Three-Dimensional Thermohydrodynamic Morton Effect Analysis—Part II: Parametric Studies

Suh, Junho; Palazzolo, Alan

doi:10.1115/1.4027310

Cited by 17 publications

(4 citation statements)

References 8 publications

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“…As can be seen in Figure 5, a "Jeffcott"-type symmetric rigid rotor supported on the five-pad TPJB was employed as a mechanical model to investigate the rotordynamic bifurcation analysis owing to the pad-pivot friction. The governing equations of motion for the rotor and TPJB pads in the system can be written as: (8) where m J and I p are the rotor mass and pad moment of inertia, respectively; and W s and W d are the static and dynamic loads on the rotor, respectively.…”

Section: Rigid Jeffcott Rotor-tpjb Modelmentioning

confidence: 99%

“…The TPJB's stiffness and damping coefficients, which were modified using the equivalent spring model, were in good agreement with the test results, but showed a very large difference in the journal eccentricity. Suh and Palazzolo [8] developed a three-dimensional high fidelity finite element model for the spherical pivot type TPJB, which can simulate the effect of pivot stiffness. They found that the rigid pivot yields the highest temperature in the lubricant, pad, and shaft, providing the increased thermal expansion and the decreased minimum film thickness ratio.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Rigid Jeffcott Rotor-tpjb Modelmentioning

confidence: 99%

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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“…Panara et al [16] found the phenomenon that synchronous vibration instability of overhung rotor due to viscous shearing within lubricant film in engineering. Suh et al [17,18] suggested that there is a large journal surface temperature difference when the journal whirls in journal bearing. It causes temporary rotor thermal bending and leads to vibration instability of the rotor.…”

Section: Introductionmentioning

confidence: 99%

Study on Thermal Unstable Vibration of Rotor under Journal Whirl with Large Amplitude in Journal Bearing

Zhu

Yang

2020

International Journal of Rotating Machinery

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To investigate the thermal unstable vibration caused by journal whirls with large amplitude in journal bearing, an analysis model of lubricant film thickness is established. The journal surface temperature distribution is solved, and the reason for journal surface temperature difference appearance and its influence on rotor vibration are analyzed. Taking a turbogenerator as an example, the journal surface temperature difference and the induced rotor thermal bending under synchronous whirl in the bearing are calculated. Meanwhile, an engineering vibration fault with its treatment is presented. Results show that, the journal surface circumferential temperature difference is caused by viscous shearing within lubricant film under journal whirls with large amplitude in journal bearing. The direction of temperature difference is related to the direction of unbalanced force acting on journal. The temperature difference causes rotor thermal bending, which can be converted to a thermal unbalance on the rotor. The rotor vibration is caused by both thermal and initial unbalance. When the rotor is running below or at the critical speed, the vibration is on the increase until it leads to instability of the rotor eventually. When the rotor is running above the critical speed, the rotor vibration fluctuates periodically. Reducing the initial (mechanical) unbalances decreases the rotor vibration and the journal surface circumferential temperature difference.

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“…Suh J. [5][6] studied the instability of oil film caused by thermal effects. Pouya Asgharifard-Sharabiani [7] presented the nonlinear model identification of oil-lubricated tilting pad bearings.…”

Section: Introductionmentioning

confidence: 99%

Thermo-hydrodynamic Analysis of Journal Hybrid Bearing with Deep/shallow Pockets

Gao¹,

Li²,

Zhu³

2017

dtmse

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This paper presents a theoretical study concerning the oil film pressure distribution, temperature distribution and static characteristics of hybrid journal bearing with deep/shallow pockets. Based on laminar current theory, the coupling equations are established which including Reynolds equation to govern the pressure distribution, energy equation to control the temperature distribution, temperature-viscosity equation and appropriate boundary conditions. The variations of some static characteristics are analyzed under different eccentricity and rotational speed. The result indicates the load carrying capacity, the friction and the volume flow rate all decrease and the attitude angle increase up under thermo-hydrodynamic simulation. These changing trends become more obvious with the rotational speed and the eccentricity ratio rising up.

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Three-Dimensional Thermohydrodynamic Morton Effect Analysis—Part II: Parametric Studies

Cited by 17 publications

References 8 publications

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

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

Study on Thermal Unstable Vibration of Rotor under Journal Whirl with Large Amplitude in Journal Bearing

Thermo-hydrodynamic Analysis of Journal Hybrid Bearing with Deep/shallow Pockets

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