• 한국정밀공학회지
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• 제29권1호
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• pp.121-125
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• 2012

This paper presents the friction and anti-wear characteristics of nano-oil with a mixture of a refrigerant oil and carbon nano-particles in the thrust slide-bearing of scroll compressors. Frictional loss in the thrust slide-bearing occupies a large part of total mechanical loss in scroll compressors. The characteristics of friction and anti-wear using nano-oil is evaluated using the thrust bearing experimental apparatus for measuring friction surface temperature and the coefficient of friction at the thrust slide-bearing as a function of normal loads up to 4,000 N and rotating speed up to 3,200 rpm. It is found that the coefficient of friction increases with decreasing rotating speed and normal force. The friction coefficient of carbon nano-oil is 0.023, while that of pure oil is 0.03 under the conditions of refrigerant gas R-22 at the pressure of 5 bars. It is believed that carbon nano-particles can be coated on the friction surfaces and the interaction of nano-particles between surfaces can be improved the lubrication in the friction surfaces. Carbon nano-oil enhances the characteristics of the anti-wear and friction at the thrust slide-bearing of scroll compressors.

• 열병합발전
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• 통권37호
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• pp.18-21
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• 2004

There are several bearing system at large steam-turbines in thermal power plant. The bearing system is one of the most important parts of rotating machinery. The steam turbine vibrations mainly depend on the bearing oil the shaft alignment condition. This paper describes on the steam turbine abnormal vibration due to the oil whip in terms of the shaft alignment in the thermal power plant.

• 대한기계학회논문집A
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• 제27권7호
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• pp.1058-1064
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• 2003

Noise estimating procedures of oil lubricated journal bearings are presented. Nonlinear analysis of rotor-bearing system including unbalance mass of the rotor is performed in order to obtain acoustical properties of the bearing. Acoustical properties of the bearing are investigated through frequency analysis of the pressure fluctuation of the fluid film calculated from the nonlinear analysis. Noise estimating procedures presented in this paper could aid in the evaluation and understanding of acoustical properties of oil lubricated journal bearings.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1015-1019
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• 2001

There are several bearing systems at the large steam-turbines in thermal power plant. The bearing system is one of the most important parts of rotating machinery. The steam turbine vibrations mainly depend on the bearing oil and the shaft alignment condition. This paper describes on the steam turbine abnormal vibration due to the oil whip in terms of the shaft alignment in the thermal power plant.

• Journal of Mechanical Science and Technology
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• 제14권7호
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• pp.737-743
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• 2000

This paper presents the effects of circumferential groove on the minimum oil film thickness in engine bearings. The fluid film pressures are calculated by using the infinitely short bearing theory for the convenience of analysis. Journal locus analysis is performed by using the mobility method. A comparison of minimum oil film thickness of grooved and ungrooved bearing is presented. It is found that circumferential $360^{\circ}$ groove only reduces the absolute magnitude of the oil film thickness, but $180^{\circ}$ half groove affects the shape of film thickness curve and position of minimum oil film thickness.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.234-238
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• 2002

Lubricating oil supply system is an essential instrument for safe turbine operation. A lubricating condition may cause the abnormal vibration of turbine. In this paper we have discussed the abnormal vibration of turbine due to lubricating oil. Dusts of the air usually attach to end of the oil deflector and contact particles of the bearing oil. Dusts which were contacted particles of the bearing oil were changed into carbon deposit because of high temperature. therefore, carbon deposits occur abnormal vibration of the turbine when they contact a rotor. So, we have solved this problems through the various maintenance.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.113-114
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• 2002

Radial, tilting 12-pad proceeding bearings are applied as the radial bearings of vertical rotors of water turbines. The mean loads are stable at the peripheral speeds of proceeding reaching 50 m/s. The operation of tilting 12-pads proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions have been obtained by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss, oil flow, maximum oil film pressure, maximum temperature have been computed for different load angle of bearing.

• 한국유체기계학회 논문집
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• 제6권1호
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• pp.51-56
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• 2003

The feasibility study on the oil-free turbocharger supported by air foil bearings is investigated. Using the perturbation method, dynamic characteristics of air foil bearings are calculated based on the static equilibrium position of a turbocharger rotor is predicted. With collaboration of calculated stiffness and damping of foil bearing, rotordynamic analysis is performed using the finite element method. The effects of bump compliance and bearing clearance on rotordynamic characteristics of the oil-free turbocharger such as the critical speeds, eccentricity ratio, vibration amplitude and stability are investigated.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.186-193
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• 2001

In the high pressure state, the leakage flow rate of hydraulics is one of serious problems and the great reason to decrease the volume efficiency. In this paper, I tried to clarify tribology characteristics for the slipper hydrostatic bearing in swash plate type axial piston pumps and motors by means of experiment . I measured the leakage flow rate between swash plate and piston shoe with change the supply pressure and oil temperature at a swash plate angle of 0。 . And I also investigated the slipper pocket pressure and calculated oil film thickness for theoretical method. So. 1 have analyzed the tribology characteristics of hydrostatic bearing for leakage flow rate and oil film thickness with oil temperature and supply pressure.

• Tribology and Lubricants
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• 제34권5호
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• pp.183-190
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• 2018

Tilting pad journal bearing is widely used for steam turbines because of its excellent dynamic stability. As the turbine capacity increases, power loss in the bearings becomes a matter of concern. Power loss in tilting pad journal bearings can be reduced by increasing the bearing clearance and reducing the pad arc length. In this study, the tilting pad journal bearing is tested by changing the seal tooth clearance to verify the static characteristics of the bearing. Bearing power loss and bearing metal temperature are evaluated to compare the bearing's performance and reliability for several test cases. The test bearing is a tilting pad journal bearing with 300.62mm inner diameter and 120.00mm active length. The bearing power loss, its metal temperature, and oil film thickness are measured and evaluated based on the rotor's rotational speed, oil flow rate, and bearing load. Test results show that a tilting pad journal bearing with large seal tooth clearance has 40% lower power loss compared with a bearing with a small seal tooth clearance. As the seal tooth clearance is increased, the power loss of the tilting pad journal bearing decreases. However, with respect to the bearing metal temperatures, a detuning point is observed that makes the minimum bearing metal temperature. Moreover, as the seal tooth clearance is increased, the oil film thickness increases due to high viscosity.