• Title/Summary/Keyword: Rotor Vibration

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Diagnosis of Excessive Vibration Signals of Two-Pole Generator Rotors in Balancing

  • Park, Jong-Po
    • Journal of Mechanical Science and Technology
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    • v.14 no.6
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    • pp.590-596
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    • 2000
  • Cause of excessive vibration with twice the rotational speed of a two-pole generator rotor for the fossil power plants was investigated. The two-pole generator rotor, treated as a typically asymmetric rotor in vibration analysis, produces asynchronous vibration with twice the rotational speed, sub-harmonic critical speeds, and potentially unstable operating zones due to its own inertia and/or stiffness asymmetry. This paper introduces a practical balancing procedure, and presents the results of the investigation on sources of the excessive vibration based on the experimental vibration data of the asymmetric two-pole rotor in balancing.

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Analysis of Outer Rotor Type BLDC motor vibration characteristics according to slot combination (Outer Rotor Type BLDC 모터의 슬롯 수에 따른 진동 특성 분석)

  • Bang, Ki-Chang;Kim, Kwang-Seok;Kwon, Joong-Hak;Ree, Yeong-Uk;Hwang, Sang-Moon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.196-201
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    • 2008
  • This paper is about electromagnetic vibration source in outer rotor type of BLDC motors. Experiments are carried out with three pole-slot combinations which are 6 slots, 12 slots, and 24 slots with 4 poles rotor. According to results, vibration sources separate into electromagnetic and mechanical factors. Using the finite element method (FEM), It is analyed that vibration characteristics of electromagnetic source in each type. This paper shows electromagnetic sensitivity to vibration, and introduces necessary point in lower vibration motors. Also rotor balance is important to prevent uneven distribution of magnetic flux between rotor and stator.

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Design of Cutter Profile and the Characteristics of Vibration for Symmetric Screw Rotor (대칭형스크류로터의 커터설계와 진동특성에 관한 연구)

  • 최상훈
    • Journal of KSNVE
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    • v.5 no.2
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    • pp.257-264
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    • 1995
  • We designed the cutter profile for symmetric screw rotor and did vibration experiment of screw rotor manufactured by the designed cutter profile. The results of this study are summarized as follows. (1) We designed the cutter profile of screw rotor (4-6)(5-6) by using numerical analysis program. (2) The maximum amplitude and variation of amplitude of 5-6 profile rotor are about 30 - 36.7% and 10 - 25% smaller than those of 4-6 profile rotor, respectively. (3) As the angular velocity of rotor changes from 100 to 300 rpm, the vibration of X, Y axis in driving shaft of 5-6 profile rotor is about 10 - 20% smaller than that of 4-6 profile rotor.

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Investigation on Excessive Vibration Signals of Two-Pole Generator Rotors in Balancing (발전기 양극 회전자 밸런싱에서의 이상 진동신호 분석)

  • 박종포;최성필;주영호
    • Journal of KSNVE
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    • v.9 no.4
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    • pp.835-840
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    • 1999
  • Cause of excessive vibration signals with twice the rotational speed of a 2-pole generator rotor in balancing for fossil power plants was investigated. The 2-pole generator rotor is treated as a typically asymmetric rotor in vibration analysis, and produces asynchronous vibration with twice the rotational speed for its own inertia and stiffness asymmetry. This paper introduces practical balancing procedure and experimental vibration data of the asymmetric 2-pole rotor in balancing, and presents the results of investigation into sources of the excessive vibration signals.

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Prediction of 2X Vibration of a Generator Rotor with Asymmetric Shaft Stiffness (비대칭 축 강성을 가지는 발전기 회전자의 2X 진동 예측)

  • Park, C.H.;Kim, Y.C.;Cho, K.G.;Yang, B.S.
    • Journal of Power System Engineering
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    • v.11 no.1
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    • pp.16-19
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    • 2007
  • The large generator rotor used in fossil power plant has the possibility of high 2X vibration due to asymmetric shaft stiffness. The generator rotor is machined into pole faces to reduce stiffness difference and then is tested through 2X vibration measurement when the balancing works are performed in the balancing shop. However, there are many cases of large difference values between 2X vibration in the balancing shop and 2X vibration in site. This paper presents a new method to estimate 2X vibration in site with more accuracy and applied for the retrofit of a fossil 400 MW class deteriorated generator. It shows that the new generator rotor is manufactured with a good 2X vibration characteristics and is operated in a low 2X vibration level although the generator rotor has high 2X vibration in the balancing shop.

