The Analysis and Performance of Pivoted Pad Journal Bearings Considering Thermal and Elastic Effects

Ettles, C. M. McC.

doi:10.1115/1.3251465

Cited by 66 publications

(21 citation statements)

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“…Unfortunately, the authors d o not describe the procedure in detail nor d o they present uncertainties. Conlparison of predicted (2) and measured coefficients for multilobe bearings shows fair agreement while cornp;~ring the predicted coefficients for tilting pad bearings (7) to data (6) shows poor to fair agreement.…”

Section: In Cleveland Ohiomentioning

confidence: 76%

Accuracy Evaluation of Experimentally Derived Dynamic Coefficients of Fluid Film Bearings Part I: Development of Method

Kostrzewsky

Flack

1990

Tribology Transactions

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Section: In Cleveland Ohiomentioning

confidence: 76%

Accuracy Evaluation of Experimentally Derived Dynamic Coefficients of Fluid Film Bearings Part I: Development of Method

Kostrzewsky

Flack

1990

Tribology Transactions

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“…Although the offset-halves bearing can be said to have good stability characteristics as judged by a low value of S at the onset of whirl, it appears that the damping in this type of bearing is low. The offset-halves and pivoted-pad journal bearings appear to be similar in this respect (4).…”

Section: Response To Excitationmentioning

confidence: 90%

Journal Bearing Response to Excitation and Behavior in the Unstable Region

Akkök

Ettles

1984

A S L E Transactions

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Three types of journal bearing of circular bore, elliptical, and offset-halves designs were subjected to excitation tests over a wide range of frequency. It is shown that, in the stable region of operation, the amplitude of the response correlates reasonably well with the solutions of linear theory. The response was found to pedk (strongly in some cases) at excitation frequencies i n the range 0.43 to 0.75 of the shaft running speed, depending on design and distance of the operating point from the instability threshold. These observed natural frequencies were found to correlate well with linear theory solutions for lower range frequency values up to about 0.65. At higher predicted natural frequencies, the observed resonance was less than the theoretical solutions.Little is known of bearing behavior beyond the threshold of stability. It is shown experimentally that limit cycle motion occurs in the unstable region. The orbit size can be quite small, depending on preload and other design factors. The orbit size tends to increase with distance from the instability threshold.

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“…The reaction forces computed in Equation 3.1 can be related to dynamic stiffness and damping coefficients by expanding these forces about the static offset position (i.e., the normal operating point) using a Taylor's series expansion [5,13]: 6 For medium-length journal bearings where /4 < UD < 1, n = 2 provides reasonable accuracy [11,14]. .2 constitute the equivalent bearing dynamic coefficients used for dynamic analyses [5].…”

Section: Perturbation Methods For Computing Dynamic Coefficientsmentioning

confidence: 99%

“…Moreover, the computation is sometimes simplified by using "Shelly's Method", which assumes a functional dependence of the pressure in the axial direction [11,14]:…”

Section: Reynolds Equation Solutionmentioning

confidence: 99%

Fluid Film Bearing Dynamic Coefficients and Their Application to Structural Finite Element Models

Campbell¹

2003

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathenng and maintaining the data needed, and completing and reviewing this collection of information Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services. Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204. Arington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2 ABSTRACTA review of methods currently employed for modeling static and dynamic characteristics of fluid film bearings is provided. In nearly all cases, the literature discusses the use of dynamic coefficients for low-order rotor-dynamics models in which a single stiffness and damping matrix is used to connect an individual rotor node to an individual stator/bearing node along the shaft centerline. The focus of the present work is on developing dynamic coefficients for high-order structural finite element models, which use a distribution of the coefficients over the journal circumference. While the methods presented here are applicable to many bearing types, the focus is on the most common bearing, the plain and tilting pad bearing designs. A numerical study is provided to show the importance of properly implementing the bearing coefficients by comparing the results for two methods of coefficient implementation for a rotor model. The results show differences in rotor-to-stator transfer accelerance, resonance frequencies, and damping levels. LIST OF SYMBOLS C = bearing radial clearance C' = pivot point circle clearance F = force G = turbulent correction factor H = characteristic height I = pad rotational inertia L = bearing width M = pad equivalent mass N = number of pads R =journal radius Rp = pad radius Re = Reynolds number = ratio of viscous to inertial forces Re* = modified Reynolds number T = coordinate transformation matrix V = Velocity W = applied load b = damping component e =journal eccentricity h = film thickness k = stiffness component mn = preload p = pressure t = time x = global coordinate in direction of applied load W y = global coordinate in direction perpendicular to x and in bearing plane d2 = angular speed of journal relative to bearing a = angle between pad start and pivot location (measured in +6-direction) e =journal eccentricity ratio = e/C 0 = attitude angle q = local coordinate in direction perpendicular to • y = pad angle . = lubricant kinematic viscosity p = lubricant density 0 = angular coordinate ý = local coordinate passing through pad center of curvature and ...

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The Analysis and Performance of Pivoted Pad Journal Bearings Considering Thermal and Elastic Effects

Cited by 66 publications

References 0 publications

Accuracy Evaluation of Experimentally Derived Dynamic Coefficients of Fluid Film Bearings Part I: Development of Method

Accuracy Evaluation of Experimentally Derived Dynamic Coefficients of Fluid Film Bearings Part I: Development of Method

Journal Bearing Response to Excitation and Behavior in the Unstable Region

Fluid Film Bearing Dynamic Coefficients and Their Application to Structural Finite Element Models

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