• 제목/요약/키워드: Foil Journal Bearing

검색결과 72건 처리시간 0.022초

공기윤활 범프포일 저널 베어링의 내구성 특성에 관한 연구 (A Study on the Durability Characteristics of an Air-lubricated Bump Foil Journal Bearing)

  • 이용복;김태호;김창호;이남수;장건희
    • Tribology and Lubricants
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    • 제18권2호
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    • pp.153-159
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    • 2002
  • This paper describes a durability characteristics of an air-lubricated bump foil journal bearing for high speed turbomachinerys at room temperature. At first, lift-off test and load capacity test were performed to understand the general characteristics of an air-lubricated bump foil Journal bearing. A 52 N weighted bump foil bearing sleeve was lilted off from a rotating Journal at about 3,000 rpm, and produced a load capacity of 500 N at an operating speed of 15,000 rpm. The next was 500 cycles lift-off test with an air-lubricated bump foil journal bearing that had a molybdenum disulfide(MoS$_2$) solid lubricant coated top foil. Data from measuring bearing torque and temperature and the observation of rubbing surfAce were included in results. Therefore the results of this work will aid in proving durability of air-lubricated bump foil journal bearings.

공기윤활 범프포일 저널 베어링의 내구성 특성에 관한 연구 (A Study on the Durability Characteristics of an Air-lubricated Bump Foil Journal Bearing)

  • 김태호;이용복;김창호;이남수;장건희
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2001년도 제34회 추계학술대회 개최
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    • pp.212-219
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    • 2001
  • This paper describes a durability characteristics of an air-lubricated bump foil journal bearing for high speed turbomachinerys at room temperature. At first, lift-off test and load capacity test were performed to understand the general characteristics of an air-lubricated bump foil journal bearing. A 52N weighted bump foil bearing sleeve was lifted off from a rotating journal at about 3,000rpm, and produced a load capacity of 500N at an operating speed of 15,000rpm. The next was 500 cycles lift-off test with an air-lubricated bump foil journal bearing that had a molybdenum disulfide(MoS$_2$) solid lubricant coated top foil. Data from measuring bearing torque and temperature and the observation of rubbing surface were included in results. Therefore the results of this work will aid in proving durability of air-lubricated bump foil journal bearings.

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고속 터보기계용 공기 포일 저널 베어링의 신뢰성에 관한 연구 (A Study on the Reliability of an Air Foil Journal Bearing for High Speed Turbomachinery)

  • 김태호;이용복;김창호;이남수
    • 한국유체기계학회 논문집
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    • 제6권2호
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    • pp.7-14
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    • 2003
  • This paper describes reliability characteristics of an air foil journal bearing for high-speed turbomachinery at a room temperature. To verify the reliability of air foil journal bearing, lift-off characteristics, load carrying capacity, and 10,000 cycle start-stop test were performed with a motor-driven test rig. A lift-off test shows the relationship between the rotating speed of the shaft and the frictional torque with bearing surface. About a load-carrying capacity, the tested air foil journal bearing produced a load capacity of 500N at an operating speed of 15,000rpm, which is compared with results of numerical analysis and empirical coefficients. Finally, the trends in change of start torque, stop torque, and bearing temperature were shown during a 10,000-cycle start-stop test of an air foil journal bearing. We found that an air foil bearing performs well, as a supported bearing for the high-speed turbocompressor.

고속 터보기계용 공기 포일 저널 베어링의 신뢰성에 관한 연구 (A Study on the Reliability of an Air Foil Journal Bearing for High Speed Turbomachinery)

  • 이용복;김태호;김창호;이남수
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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    • pp.199-206
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    • 2002
  • This paper describes a reliability characteristics of an air foil journal bearing for high speed turbomachinery at room temperature. To verify the reliability of air foil journal bearing, lift-off characteristics, load carrying capacity, and 10,000 cycle start-stop test were performed with motor driven test rig. Lift-off test shows the relationship between the rotating speed of the shaft and the frictional torque with bearing surface. About load carrying capacity, the tested air foil journal bearing produced a load capacity of 500N at an operating speed of 15,000rpm, which is compared with results of numerical analysis and empirical coefficients. Finally, The trends in change of start torque, stop torque, and bearing temperature were shown during 10,000 cycle start-stop test of an air foil journal bearing. from the results of this work, an air foil bearing will be done well, as a supported bearing for high speed turbo-compressor.

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포일변형 영향계수를 이용한 공기포일베어링 해석 (Analysis of Air Foil Bearing using Influence Coefficients of a Bump Foil)

  • 김영철;이동현;김경웅
    • Tribology and Lubricants
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    • 제22권1호
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    • pp.40-46
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    • 2006
  • This paper presents the influence coefficient method to predict the deflection of bump foil precisely in the sub-structure of AFB(air foil bearing). Heshmat has introduced the simple compliance model to calculate the deflection of bump foil. But this approach can not consider the deflection of bump foil at the edge of AFB, so elasto-hydrodynamic model is insufficient to analyze in case that the eccentricity ratio is greater than 1. Peng has used the average pressure and film thickness, but this approach is not also a realistic model. Influence coefficients of a bump is calculated by finite element method, and introduced in bump deflection equations of the performance analysis of air foil bearing. The effects of the influence coefficient on the bearing performance is discussed in detail for appropriate foil design.