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A Study on the Vibration Characteristics of Critical Speed for Rotor Shaft (회전샤프트의 위험속도에 관한 진동특성 연구)

  • Son, Choong-Yul;Lee, Kang-Su;Ryu, Young-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.9
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    • pp.961-971
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    • 2008
  • In the design of a rotor shaft, care should be taken to minimize vibration by taking into account the sources of vibration. In addition, the intensity critical speed, stability, and other related aspects of the system must be considered. especially when it is operated at a critical speed, it is important to address issues related to vibration, as an increase in the whirling response of the rotor shaft can cause damage to the shaft, destruction of the rotor parts, and detrimental abrasions on the bearings. In this thesis, the vibration characteristics of a rotor shaft are investigated through the use of the finite element method. Variations of the diameters and lengths were used to determine the effect of a rotor shaft using Beam No.188(3D linear strain beam) in ANSYS version 11.0 as a universal interpretation program for finite elements. Special care was taken to prevent excessive vibration, which can result from resonance at the initial stage, in the formulation of a dynamic design for a rotor shaft through calculations while changing the diameters and the lengths of the shaft. Moreover, the dynamic characteristics of the critical speed, total mass, D/L(diameter to length) ratio, and natural frequency were verified. Furthermore, the rotor shaft applied by bearing element was calculated and compared by using Combi No. 214(2-D spring-damper bearing).

A Study of High-speed Vacuum Balancing for 38M6 Recycle Compressor (38M6 리사이클 Compressor의 고속진동 밸런싱 사례연구)

  • 이동환;김병옥;이안성
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.657-662
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    • 2004
  • This paper presented is a case study of a real compressor rotor of a refinery plant for high speed balancing of flexible rotor. The rotor was tested in the expert high-speed balancing facility established by KIMM at early 2004. The capability of the facility can reach 40000rpm in rotation speed and 8 ton in rotor weight for high-speed balancing. The facility performs multi-plane at-speed balancing using influence coefficient from the vibration data measured at two pedestals. The test rotor had exceeded permissible criteria of vibration at initial run. But by processing a low-speed balancing at 1000 rpm and six trial run trying to calculate influence coefficient of rotor to the range of operating speed, the final result of high-speed balancing revealed a remarkable reduce of vibration at pedestal of the rotor.

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Analysis of Harmonic Vibration of Cracked Rotor (균열회전체의 고조파진동 해석)

  • Jun, Oh-Sung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.1
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    • pp.35-46
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    • 2008
  • Harmonic vibration characteristics for the general rotor model having a breathing crack are analyzed. Analyses are performed at the half critical speed ranges. The vibration characteristics are explained by using the additional slope and bending moment at the crack position and the influence coefficient showing the structural dynamic characteristics of the rotor. With the low crack depth the magnitude of the additional slope is kept constant even at the speed range at which the orbit magnitude is very sensitive to the rotational speed change. At this speed range the vibration is affected by the influence coefficient only. As the dynamic bending moment exceeds the static bending moment with the increase of crack depth. the additional slope affects the vibration amplitude of cracked rotor and the crack propagation rate increases.

Rotor Dynamics의 현황과 문제점

  • 김폴영일
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.10a
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    • pp.11-19
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    • 1997
  • 이 글의 내용은 다음과 같다 1.서론 2.Rotor Dynamics에서의 Quotes & Misquotes/역사 바로 세우기 3.Rotor Dynamics는 이대로 좋은가\ulcorner 3.1.Rotor Dynamics와 Balancing 3.2.Balancing은 ultra-precision process 3.3.Unbalance response의 현황과 문제점 3.4.Jeffcott Rotor[Jeffcott 1919] 3.5.National Rotor Dynamics Test Facility의 필요성 4.결론

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Noise and Vibration Characteristics of Externally Pressurized Air proceeding Bearings with a Circular Slot Restrictor (원형 슬롯 레스트릭터를 갖는 외부 가압 공기 저널 베어링의 소음 및 진동 특성)

  • Park, Jung-Koo;Rho, Byoung-Hoo;Kim, Kyung-Woong
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1277-1282
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    • 2003
  • The purpose of the present paper is to investigate the noise and vibration characteristics of externally pressurized air proceeding bearings with a circular slot restrictor. To do this, the nonlinear transient analysis including rotor imbalance was performed for a rotor-bearing system. The effects of radial clearance and the width of the bearing and mass eccentricity of the rotor on the noise and vibration characteristics of the bearing are also examined. The results show that the noise and vibration of the rotor-bearing system first increase up to critical speed of the system, and then decrease up to instability threshold speed of the system as the rotational speed of the rotor increases, and the noise of the bearing is markedly influenced by the mass eccentricity of the rotor and the radial clearance and the width of the bearing.

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