• Title/Summary/Keyword: Unbalance Response Analysis

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Rotordynamics of a Centrifuge Rotor-Bearing System for 100,000 rpm Operation (100,000 rpm 운전용 원심분리기 로터-베어링 시스템의 회전체동역학 해석)

  • 이안성;김영철;박종권
    • Journal of KSNVE
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    • v.8 no.3
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    • pp.450-456
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    • 1998
  • A rotordynamic analysis is performed with a centrifuge rotor-bearing system for the raing speed of 100,000 rpm. The system is composed of a centrifuge rotor(or simply the rotor), flexible shaft, motor rotor and shaft, and two support rolling element bearings of the motor shaft. Design goals are to achieve wide separation margins of critical speeds and favorable unbalance responses of the rotor at the associated critical speeds. The latter requirements are especially important as the system crosses multiple numbers of critical speeds and as the system may not have enough separaton margins around the rating speed. As the system adopts an extra-flexible shaft, it is shown that the rotor has satisfactory small unbalance responses over higher criticals while having an unsatisfactory large one at the first critical. To supress this a bumper ring or guide bearing needs to be installed at a suitable location of the flexible shaft. It is also shown that even with the flexible shaft the dynamics of the motor must be incoporated into the full system model to accurately identify the fourth critical speed, which is close to the rating speed, and higher ones. The analysis is based on the finite element method.

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Finite Element Model Updating and Vibration Analysis of PMDC Motor Rotor System (영구자석형 직류전동기 축계의 유한요소모델 개선과 진동해석)

  • Kim, Y.H.;Ha, J.Y.;Lee, J.G.;Kim, S.H.;Yang, B.S.
    • Journal of Power System Engineering
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    • v.11 no.1
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    • pp.20-27
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    • 2007
  • In this paper, finite element modeling was performed for vibration analysis of a rotor system installed in sunroof motor, and analysis process was developed for natural frequency and unbalance response analysis. At the same time, to reduce analysis modeling error caused by the difference between analysis and measured values, finite element model updating was conducted using an optimization algorithm, i.e. hybrid genetic algorithm and simulated annealing (HGASA) method. For this end experimental modal test was carried out and by using the measured frequency response function (FRF), model updating was performed considering both cases where core coil was removed and included. And acceptable result was obtained. Also, dynamic property coefficient of bush bearing which influences vibration response of the rotor system was estimated.

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Critical Speed Analysis of the Liquid Rocket Turbopump (액체로켓 터보펌프의 임계 속도 해석)

  • Jeon, Seong-Min;Kwak, Hyun-Duck;Yoon, Suk-Hwan;Kim, Jin-Han
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.6
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    • pp.92-99
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    • 2005
  • Numerical analyses of critical speed and mass unbalance response are performed for a 30 ton thrust turbopump. The stiffness and damping of ball bearings and non-contact seals are quantified under aerodynamic and hydrodynamic loads induced by a fuel pump and turbine. Critical speed margin and tip displacements of the rotating parts are evaluated using a three-dimensional finite element method. The results are used to ensure the soundness of the rotordynamic design using an one-dimensional transfer matrix method. A further study shows that sufficient resonance margin may be assured via controlling the stiffness of the rotor support by employing an additional elastic ring to the bearing support.

Analytical evaluation of water injection pump dynamic characteristic (물 분사 펌프 동특성의 해석적 평가)

  • Lee, JongMyeong;Lee, JeongHoon;Ha, JeongMin;Ahn, ByungHyun;Gu, DongSik;Choi, ByeongKeun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.60-64
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    • 2013
  • Water injection pump produced the 1st oil well through the high pressure after the Deep water oil well drilling. After finish the work it is hard to produce only using itself pressure due to low pressure. Therefore it can be increased recovery factor through the injection seawater of high pressure. Is the key equipment used in the marine plant and it is developing at many industries. In this paper, Analyze changes in the natural frequency due to the stiffness of the bearing. Analyze the critical speed of the natural frequency due to the change of operation speed. And evaluate the Stability. And then analyze the displacement and clearance through the unbalance response this way has contributed to the reliability of the developing product. Through a mathematical analysis.

