Dynamic Characteristics of an Inherently Compensated, Square, Gas Film Bearing

1975 ◽  
Vol 97 (1) ◽  
pp. 52-62 ◽  
Author(s):  
A. K. Stiffler ◽  
D. M. Smith
Keyword(s):  
Numerical Methods ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Dynamic Pressure ◽  
External Pressure ◽  
Periodic Load ◽  
Small Perturbations ◽  
Squeeze Number ◽  
Stiffness And Damping

A rectangular gas film bearing with inherently compensated feedholes evenly distributed around the interior is analyzed. The feedhole boundary between the enclosed central region and the exterior perimeter region is modeled as a line source. A periodic load disturbance is imposed on the externally pressurized bearing, and the dynamic pressure distribution is determined by small perturbations of the Reynolds’ equation. The solution for the square bearing is obtained by numerical methods. Design curves are presented for the load capacity, mass flow, stiffness, and damping as a function of squeeze number, external pressure, restrictor coefficient, and source location. A design methodology is presented.

Analysis of the Stiffness and Damping of an Inherently Compensated, Multiple-Inlet, Circular Thrust Bearing

1974 ◽  
Vol 96 (3) ◽  
pp. 329-336 ◽  
Author(s):  
A. K. Stiffler
Keyword(s):  
Reynolds Equation ◽  
Thrust Bearing ◽  
Dynamic Pressure ◽  
External Pressure ◽  
Periodic Load ◽  
Small Perturbations ◽  
Central Disk ◽  
Squeeze Number ◽  
Stiffness And Damping ◽  
Disk Region

A circular thrust bearing with inherently compensated feedholes evenly distributed around an interior radius is analyzed. The feedhole boundary between the central disk region and exterior annular region is modeled as a line source. A periodic load disturbance is imposed on the bearing, and the dynamic pressure distribution is determined by small perturbations of the Reynolds equation. The solution is given in terms of Kelvin functions. Design curves are presented for the stiffness and damping as a function of squeeze number, external pressure, restrictor coefficient and feedhole location.

Analysis of the Stiffness and Damping Characteristics of an Externally Pressurized Porous Gas Journal Bearing

1977 ◽  
Vol 99 (2) ◽  
pp. 295-301 ◽  
Author(s):  
N. S. Rao
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Dynamic Pressure ◽  
Porous Wall ◽  
Small Perturbations ◽  
One Dimensional ◽  
Damping Characteristics ◽  
Flow Through ◽  
Stiffness And Damping ◽  
Gas Journal Bearing

The dynamic behavior of an externally pressurized porous gas journal bearing is analyzed by assuming one dimensional flow through porous wall. A periodic (displacement) disturbance is imposed on the bearing, and the dynamic pressure distribution is determined by small perturbations of the Reynolds equation. Stiffness and damping for various design conditions are calculated numerically using a digital computer and presented in the form of design charts and tables.

Effect of non-Newtonian magneto-elastohydrodynamic on performance characteristics of slider-bearings

2019 ◽  
Vol 71 (10) ◽  
pp. 1158-1165
Author(s):  
Mouhcine Mouda ◽  
Mohamed Nabhani ◽  
Mohamed El Khlifi
Keyword(s):  
Friction Coefficient ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Transverse Magnetic ◽  
Finite Width ◽  
Two Dimensional ◽  
Content Type ◽  
Slider Bearings ◽  
First Time

Purpose This study aims to examine the magneto-elastohydrodynamic effect on finite-width slider-bearings lubrication using a non-Newtonian lubricant. Design/methodology/approach Based on the magneto-hydrodynamic (MHD) theory and Stokes micro-continuum mechanics, the modified two-dimensional Reynolds equation including bearing deformation was derived. Findings It is found that the bearing deformation diminishes the load-capacity and increases the friction coefficient in comparison with the rigid case. However, the non-Newtonian effect increases load-capacity but decreases the friction coefficient. Moreover, the use of a transverse magnetic field increases both the friction coefficient and load capacity. Originality/value This study combines for the first time MHD and elastic deformation effects on finite-width slider-bearings using a non-Newtonian lubricant.

Squeeze Film Dampers: Amplitude Effects at Low Squeeze Numbers

1975 ◽  
Vol 97 (4) ◽  
pp. 1366-1370 ◽  
Author(s):  
Martin H. Sadd ◽  
A. Kent Stiffler
Keyword(s):  
Reynolds Equation ◽  
Dynamic Performance ◽  
Squeeze Film ◽  
Periodic Disturbance ◽  
Squeeze Film Dampers ◽  
Parallel Surfaces ◽  
Load Characteristics ◽  
Squeeze Number ◽  
Stiffness And Damping ◽  
Film Stiffness

Gaseous squeeze film dampers are analyzed to determine the effect of periodic disturbance amplitude on the dynamic performance. Both circular and rectangular parallel surfaces are investigated. A solution of the nonlinear Reynolds equation is obtained by expanding the pressure in powers of the squeeze number σ, retaining up to and including terms 0(σ2). The time dependent load characteristics are found. The effect of disturbance amplitude on the film stiffness and damping is given.

Dynamic Stiffness and Damping Coefficients of Aerostatic, Porous, Journal Bearings

1978 ◽  
Vol 20 (5) ◽  
pp. 291-296 ◽  
Author(s):  
N. S. Rao ◽  
B. C. Majumdar
Keyword(s):  
Continuity Equation ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Dynamic Pressure ◽  
Dynamic Stiffness ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Damping Coefficients ◽  
Design Charts ◽  
Stiffness And Damping

A periodic (displacement) disturbance is imposed on an aerostatic, porous, journal bearing of finite length under steady-state conditions. The dynamic pressure distribution is obtained by a pressure perturbation analysis of Reynolds equation and a modified flow continuity equation in a porous medium. Dynamic stiffness and damping coefficients for different operating conditions are calculated numerically, using a digital computer, and presented in the form of design charts.

