Stability Considerations for a Gas-Lubricated Tilting Pad Bearing—Part 2: Analytical Refinements and Stability Data

1972 ◽  
Vol 94 (3) ◽  
pp. 223-233 ◽  
Author(s):  
J. T. McCabe ◽  
T. Y. Chu ◽  
H. G. Elrod
Keyword(s):  
Steady State ◽  
Frequency Response ◽  
Journal Bearing ◽  
Design Data ◽  
Tilting Pad ◽  
Stability Data ◽  
Frequency Response Method ◽  
Response Method ◽  
Tilting Pad Journal Bearing ◽  
Bearing Part

A method for generating the film response of a single gas-lubricated tilting pad journal bearing is derived and it is shown how the results can be used to provide both steady-state and stability data for a three pad bearing. The nature of tilting pad bearing stability is discussed with the aid of frequency response plots, mode shape computations and two illustrative limiting cases. In the first, the bearing pivots are locked and the shaft is free to translate; in the second, the rotor is restrained from translating but the pads are free to pitch. Finally, a design example is given and a comparison is made between a three shoe bearing with design data based on the step-jump method and a four shoe bearing with design data based on the frequency response method.

Stability Considerations for a Gas-Lubricated Tilting-Pad Journal Bearing—Part 1: Analytical Methods

1968 ◽  
Vol 90 (1) ◽  
pp. 162-172 ◽  
Author(s):  
T. Y. Chu ◽  
J. T. McCabe ◽  
H. G. Elrod
Keyword(s):  
Frequency Response ◽  
Journal Bearing ◽  
Response Functions ◽  
Dynamical Equations ◽  
Tilting Pad ◽  
Parametric Studies ◽  
Small Perturbation Method ◽  
Response Method ◽  
Direct Numerical Integration ◽  
Tilting Pad Journal Bearing

The multiplicity of parameters associated with a tilting-pad journal bearing demands that special consideration be given to the selection of an analytical method for stability prediction. The classical Frequency Response (small perturbation) method and the Nonlinear Orbit method (a direct numerical integration of all governing differential equations) are discussed and evaluated. A new approach for the determination of film response called the “Step-Jump” method is here extended to the tilting-pad bearing. Three means of utilizing the film response functions in the dynamical equations are outlined and compared. The relationship of the Frequency Response method to the Step-Jump method is explained and a comparison of the Step-Jump results with the Nonlinear Orbit approach is made. One of the techniques for applying the Step-Jump response functions, called the “Characteristic Equation” method, is shown to be most suitable for parametric studies of stability thresholds.

The Steady-State and Dynamic Characteristics of the Tilting-Pad Journal Bearing in Laminar and Turbulent Flow Regimes

1967 ◽  
Vol 89 (3) ◽  
pp. 392-400 ◽  
Author(s):  
F. K. Orcutt
Keyword(s):  
Steady State ◽  
Turbulent Flow ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Calculated Data ◽  
Operating Parameters ◽  
Experimental Measurements ◽  
Tilting Pad ◽  
Laminar And Turbulent Flow ◽  
Tilting Pad Journal Bearing

Calculated steady-state and dynamic characteristics are given for the four-pad, tilting-pad journal bearing with preload coefficients of 0 and 0.5 and for mean Reynolds up to 12,000. The calculated characteristics are compared with experimental measurements over the same range of operating parameters. Correlation is good, leading to the conclusion that the calculated data are effective for design analysis of rotor-bearing systems using tilting-pad bearings.

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.

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