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You searched for subject:(dynamic bearing coefficients). Showing records 1 – 2 of 2 total matches.

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Texas A&M University

1. Al-Ghasem, Adnan Mahmoud. Measurement of rotordynamic coefficients for a high-speed flexure pivot tilting-pad bearing(load between pad) configuration.

Degree: 2005, Texas A&M University

This thesis presents the dynamic and static forced performance of a flexure-pivot tilting-pad bearing load between pad (LBP) configuration for different rotor speeds and bearing unit loadings. The bearing has the following design parameters: 4 pads with pad arc angle 72o and 50% pivot offset, pad axial length 0.0762 m (3 in), pad radial clearance 0.254 mm (0.010 in), bearing radial clearance 0.1905 mm (0.0075 in), preload 0.25 and shaft nominal diameter of 0.11684 m (4.600 in). The dynamic coefficients and the static performance parameters of the FPB have been compared with the theoretical predictions using the isothermal analysis from the rotordynamic software suite XLTRC2-XLTFPBrg. The bearing shows a small attitude angle, about 10o, which indicates small crosscoupling stiffnesses. The pad temperatures increase in the circumferential direction of rotation with speed and load. The pads maximum temperature was measured near the trailing edge. The dependency of the stiffness and damping coefficients on the excitation frequency has been studied. The frequency dependency in the dynamic coefficients was removed by introducing an added mass coefficient to the bearing model. The direct added mass coefficients were around 32 kg. The direct stiffness and damping coefficients increase with load, while increasing and decreasing with rotor speed, respectively. A small whirl frequency ratio (WFR) was found of about 0.15, and it decreases with load and increases with speed. A comparison between the dynamic stiffnesses using a Reynolds equation and the bulk-flow Navier-Stokes models with the experimental dynamic stiffnesses shows that the Reynolds model (even for laminar flows) is not adequate, and that the bulk-flow model should be used for rotordynamic coefficients prediction. The bulk-flow model in general predicts well the static performance parameters and the direct dynamic coefficients, and underpredicts the cross-coupled coefficients (overpredicts the stability). Advisors/Committee Members: Childs, Dara W..

Subjects/Keywords: Flexure-pivot; Tilting Pad Bearing; Dynamic Coefficients; Pad Temperature; frequency dependency

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Al-Ghasem, A. M. (2005). Measurement of rotordynamic coefficients for a high-speed flexure pivot tilting-pad bearing(load between pad) configuration. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/2415

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Al-Ghasem, Adnan Mahmoud. “Measurement of rotordynamic coefficients for a high-speed flexure pivot tilting-pad bearing(load between pad) configuration.” 2005. Thesis, Texas A&M University. Accessed August 05, 2020. http://hdl.handle.net/1969.1/2415.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Al-Ghasem, Adnan Mahmoud. “Measurement of rotordynamic coefficients for a high-speed flexure pivot tilting-pad bearing(load between pad) configuration.” 2005. Web. 05 Aug 2020.

Vancouver:

Al-Ghasem AM. Measurement of rotordynamic coefficients for a high-speed flexure pivot tilting-pad bearing(load between pad) configuration. [Internet] [Thesis]. Texas A&M University; 2005. [cited 2020 Aug 05]. Available from: http://hdl.handle.net/1969.1/2415.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Al-Ghasem AM. Measurement of rotordynamic coefficients for a high-speed flexure pivot tilting-pad bearing(load between pad) configuration. [Thesis]. Texas A&M University; 2005. Available from: http://hdl.handle.net/1969.1/2415

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Gyurko, John Harrison. Experimental Determination of the Distributed Dynamic Coefficients for a Hydrodynamic Fluid Film Bearing.