Limiting Stiffness and Damping Coefficients of Foil Bearing

2005 ◽  
Author(s):  
Jerzy T. Sawicki ◽  
T. V. V. L. N. Rao
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Necessary Conditions ◽  
Load Capacity ◽  
Damping Coefficients ◽  
Foil Bearing ◽  
Infinitesimal Perturbation ◽  
Stiffness And Damping ◽  
Limiting Values ◽  
Gas Journal Bearing

The limiting values of load capacity, stiffness and damping coefficients for a foil bearing are presented. The necessary conditions for high bearing numbers (journal operating at high speed) are obtained by simplifying the compressible Reynolds equation. Linearized stiffness and damping coefficients are obtained using infinitesimal perturbation method. Results of load capacity, stiffness and damping coefficients, for foil bearing are compared with those obtained for a rigid gas journal bearing. The limiting values of dynamic characteristics for a foil bearing are constant for all eccentricity ratios.

scholarly journals Spherical Squeeze-Film Hybrid Bearing With Small Steady-State Radial Displacement

1967 ◽  
Vol 89 (3) ◽  
pp. 254-262 ◽  
Author(s):  
T. Chiang ◽  
S. B. Malanoski ◽  
C. H. T. Pan
Keyword(s):  
Asymptotic Approximation ◽  
Axial Load ◽  
Radial Displacement ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Squeeze Film ◽  
Axial Stiffness ◽  
Axial Load Capacity ◽  
Hybrid Bearing ◽  
Squeeze Number

Spherical squeeze-film hybrid bearings were analyzed theoretically. Based on an asymptotic approximation for large squeeze number, the solution of the Reynolds’ equation applicable to the system under investigation was obtained. Perturbation method has been used; the results are valid for small radial displacement only. It has no limitation, however, in the values of compressibility number, axial displacement ratio, and excursion ratio. Numerical calculations have been programmed on the GE205 computer. Axial load capacity, axial stiffness, and radial and tangential stiffnesses were obtained.

Performance and Stability of a Hybrid Spherical Gas Gyrobearing

1991 ◽  
Vol 113 (3) ◽  
pp. 458-463 ◽  
Author(s):  
N. M. Sela ◽  
J. J. Blech
Keyword(s):  
Equilibrium Point ◽  
Dynamic Stability ◽  
Flow Rate ◽  
Gas Flow ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Equations Of Motion ◽  
Gas Flow Rate ◽  
Small Perturbations ◽  
Static Performance

A new spherical Gas Gyrobearing configuration is presented. The static performance is evaluated for general eccentricity, and data is presented for load capacity, gas flow rate and error torque, over a range of eccentricities and gas feed pressures. The dynamic stability of the rotor about an equilibrium point, assuming small perturbations, is analyzed using the step-jump method. Finally, a nonlinear path simulation was performed, by simultaneously solving the Reynolds equation and the rotor’s equations of motion.

On the Dynamics of Elastohydrodynamic Mixed Lubricated Ball Bearings. Part I: Formulation of Stiffness and Damping Coefficients

2005 ◽  
Vol 219 (6) ◽  
pp. 411-421 ◽  
Author(s):  
M Sarangi ◽  
B. C. Majumdar ◽  
A. S. Sekhar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Design Parameters ◽  
Asperity Contact ◽  
Damping Coefficients ◽  
Damping Characteristics ◽  
Stiffness And Damping

The problems of stiffness and damping characteristics of isothermal elastohydrodynamic mixed lubricated point contact are evaluated numerically considering surface roughness effect including asperity contact load. A set of equations under steady-state and dynamic conditions is derived from the classical Reynolds equation, using linear perturbation method. The elasticity equation and steady-state Reynolds equation are solved simultaneously for finding the steady-state pressure distribution, using finite difference method. Then, the set of perturbed equations is solved for the dynamic pressure distribution in the contact. A Gaussian surface roughness is adopted to model both surface roughness and mixed lubrication. Total load capacity of the contact is calculated from the lubricant film pressure and contact pressure distribution. Results are compared with those of smooth isothermal cases. The stiffness and damping coefficients of the contact are determined using the dynamic pressures. The asperity contact stiffness is calculated separately. Effect of various design parameters on stiffness and damping characteristics of a ball bearing is investigated.

Dynamic characteristics of opposed-conical gas-dynamic bearings

2019 ◽  
Vol 72 (3) ◽  
pp. 415-425 ◽  
Author(s):  
Yan Li ◽  
Desheng Zhang ◽  
Fuhai Duan
Keyword(s):  
Dynamic Characteristics ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Critical Mass ◽  
Degree Of Freedom ◽  
Content Type ◽  
Damping Coefficients ◽  
Gas Dynamic ◽  
The Stability ◽  
Stiffness And Damping

Purpose The purpose of this paper is to investigate dynamic characteristics of opposed-conical gas-dynamic bearings considering five degree-of-freedom motion, including translation and tilt. Design/methodology/approach The steady-state Reynolds equation and perturbed Reynolds equations are solved on the surface of conical bearings, and both stiffness and damping coefficients are calculated. A formula for quickly calculating critical mass is deduced to discriminate the stability of the rotor considering the five degree-of-freedom motion. Findings Results show that the stability of the rotor is mainly determined by translation rather than tilt. The formula of critical mass is validated by comparing the results with traditional Routh–Hurwitz criterion. Originality/value The formula proposed in this paper greatly simplifies the solution of critical mass, which facilitates the rotor stability design. It is applicable for opposed-conical bearings, opposed-hemispherical bearings and spherical bearings. The results provide theoretical guidance for the design of gas-dynamic bearings.

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