• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.499-500
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• 2007

• Tribology and Lubricants
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• v.13 no.3
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• pp.33-41
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• 1997

In this paper the linearized stiffness and damping coefficients of tilting pad thrust bearing are calculated by the perturbation method. The coefficients are obtained for a wide range of pivot positions. The effects of exciting frequency and pad mass on stiffness and damping coefficients are investigated. Critical frequencies due to the tilting motions of the pad are presented and are shown to be strongly influenced by the pivot position and the pad mass.

• Tribology and Lubricants
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• v.14 no.1
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• pp.7-13
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• 1998

The static characteristics of a five-pad tilting pad journal bearing of load on pad (LOP) type have been investigated experimentally under the different values of bearing load and shaft speed. The diameter and length of the bearing are 300.91 mrn and 149.8 mm, reslx;ctively. Circumferential distribution of the film pressure, film thickness, journal surface temperature and beating surface temperature are measured. A noticeable inlet pressure rise is observed at the entrance of each pad, especially the bottom pad. The inlet pressure is increased by the increase of shaft speed as well as bearing load. In the five-pad tilting pad joumal bearing of LOP type, almost all of beating load is being carried only by the bottom pad. The maximum bearing surface temperature is observed at near the minimum film thickness. It is observed that the metal temperature of the mid-plane is higher than that of the edge at the inlet region, while the metal temperature of the edge is higher than that of the mid-plane at the outlet region.

• Tribology and Lubricants
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• v.18 no.5
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• pp.357-363
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• 2002

The vibration characteristics of the pad fluttering in a fluid film tilting pad journal bearing (4-pad LBP) have been investigated experimentally under the different values of oil supply flow rate, bearing load and shaft speed. The vibration characteristics of the pad fluttering are estimated by measuring the time signal of circumferential distribution of the film thickness and the cascade plot of the response of the relative displacement between the bearing and the shaft. It is shown that the vibration frequency of the pad fluttering has a sub-synchronous frequency and almost does not change by the increase of shaft speed. However the vibration amplitude is increased by the increase of shaft speed. From those experimental results, pad fluttering can be thought of as a self-excited vibration. The incipient pad fluttering velocity is increased by the increase of oil supply flow rate and by the decrease of bearing load. It is observed that the vibration amplitude of the pad fluttering can be decrease by the control of supply oil flow rate effectively. And also It is known that the outbreak of pad fluttering does not concern with the shaft vibration.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.228-234
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• 2000

The vibration characteristics of the pad fluttering in a fluid film tilting pad journal bearing(4-pad LBP) have been investigated experimentally under the different values of oil supply flow rate, bearing load and shaft speed. The vibration characteristics of the pad fluttering are estimated by measuring the time signal of circumferential distribution of the film thickness and the cascade plot of the response of the relative displacement between the bearing and the shaft. It is shown that the vibration frequency of the pad fluttering has a sub-synchronous frequency and 31mos1 does not change by the increase of shaft speed. However the vibration amplitude is increased by the increase of shaft speed. From those experimental results, pad fluttering can be thought of as a self-excited vibration. The incipient pad fluttering velocity is increased by the increase of oil supply rate and by the decrease of bearing load. It is observed that the vibration amplitude of the pad fluttering can be decreased by the control of supply oil flow rate effectively. And also It is known that the outbreak of pad fluttering does not concern with the shaft vibration.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.325-330
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• 1999

The dynamic behavior analysis of air-lubricated tilting pad journal bearing which considers start-up, running and shutdown Process were performed. By carrying out the experiment of shaft vibration, measurement of the vibration amplitudes supported by air lubricated tilting pad bearing and analysis of the result, we found more accurate dynamic behavior of the system. There were many investigations in these bearings, but dynamic behavior of startup, shutdown and running process were lacked. By using the experimental data we found the accurate dynamic behavior of the system.

• Tribology and Lubricants
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• v.10 no.2
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• pp.30-38
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• 1994

The thermohydrodynamic(THD) performance of a large tilting pad journal bearing is investigated both theoretically and experimentally. The theory takes into account the three dimensional variation of lubricant viscosity and eddy viscosity, and the inlet pressure. Owing to the inlet pressure effect, the film pressure and load capacity are increased but the mixing temperature and bearing surface temperature are decreased. The continuous distribution of the film pressure and film thickness and the bearing surface temperature are measured along with the shaft speed and the bearing load, and they are compared with the theoretical results. The results obtained by the experiment are in good agreement with those by the theory including the inlet pressure effect. It is suggested that the three dimensional turbulent THD analysis including the inlet pressure effect is very useful to predict the performance of the large tilting pad journal bearing more accurately.

• Tribology and Lubricants
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• v.9 no.2
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• pp.29-35
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• 1993

The thermohydrodynamic(THD) performance of a large tilting pad journal bearing in laminar and turbulent flow regions is investigated experimentally. The continuous shaft surface temperature, and bearing surface temperature are measured along with the shaft speed and the bearing load for various flow rates. It is observed that the shaft surface temperature is constant in the circumferential direction and increases with the increase of shaft speed in both low and high shaft speed region, however, there exist transition region where the shaft surface temperature decreases with the increase of shaft speed. When the turbulence occurs in the lubricant film, both the inlet and maximum bearing surface temperature steeply increase and the temperature gradient in the circumferential direction decreases.

• The KSFM Journal of Fluid Machinery
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• v.2 no.2 s.3
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• pp.32-38
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• 1999

An experimental study is performed to investigate the frequency effects of the excitation force on the linear stiffness and damping coefficients of a LOP (load on pad) type five-pad tilting pad journal bearing with the diameter of 300.91 mm and the length of 149.80 mm. The main parameter of interest in the present work is excitation frequency to shake the test bearing. The excitation frequency is controlled independently, using orthogonally mounted hydraulic exciters. The relative movement between the bearing and shaft, and the acceleration of the bearing casing are measured as a function of excitation frequency using the different values of bearing load and shaft speed. Measurements show that the variation of excitation frequency has quite a little effect on both stiffness and damping coefficients. Both direct stiffness and damping coefficients in the direction of bearing load decrease by the increase of shaft speed, but increase with the bearing load.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.173-179
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• 1998

An experimental study is performed to investigate the frequency effects of the excitation force on the linear stiffness and damping coefficients of a LOP (load on pad) type five-pad tilting pad journal bearing with the diameter of 300.91 mm and the length of 149.80 mm. The main parameter of interest in the present work is excitation frequency to shake the test bearing. The excitation frequency is controlled independently, using orthogonally mounted hydraulic exciters. The relative movement between the bearing and shaft, and the acceleration of the bearing casing are measured as a function of excitation frequency using the different values of bearing load and shaft speed. Measurements show that the variation of excitation frequency has quite a little effect on both stiffness and damping coefficients. Both direct stiffness and damping coefficients in the direction of bearing load decrease by the increase of shaft speed, but increase with the bearing load.