
Author(s):  
Troy Snyder ◽  
Minel Braun
Keyword(s):  
Frequency Response ◽  
Journal Bearing ◽  
Dynamic Stiffness ◽  
Added Mass ◽  
Operating Conditions ◽  
Slider Bearing ◽  
Hydrodynamic Bearings ◽  
Dynamic Coefficients ◽  
Frequency Response Method ◽  
Response Method

A general, CFD-based frequency response method for obtaining the dynamic coefficients of hydrodynamic bearings is presented. The method is grounded in experimental parameter identification methods and is verified for an extremely long, slider bearing geometry as well as short and long journal bearing geometries. The influence of temporal inertia on the dynamic response of the bearings is discussed and quantified through the inclusion of added mass coefficients within the mechanical models of the hydrodynamic bearing films. Methods to separate the dynamic stiffness into static stiffness and added mass contributions are presented and their results compared. Harmonic perturbations are applied to the bearings at varying frequencies to determine the frequency dependence of the dynamic coefficients and to facilitate the decomposition of the dynamic stiffness into its constituents. Added mass effects are shown to be significant for the extremely long slider bearing geometry and negligible for the short and long journal bearing geometries under operating conditions motivated by those typical of marine bearings.

Mechanical and Electrical Run-Out Removal on a Precision Rotor-Vibration Research Spindle

1997 ◽  
Vol 119 (2) ◽  
pp. 216-220 ◽  
Author(s):  
G. A. Horattas ◽  
M. L. Adams ◽  
F. Dimofte
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Journal Bearing ◽  
Dynamic Performance ◽  
Data Acquisition System ◽  
Small Range ◽  
Rotor Vibration ◽  
System 1 ◽  
Better Than

Experimental determination of both steady-state and dynamic performance of a journal bearing requires the use of a high precision spindle with a vanishingly small range of run-out. This was achieved by first eliminating the mechanical run-out of the spindle by grinding the journal specimen while rotating in place. Once the mechanical run-out was removed, the electrical run-out sensed by the displacement proximity-probe-transducers was also removed. Using this procedure the mechanical and electrical run-outs of a research spindle were reduced to less than 0.2 micron (10 μin.), which is better than the resolution of the data acquisition system, 1 micron (50 μin.).

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