• Title/Summary/Keyword: 회전체역학

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Vibration Reduction or the Gear Box of an NC Machine (자동선반 기어박스의 진동방지)

  • 최헌호
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.6
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    • pp.119-125
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    • 1999
  • This article proposes the analytical and experimental approaches for the reduction of vibration generated in the gear box of an NC machine. The lateral critical speed of main spindle and torsional natural frequencies were analyzed and the impact testing of gear box was performed. These results were compared with the forced operating speeds, The vibration was much diminished by redesign of gear module and reinforcement of box structure.

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Dynamic Analysis of a Rotor System Having Thin-walled Cylinder Combined with Its Shaft (회전축에 Thin-walled Cylinder가 결합된 회전체 시스템의 동적 해석)

  • Choi, Young-Hyu;Park, Seon-Kyun;Hoong, Dae-Sun;Chung, Won-Jee
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.631-636
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    • 2000
  • In this paper a transfer method model was introduced in order to analyze critical speeds and vibration modes of a flexible rotor system, whose rotor shaft is cupped into and fitted with a thin-walled cylinder at its end. The computed analysis results were compared with those of the experimental modal test. Both results show good agreement each other. Furthermore the free-run(or run-down) test result for the real rotor system also shows that the proposed transfer matrix method modelling can be successfully applicable to analyzing accurate critical speeds(or natural frequencies) of the rotor system.

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Validation of Flexible Rotor Model for a Large Capacity Flywheel Energy Storage System (유한요소법을 이용한 대용량 플라이휠 에너지 저장 장치의 연성 회전체 모델의 검증)

  • Yoo, Seong-Yeol;Park, Cheol-Hoon;Choi, Sang-Kyu;Lee, Jeong-Pil;Noh, Myoung-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.12
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    • pp.1096-1101
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    • 2008
  • When we design a controller for the active magnetic bearings that support a large rotor, it is important to have an accurate model of the rotor. For the case of the flywheel that is used to store energy, an accurate rotor model is especially important because the dynamics change with respect to the running speed due to gyroscopic effects. In this paper, we present a procedure of obtaining an accurate rotor model of a large flywheel energy storage system using finite-element method. The model can predict the first and the second bending mode which match well with the experimental results obtained from a prototype flywheel energy storage system.

Experiment Onmodal Balancing of a Flexible Rotor Supported on Fluid Film Bearings (유막 베어링에 지지된 탄성회전체의 모드 밸런싱 실험)

  • 정시영;이동환;김영철;제양규
    • Journal of KSNVE
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    • v.5 no.2
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    • pp.235-246
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    • 1995
  • Experiment on the modal balancing of a flexible rotor supported on two kinds of fluid film bearings is performed to verify the modal balancing theory. The fluid film bearings are a tilting pad bearing and a two axial grooved journal bearing. One is inherently stable, but the other is not. The experimental result shows that the modal balancing method is effective for balancing of a high speed flexible rotor system. Besides, the critical speeds and mode shapes measured experimentally are in good coincidence with the results of rotordynamic analysis. Oil whip, which is the instability phenomenon due to fluid film force, is also observed during the experiment.

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Rotordynamic Analysis and Experiment of Superconducting Magnetic Bearings-Flywheel System (초전도 자기베어링-플리이휠 시스템의 회전체 해서 및 실험)

  • Kim, Jong-Soo;Lee, Soo-Hun
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.9
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    • pp.104-109
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    • 1999
  • The flywheel energy storage system using superconducting magnetic bearings is a device to store electrical energy as rotatioal kinetic energy by motor and to convert it to electrical energy by generator when it is necessary. The rotordynamic analysis should be performed with an adequate analytical model and equations of motion to identify the stable driving condition and the dynamic behavior. The critical speed and the unbalance response of superconducting magnetic bearings-flywheel system are studied in this paper. The analytical results show that the system has one forward whirling mode and two backward whirling models below 500rpm. The maximum displacement 0.75mm is detected at the first forward mode (385rpm)through unbalance response analysis. The analytical results are compared with the experimental result by the spin-down test. The experimental result shows that the maximum displacement is 0.7mm at 370rpm.

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Critical Speed Analysis of a 75 Ton Class Liquid Rocket Engine Turbopump due to Load Characteristics (75톤급 액체로켓엔진 터보펌프의 하중 특성에 따른 임계속도 해석)

  • Jeon, Seong-Min;Kwak, Hyun-D.;Hong, Soon-Sam;Kim, Jin-Han
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.22-29
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    • 2011
  • Critical speed of high thrust liquid rocket engine turbopump is obtained through a rotordynamic analysis and a unloaded turbopump test is peformed for validation of the numerical model. The first critical speed predicted by the numerical analysis is correlated well with the test result for the bearing unloaded rotor condition only considering mass unbalance load. Using the previous rotordynamic model, critical speed variation is estimated as a function of varied bearing stiffness due to pump and turbine radial loads with relative angle difference. From the numerical analysis, it is found that the relative angle difference of pump and turbine radial loads greatly affects the critical speed. However, additional axial load reduces the effect derived from the relative angle difference of radial loads.

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Critical Speed Analysis of a 75 Ton Class Liquid Rocket Engine Turbopump due to Load Characteristics (75톤급 액체로켓엔진 터보펌프의 하중 특성에 따른 임계속도 해석)

  • Jeon, Seong-Min;Kwak, Hyun-D.;Hong, Soon-Sam;Kim, Jin-Han
    • Journal of the Korean Society of Propulsion Engineers
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    • v.16 no.4
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    • pp.42-49
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    • 2012
  • Critical speed of high thrust liquid rocket engine turbopump is obtained through a rotordynamic analysis and a unloaded turbopump test is peformed for validation of the numerical model. The first critical speed predicted by the numerical analysis is correlated well with the test result for the bearing unloaded rotor condition only considering mass unbalance load. Using the previous rotordynamic model, critical speed variation is estimated as a function of varied bearing stiffness due to pump and turbine radial loads with relative angle difference. From the numerical analysis, it is found that the relative angle difference of pump and turbine radial loads greatly affects the critical speed. However, additional axial load reduces the effect derived from the relative angle difference of radial loads.