Influence of Pad Pivot Friction on Tilting-Pad Journal Bearing Measurements—Part I: Steady Operating Position©

Wygant, Karl; Flack, Ronald D.; Barrett, Lloyd

doi:10.1080/10402009908982210

Cited by 22 publications

(8 citation statements)

References 9 publications

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“…It is worth mentioning that one deals with LBP configuration, conventional hydrodynamic lubrication, and clockwise rotational speed (see Figure 2); it means that the journal center moves towards quadrant (III) and (IV) due to a rotor weight load. A very small (almost insignificant) attitude angle can be detected towards quadrants (III), as expected by the hydrodynamic lubrication theory for TPJB [30][31][32] ; ii. System lateral dynamic response at preset journal positions: once the journal reaches its static equilibrium position set by means of the I-controller action within the four bearing quadrants, the rotor-bearing system lateral response is experimentally evaluated in the frequency domain up to 200 Hz.…”

Section: Resultssupporting

confidence: 66%

Exploring integral controllers in actively-lubricated tilting-pad journal bearings

Salazar

Santos

2015

Proceedings of the Institution of Mechanical Engineers, Part J:

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Active tilting-pad journal bearings with radial oil injection combine good stability properties of conventional tilting-pad journal bearings with the capability of improving their dynamic properties even more by control techniques. The main contribution of this work is the experimental investigation of integral controllers for feedback-controlled lubrication with the aim of: a) presetting the static journal center and consequently exploring the changes of bearing dynamic properties; b) obtaining an integral controller capable of re-positioning the static journal eccentricity for matching equilibria under conventional hydrodynamic and feedback-controlled lubrication regimes. A novel application is proposed, that tries to build “non-invasive perturbation forces” and uses the active fluid film forces of the bearing as a “calibrated shaker”.

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Section: Resultssupporting

confidence: 66%

Exploring integral controllers in actively-lubricated tilting-pad journal bearings

Salazar

Santos

2015

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…The pivot radius might be intuitively designed for the pad-pivot friction moment because it is directly related to the amount of the friction moment, as shown in Equation (2). The selected pivot radius ranged from 0.01 m to 0.02 m. As can be seen in Figure 7, a larger pivot radius indicates a higher dynamic eccentricity of the friction-induced instability.…”

Section: Pivot Radiusmentioning

confidence: 99%

“…Various researchers have analyzed the differences in the performance of the two structures. Wygant et al [2,3] conducted a series of experiments to measure the eccentricity ratios, dynamic stiffness, and damping force coefficients of the two types of pivots in the TPJB system. They found variations in the attitude angles and cross-coupled stiffness between the two types of TPJB and concluded that the higher pad-pivot friction in the ball and socket pivot was the primary contributor to the differences.…”

Section: Introductionmentioning

confidence: 99%

Effects of Tilting Pad Journal Bearing Design Parameters on the Pad-Pivot Friction and Nonlinear Rotordynamic Bifurcations

2020

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This study numerically analyzes and investigates the effects of the bearing design parameters of a tilting pad journal bearing (TPJB) on the pad-pivot friction-induced nonlinear rotordynamic phenomena and bifurcations. The bearing parameters were set to the pad preload, pivot offset, spherical pivot radius, and bearing length to diameter (L/D) ratio. The Stribeck curve model (SCM) model was applied at the contact surface between the pad and the pivot, which varied to the boundary-mixed-fluid friction state depending on the friction condition. The rotor-bearing model was set up with a symmetrical five-pad TPJB system supporting a Jeffcott type rigid rotor. The fluid repelling force generated in the oil film between each pad and the shaft was calculated using a finite element method. The simulation recurrently conducted the transient numerical integration to obtain the Poincaré maps and phase states of the journal and pad with various bearing design variables, then the nonlinear properties of each condition were analyzed by expressing the bifurcation diagrams. As a result, the original findings of this study are: (1) The pad preload and pivot offset significantly influenced the emergence of Hopf bifurcations and the associated limit cycles. In contrast, (2) the pivot radius and L/D ratio contributed relatively less to the friction-induced instability. Resultantly, (3) all the effects diminished when the rotor operated under the larger mass eccentricity of the disc.

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“…Petiinato compared the bearing with key seat and spherical seat and showed that the power loss is more speed dependent rather than load dependent [11]. Wygant experimentally studied tilting the pad journal bearing with ball-socket and rockerback style pivots, and found that the friction between pivot and socket will increase the attitude angle, meanwhile increase the cross coupled stiffness [12,13]. Later, he found that the preload had a relative small influence on gas film thickness, eccentricity and attitude angle of the bearing, as well as on the dynamic coefficients indicating high stability [14,15].…”

Section: Introductionmentioning

confidence: 97%

Numerical study on tilting pad journal gas bearing with variable stiffness springs

et al. 2015

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Tilting pad journal gas bearing (TPJGB) with variable stiffness springs has been studied numerically. Elastic shims and displacement restriction component are introduced to realize the function of the variable stiffness springs. With different loads, the compliant component can be modeled as a cantilever beam or a combination of simply supported beam with moment at fixed end. This numerical solution couples the hydrodynamic fluid lubrication Reynolds equation with the deflections of the shims iteratively. The bearing performance with variable stiffness compliant shims has been studied with different bearing numbers. With variable stiffness compliant components, the bearing can provide mild stiffness under light load and higher stiffness under heavier load; the rotor and pad can move coherently. Therefore, the new structure possesses a wider operation range, namely high adaptability.

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Influence of Pad Pivot Friction on Tilting-Pad Journal Bearing Measurements—Part I: Steady Operating Position©

Cited by 22 publications

References 9 publications

Exploring integral controllers in actively-lubricated tilting-pad journal bearings

Exploring integral controllers in actively-lubricated tilting-pad journal bearings

Effects of Tilting Pad Journal Bearing Design Parameters on the Pad-Pivot Friction and Nonlinear Rotordynamic Bifurcations

Numerical study on tilting pad journal gas bearing with variable stiffness springs

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