• 한국안전학회지
• /
• 제19권1호
• /
• pp.131-136
• /
• 2004

탄성회전축을 위한 실제적이고 효과적인 댐퍼를 개발하기 위하여 4개의 새로운 스퀴즈 필름 댐퍼들이 실험적으로 연구되었다. 이들 중에서 원통형 부쉬 댐퍼가 가장 효과적인 것으로 선택되었고 볼베어링으로 지지된 실험 회전축에 적용되었다. 이러한 회전축은 위험속도를 지나서 안정된 운전이 관찰되었다.

• Tribology and Lubricants
• /
• 제36권4호
• /
• pp.215-231
• /
• 2020

The paper presents extensive survey and review of experimental and analytical researches on fluid film bearings and squeeze film dampers (SFDs) for turbomachinery available in open literature (major archival international journals) published recently (2018 and 2019 only). Over 60 published research works are reviewed based on the research topics and objectives, the types of bearings, size of bearings, and main design parameters with a brief summary of experiments and/or predictions in each work. Some important findings and general observations about the experimental and/or predictive data are also presented. There are several major trends observed throughout the survey. A large portion of the papers focuses on bearing surface textures and effect of operating and assembly conditions on static and/or dynamic forced performances, as well as bearing surface roughness and wear patterns. Researches on geometry of orifices and recesses in hydrostatic (or hybrid) bearings, as well as bearing system stability predictions using thermohydrodynamic analysis and computational fluid dynamics (CFD), are considered as significant topics. Studies on SFDs mainly focus on experimental identification of force coefficients for various SFD geometries and sealing conditions. Reliable experiments of fluid film bearings and SFDs along with the development of experimentally benchmarked predictive tools enable reinforcement of the path for reliable implementations of the bearing components into high performance rotating machinery operating at extreme and harsh conditions. The extensive list of sources of recent experiments in the available open literature is a welcome addition to the analytical community to gauge the accuracy of predictive tools.

• 한국소음진동공학회논문집
• /
• 제13권7호
• /
• pp.517-523
• /
• 2003

This paper presents response property of the squeeze mode type mount using Magneto-Rheological fluid (MR fluid) . The MR mount for the isolation of multi-directional vibrations was constructed in this study. Both the mechanism and shape of the mount are the same as squeeze film dampers for a rotor system. In the present work, the performance of the mount was experimentally Investigated according to the magnetic field strength. The experimental results present that the MR mount can effectively reduce the vibration in a wide range of frequency by controlling the applied electromagnetic filed strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents In this study.

• Tribology and Lubricants
• /
• 제5권2호
• /
• pp.101-106
• /
• 1989

Various squeeze film dampers have been theoretically and experimentally studied for flexible rotors. A cylindrical bush damper among them was selected and applied in a test rotor supported with ball bearings. A quiet running of the rotor over a critical speed was observed.

• 한국소음진동공학회논문집
• /
• 제15권3호
• /
• pp.354-363
• /
• 2005

Squeeze film dampers (SFDs) have been commonly used to effectively enhance the dynamic behavior of the rotating shaft supported by rolling element bearings. However, due to the recent trends of high operating speed, high load capacity and light weight in rotating machinery, it is becoming increasingly important to change the dynamic characteristics of rotating machines in operation so that the excessive vibrations, which may occurparticularly when passing through critical speeds or unstable regions, can be avoided. Semi-active type SFDs using magneto-rheological fluid (MR fluid), which responds to an applied magnetic field with a change in rheological behavior, are introduced in order to find its applications to rotating machinery as an effective device attenuating unbalance responses. In this paper, a semi-active SFD using MR fluid is designed, tested, and identified to investigate the capability of changing its dynamic properties such as damping and stiffness.In order to apply the MR-SFD to the vibration attenuation of a rotor, a systematic approach for determining the damper's optimal location is investigated, and also, a control algorithm that could improve the unbalance response characteristics of a flexible rotor is proposed and its control performance is validated with a numerical example.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.1005-1011
• /
• 2004

Squeeze film dampers (SFDs) have been commonly used to effectively enhance the dynamic behavior of the rotating shaft supported by rolling element bearings. However, due to the recent trends of high operating speed, high load capacity and light weight in rotating machinery, it is becoming increasingly important to change the dynamic characteristics of rotating machines in operation so that the excessive vibrations, which may occur particularly when passing through critical speeds or unstable regions, can be avoided. Semi-active type SFDs using magneto-rheological fluid (MR fluid), which responds to an applied magnetic field with a change in rheoloaical behavior, are introduced in order to find its applications to rotating machinery as an effective device attenuating unbalance responses. In this paper, a semi-active SFD using MR fluid is designed, tested and identified by means of linear analysis to investigate the capability of changing its dynamic properties such as damping and stiffness. Furthermore, the proposed device is applied to a rotor system to investigate its potential capability for vibration attenuation: an efficient method for selecting the optimal location of the proposed damper is introduced and control algorithm that could improve the unbalance response properties of a flexible rotor is also proposed.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1992년도 제15회 학술강연회초록집
• /
• pp.77-81
• /
• 1992

스퀴즈 필름 댐퍼 (Squeeze Film Damper, SFD)는 구조가 단순하면서도 감쇠성능이 우수하여 구름베어링에 지지된 고속회전체의 댐퍼로 이용되고 있으며 특히 대부분의 항공기용 터보엔진에 장착되어 고속회 전체의 댐퍼로서의 우수성을 보여주고 있다. 또한 동력기계의 단위 무게당 고출력화 경향으로 인하여 회전체의 경량화와 고속회전은 더욱 절실히 요구되고 있다. 이에따라 기계의 회전속도를 제 1차 또는 제 2차 위험속도(critical speed)이상까지 상승시켜야 하므로 SFD의 활용범위는 앞으로도 점차 증가할 것이다. 본 논문에서는 Swift-Stieber 경계조건을 적용하여, 공동현상이 발생하는 무한 폭 SFD의 유막력과 감쇠계수를 구한 후 강성 및 유연회전체의 정상상태 응답을 해석함으로써 공동현상이 회전체-SFD계의 진동에 미치는 영향을 연구하고자 한다.

• Tribology and Lubricants
• /
• 제13권1호
• /
• pp.70-75
• /
• 1997

The lubrication characteristics of high-speed ball bearings at oil-starvation have been investigated empirically using the bearings employed in small industrial gas turbine engines. For the close structural simulation, experiments carried our with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be applied to the design and the development of gas turbine engines. Testing was done by simulating the oil-starvation conditions in engines, such as stopping the oil-supply to the bearing during normal operating, starting without oil-supply at atmospheric temperature, and accelerating with oil-supply at atmospheric temperature. From this study, the relative comparison of the frictional resistance and the resistance due to the bearing cavity oil was demonstrated visually, and the resistance due to the bearing cavity oil was dominant in the resistance of bearing at high speed.

• Tribology and Lubricants
• /
• 제12권4호
• /
• pp.28-34
• /
• 1996

The lubrication characteristics of high-speed ball bearings have been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flow rates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 2969 N axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1996년도 제24회 춘계학술대회
• /
• pp.86-93
• /
• 1996

The lubrication characteristics of high-speed ball bearings has been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flowrates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 303 kgf axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.