Degree: PhD, Acoustics, 2013, Penn State University

Most current rotor bearing analysis utilizes lumped parameter bearing coefficients to model the static and dynamic characteristics of fluid film bearings. By treating the stiffness and damping properties of the fluid film as acting upon the axial centerline of the rotor, these models are limited in their analysis to first order lateral rotor-bearing motion. The development of numerical methods that distribute the dynamic properties of the fluid film around the bearing circumference allow for higher order analysis of the motion between the bearing and rotor. Assessment of the accuracy of the numerical method used to calculate distributed dynamic fluid film bearing coefficients is performed by developing a novel hydrodynamic journal bearing test rig and experimental testing procedure capable of obtaining measured distributed dynamic coefficients over a range of bearing operating conditions. The instrumented bearing test rig is used to measure the dynamic bearing displacement and fluid film pressure responses from application of an externally applied excitation force. Least squares solution to a system of perturbated pressure equations, populated by measured displacement and pressure responses, is used to determine the hydrodynamic stiffness and damping properties for a finite region of the bearing surface. Incremental rotation of pressure sensors embedded in the body of the test bearing allow for measurement of the fluid film circumferential pressure distribution which is used to calculate a set of experimentally determined dynamic bearing coefficients. Distributed bearing coefficients derived from experimental measurements are compared to numerically calculated distributed coefficients as well as to lumped parameter coefficients generated from experimental and numerical methods found in the literature. Overall, the numerically calculated distributed coefficients successfully model both the circumferential distribution and the operating conditions of the experimental distributed bearing coefficient values and show reasonable correlation to results obtained through lumped parameter methods. Excitation frequency independence is validated through experimental testing over multiple frequencies, and damping cross term inequality of the numerically distributed bearing coefficients is validated by lumped coefficient analysis found in the literature. While uncertainty and variation of the test rig dimensional and operating parameters have some effect on the accuracy with which the numerical methods model the experimental results, the most significant source of dissimilarity in numerical and experimental results comes from test rig specific features not captured in the numerical methods, such as bearing surface wear and bearing-shaft misalignment.

Subjects/Keywords: hydrodynamic lubrication; experimental test rig; fluid film bearing; dynamic bearing coefficients; circumferential distribution

…101 Figure 4-16. Distributed dynamic bearing stiffness coefficients for a Sommerfeld number… …103 Figure 4-17. Distributed dynamic bearing damping coefficients for a Sommerfeld number of… …104 Figure 4-18. Distributed dynamic bearing stiffness coefficients for a Sommerfeld number… …105 Figure 4-19. Distributed dynamic bearing damping coefficients for a Sommerfeld number of… …106 Figure 4-20. Distributed dynamic bearing stiffness coefficients for a Sommerfeld number… 

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gyurko, J. H. (2013). Experimental Determination of the Distributed Dynamic Coefficients for a Hydrodynamic Fluid Film Bearing. (Doctoral Dissertation). Penn State University. Retrieved from https://etda.libraries.psu.edu/catalog/18878

Chicago Manual of Style (16th Edition):

Gyurko, John Harrison. “Experimental Determination of the Distributed Dynamic Coefficients for a Hydrodynamic Fluid Film Bearing.” 2013. Doctoral Dissertation, Penn State University. Accessed August 05, 2020. https://etda.libraries.psu.edu/catalog/18878.

MLA Handbook (7th Edition):

Gyurko, John Harrison. “Experimental Determination of the Distributed Dynamic Coefficients for a Hydrodynamic Fluid Film Bearing.” 2013. Web. 05 Aug 2020.

Vancouver:

Gyurko JH. Experimental Determination of the Distributed Dynamic Coefficients for a Hydrodynamic Fluid Film Bearing. [Internet] [Doctoral dissertation]. Penn State University; 2013. [cited 2020 Aug 05]. Available from: https://etda.libraries.psu.edu/catalog/18878.

Council of Science Editors:

Gyurko JH. Experimental Determination of the Distributed Dynamic Coefficients for a Hydrodynamic Fluid Film Bearing. [Doctoral Dissertation]. Penn State University; 2013. Available from: https://etda.libraries.psu.edu/catalog/18878

.