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Design and Operation Characteristics of a Two-Stage Compressor (이단 압축기의 동력학적 설계 및 운전 특성에 관한 연구)

  • Lee, Yong-Bok;Kim, Tae-Ho;Kim, Chang-Ho;Lee, Nam-Soo;Choi, Dong-Hoon
    • The KSFM Journal of Fluid Machinery
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    • v.5 no.1 s.14
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    • pp.55-61
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    • 2002
  • The feasibility of an oil-free, motor-driven, two-stage centrifugal compressor supported by air bump bearings is investigated. This centrifugal compressor is driven by a 75 kW motor at an operating speed of 39,000 RPM, and a pressure ratio of the compressor is set up to 4. The analysis is performed by using bearing equilibrium position, heaving stillness, Campbell diagram, unbalance response, and stability. It is demonstrated in this paper that air bump bearings can be adopted well to an oil-free, motor-driven, centrifugal compressor. Specially, Cu-coated bump bearings have enough damping force to reduce a synchronous unbalance for rigid modes of the two-stage compressor. Futhermore, this concept may be applied to the flexible rotor system such as high speed turbomachinery with a super critical speed.

Forced Vibration Analysis of the Hard Disk Drive Spindle Systems (하드디스크 드라이브 회전축계의 강제진동해석)

  • Lim, Seung-Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1601-1608
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    • 2000
  • This paper is concerned with the forced flexural vibration analysis of hard disk drive (HDD) spindle systems with multiple thin disks, supported by two ball bearings based on the finite element model. This is the extension of the previous work which analytically modeled every system component taking into account its structural flexibility and also the centrifugal stiffening effect especially for the disks. Among the end results, the forced time response is expectedly useful for the vibration control of the spindle itself or the position servo control of the magnetic head. On the other hand, the steady state responses such as the frequency response function and the unbalance response are useful for system identification. Futhermore, through a coordinate transformation the equations of motion is also derived with respect to the inertial frame for convenient analyses of certain classes.

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Rotordynamic Analysis of a Turbo-Chiller with Varying Gear Loadings Part I ; A Driving Motor-Bull Gear Rotor-Bearing System (터보 냉동기의 변동 기어하중을 고려한 로터다이나믹 해석 Part I : 구동 모터-불기어 로터-베어링 시스템)

  • 이안성;정진희
    • Journal of KSNVE
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    • v.9 no.3
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    • pp.593-599
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    • 1999
  • A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

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The Improvements of Vehicle Vibration Characteristics Using Modal Contribution (모우드 기여도 분석을 이용한 차량의 진동특성 개선)

  • 안지훈;지상현;고병식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.51-56
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    • 1998
  • This paper presents modal contribution method to reduce vehicle vibration. Normal mode analysis is performed to obtain modal vector matrix. The proposed method uses this modal vector matrix to evaluate forced response of an active mode to the applied engine forces and the rotating force due to wheel unbalance mass. Comparing the responses, of the specific active mode with one another, it can be easily done to determine most contributed mode in the interesting frequency band. Then we can find dominant bushes by the strain energy distribution of the mode. Vibration response is decrease with modification of those bushes.

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Analysis on the Dynamic Response of Vertical Pumps Subjected to Arbitrary Foundation Excitation (임의 기초여진에 의한 입형 펌프의 동적 응답해석)

  • 여운동
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.1
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    • pp.57-64
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    • 1990
  • It is important in design of vertical pumps to consider arbitrary foundation excitation in addition to rotor vibration due to unbalance. In this study, a model of a vertical pump was developed for the analysis of its dynamic response. The vertical pump was modeled with lumped masses and springs which represent mult-cylinderical and rotor structure. A dynamic simulation program was developed and numerical calculation on the above mentioned problems were carried out.

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