• Tribology and Lubricants
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• 제7권1호
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• pp.28-34
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• 1991

The performance of the counterrotating floating ring journal bearing is analysed with isothermal finite bearing theory. The effect of counterrotating speed of the sleeve on the performance of the bearing is investigated. It is shown that counterrotating floating ring journal bearings properly designed can have considerable load capacity at the same counterrotating speed, while conventional circular journal bearing with one fluid film cannot. Investigating the relationship between the frictional torques on the ring due to the inner and outer films and the rotational speed of the ring, the stability of the equilibrium state is identified and the operating characteristics of the counterrotating floating ring journal bearing according to the method of acceleration or deceleration of the rotational speeds of the journal and sleeve are clarified. It is theoretically confirmed that floating ring journal bearings can be used in counterrotating journal-bearing system and become good substitutes for rolling bearings in counterrotating systems.

• International Journal of Fluid Machinery and Systems
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• 제8권1호
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• pp.46-54
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• 2015

Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions from thrust bearing and operation conditions of hydro-generator units. Because the oil circulatory and cooling system with thrust-ring-pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump. On another hand, the head and flow rate are varying with the operation conditions of hydro-generator units and the oil circulatory and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulatory and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization is purposed in this paper. Firstly, the head and flow rate at different conditions are decided by 1D flow numerical simulation of the oil circulatory and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and flow rate from the simulation. Thirdly, the flow passage geometry matching optimization between thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulatory and cooling system are collaborative hydrodynamic optimized with predicted head-flow rate curve and the efficiency-flow rate curve of thrust-ring-pump. The presented methodology has been adopted by DFEM in design process of thrust-ring-pump and it shown can effectively improve the performance of whole system.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제1권)
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• pp.23-29
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• 2006

선박의 충돌회피 방법을 제시하는 관점에 있어, 두 선박의 조우각도에 따른 속력이 충분히 고려되어야 할 것이다. 하지만 선박의 충돌회피를 위해 새롭게 연구된 근접상황 선박충돌회피지원 모델의 Safe-Guard Ring 설정은 본선과 상대선박의 속력비가 약 1.7 이하로 제한되어 있으므로 제한된 범위 이외의 경우에서 충돌 위험이 존재 할 수 있다. 따라서 본 연구에서는 두 선박이 조우하는 각도 및 속력을 고려한 Safe-Guard Ring 설정을 연구함으로써 안전한 충돌회피 조종을 위한 선박충돌회피모델을 제시하고자 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.735-743
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• 2001

This study was performed to evaluate the dynamic behavior of turbo pump unit. The acceptable separate margin of 1st critical speed was obtained by the use of elastic-ring inserted ball bearing, while the poor separate margin of 1$\^$st/ critical speed was appeared in the case without the elastic-ring. In addition, the results show that the stiffness and damping of plain seals gain more separate margin of 2nd critical speed. However the wear or the failure of seals could reduce the 2$\^$nd/ critical speeds near the operating speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1150-1153
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• 2006

Many commercial high speed and lightly loaded rotating machineries incorporate floating ring bearings (FRBs) owing to their low cost and reduced power losses. Many researchers have developed various analytical models to predict the performance and the stability of those rotor-bearing systems with FRBs. However, most of the models failed to predict stability of the rotor-bearing systems with FRBs. FRBs comprise two fluid films in series and the ratio of floating ring speed to journal speed reflects the equilibrium state of the two fluid films. Therefore the speed ratio is one of the main concerns in the analysis of FRBs. This paper provides the experimental results of the speed ratio which enables one to verify of the analysis model for FRBs.

• 한국생산제조학회지
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• 제19권5호
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• pp.609-615
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• 2010

Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.

• 한국항해항만학회지
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• 제30권10호
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• pp.779-785
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• 2006

선박의 충돌회피 방법을 제시하는 관점에 있어, 두 선박의 조우각도에 따라 속력이 충분히 고려되어야 할 것이다. 하지만 선박의 충돌회피를 위해 새롭게 연구된 근접상황 선박충돌회피지원 모델의 안전경계영역(Safe-Guard Ring) 설정은 본선과 상대선박의 속력비가 약 1.7이하로 제한되어 있으므로 제한된 범위 이외의 경우에서 충돌 위험이 존재 할 수 있다. 따라서 본 연구에서는 두 선박이 조우하는 각도 및 속력을 고려한 안전경계영역 설정을 연구함으로써 안전한 충돌회피 조종을 위한 선박충돌회피모델을 제시하고자 한다.

• Tribology and Lubricants
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• 제17권2호
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• pp.130-137
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• 2001

In this paper, the thermal effects on the performance of floating ring journal bearing are investigated theoretically. The numerical analyses include pressure drop at inner film due to a centrifugal force, fluid momentum effects of supply oil into inner film and thermal effects in lubricating films. All performance data are presented as the rotating speed of journal from 10,000 rpm to 70,000 rpm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.46-48
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• 1999

This paper treated the design and characteristics of high speed motor/generator with ring wound stator for the flywheel energy storage system. The most important advantages of the ring-wound motor is the slotless stator, i.e. no cogging torque, no space harmonic of air-gap flux density, etc. Because of these advantages, ring wound type motor is suitable to operate at the high speed.

• KSTLE International Journal
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• 제2권2호
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• pp.127-132
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• 2001

The steady state performance of the counterrotating floating ring journal bearings is analyzed with isothermal finite bearing theory. The effect of counterrotating speed of the sleeve on the performance of the bearing is investigated. It is shown that counterrotating floating ring journal bearings can have considerable load capacity at the same counterrotating speeds, while conventional circular journal bearings with one fluid film cannot. Investigating the relationship between the frictional torques exerted on the ring due to the inner and outer films and the rotational speed of the ring, the stability of the equilibrium state is identified and the operating characteristics of the counterrotating floating ring journal bearing according to the method of acceleration or deceleration of the rotational speeds of the journal and sleeve are clarified. It is theoretically confirmed that floating ring journal bearings can be used in counterrotating journal-bearing system and become good substitutes for rolling bearings in counterrotating systems.