고속 회전 터보 기기용 포일 베어링의 불안정 진동 제진에 관한 연구 (A Study on the Suppression of Instability Whirl of a Foil Bearing for High-Speed Turbomachinery beyond the Bending Critical Speed)

  • 이용복;김태호;김창호;이남수;최동훈
    • 한국유체기계학회 논문집
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    • 제5권3호
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    • pp.7-14
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    • 2002
  • A new foil bearing, ViscoElastic Foil Bearing(VEFB) is suggested with the need for a high damping foil bearing. Sufficient damping capacity is a key technical hurdle to super-bending-critical operation as well as widespread use of foil bearings into turbomachinery. The super-bending-critical operation of the conventional bump foil bearing and the VEFB is examined, as well as the structural dynamic characteristics. The structural dynamic test results show that the equivalent viscous damping of the VEFB is much larger than that of the bump bearing, and that the structural dynamic stiffness of the VEFB is comparable or larger than that of the bump bearing. The results of super-bending-critical operation of the VEFB indicate that the enhanced structural damping of the viscoelastic foil dramatically reduces the vibration near the bending critical speed. With the help of increased damping resulting from the viscoelasticity, the suppression of the asynchronous orbit is possible beyond the bending critical speed.

공기포일 자기 하이브리드 베어링으로 지지되는 연성 축의 휨 모드 진동 제어 (Bending Mode Vibration Control of a Flexible Shaft Supported by a Hybrid Air-foil Magnetic Bearing)

  • 정세나;안형준;김승종;이용복
    • Tribology and Lubricants
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    • 제27권2호
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    • pp.57-64
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    • 2011
  • Hybrid air-foil magnetic bearing integrates two oil free bearing technologies synergetically to adopt the strengths of two bearings with minimizing their weaknesses. This paper presents bending mode vibration control of a flexible shaft supported by the hybrid air-foil magnetic bearing. An experiment set-up of a flexible shaft supported by the hybrid air-foil magnetic bearing is built. In order to verify the effectiveness of the hybrid bearing, unbalance responses of the flexible shaft supported by three different bearings: air-foil, magnetic and hybrid bearings are compared. Effect of load sharing between air-foil and magnetic bearings are investigated through changing the control gain and the rotor center position of magnetic bearing. The experimental results shows that the hybrid bearing can control the bending mode vibration of the flexible shaft effectively and an optimal performance can be achieved with an appropriate load sharing between the air-foil and the magnetic bearings.

심포일을 갖는 가스 포일 저널 베어링의 성능 예측 (Performance Predictions of Gas Foil Journal Bearing with Shim Foils)

  • 황성호;문창국;이종성;김태호
    • Tribology and Lubricants
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    • 제34권3호
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    • pp.107-114
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    • 2018
  • This paper presents a computational model of a gas foil journal bearing with shim foils between the top foil and bumps, and predicts its static and dynamic performance. The analysis takes the previously developed simple elastic foundation model for the top foil-bump structure and advances it by adding foil models for the "shim foil" and "outer top foil." The outer top foil is installed between the (inner) top foil and bumps, and the shim foil is installed between the inner top foil and outer top foil. Both the inner and outer top foils have an arc length of $360^{\circ}$, but the arc length of the shim foil is shorter, which causes a ramp near its leading edge in the bearing clearance profile. The Reynolds equation for isothermal and isoviscous ideal gas solves the hydrodynamic pressure that develops within the bearing clearance with preloads due to the ramp. The centerline pressure and film thickness predictions show that the shim foil mitigates the peak pressure occurring at the loading direction, and broadens the positive pressure as well as minimum film thickness zones except for the shortest shim foil arc length of $180^{\circ}$. In general, the shim foil decreases the journal eccentricity, and increases the power loss, direct stiffness, and damping coefficients. As the shim foil arc length increases, the journal eccentricity decreases while the attitude angle, minimum film thickness, and direct stiffness/damping coefficients in the horizontal direction increase.

공기윤활 다엽포일 저널 베어링의 회전축 부상 특성에 관한 연구 (A Study on the Lift-off Characteristics of an Air-lubricated Multi-leaf Foil Journal Bearing)

  • 이용복;김태호;김창호;이남수;장건희
    • Tribology and Lubricants
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    • 제17권4호
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    • pp.290-296
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    • 2001
  • Lift-off means that the rotating journal surface separates from the leaf surface in an air-lubricated multi-leaf foil journal bearing. Lift-off builds up minimum film thickness which will provide load capacity between leaves and journal. In this paper an analysis of air-lubricated multi-leaf foil journal bearing was performed with effects of multi-leaf foil deflection and compressible lubrication equation simultaneously. Minimum film thickness built up versus journal speed predicts the lift off characteristics and these results will be useful in designing and selecting the proper speed of the air-lubricated multi-leaf foil journal bearing.

에어 포일 스러스트 베어링의 탑포일 경사면 형상이 유동특성에 미치는 영향에 대한 수치해석 연구 (The Effects of Inclined Foil Shape on Flow Characteristics in Air Foil Thrust Bearing Using CFD)

  • 백건웅;주원구;문형욱;황성현;정성윤;박정구
    • Tribology and Lubricants
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    • 제37권4호
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    • pp.117-124
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    • 2021
  • In this study, we perform a 3D CFD conjugate analysis according to the shape of the foil ramp of the air foil thrust bearing, analyze the flow characteristics inside the bearing, and compare the results corresponding to the two shapes. Air has a lower viscosity than lubricating oil. Therefore, the thrust runner of the bearing must rotate at high speed to support the load. The gap between thrust runner and foil is significantly smaller than that of the oil bearing. Hence, it is crucial to analyze the complex flow characteristics inside the bearing to predict the complex flow inside the bearing and performance of the bearing. In addition, flow characteristics may appear differently depending on the ramp shape of the bearing foil, which may affect bearing performance. In this study, we numerically analyze the main flow path of air flowing into the bearing and the secondary flow path used for cooling the bearing using the commercial CFD software ANSYS CFX and compare the flow characteristics for straight and curved foil ramp shapes. Notably, there is a difference in the speed of the flowing air according to the shape of the ramp, which affects the bearing performance.