• Title/Summary/Keyword: X-Mode Vibration

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A Study on Main Engine X-mode Vibration Phenomenon due to 2nd Node Torsional Vibration of the Marine Propulsion System (선박 추진축계의 2절 비틀림진동에 기인한 주기관 X-모드 진동 현상의 연구)

  • Lee, Donchool;Kim, Junseong;Kim, Jinhee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.9
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    • pp.806-813
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    • 2013
  • For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to 2nd node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the 2nd node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-flex82T 8 cylinder engine and 11S90ME-C 11 cylinder engine for a container ship was used as research model.

An Experimental Study of T-mode Vibration on the Diesel Power Plant (디젤 발전소의 T-mode 진동에 관한 실험적 고찰)

  • Lee, D.C.;Nam, T.K.;Bae, Y.C.;Kim, Y.H.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.411-416
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    • 2005
  • Nowadays, diesel power plant using low speed two stroke diesel engine is widely used in islands and restricted areas. Considerations were given to its benefit of high thermal efficiency, reliability and durability compared to the other prime movers. However, various types of engine vibration affect neighboring buildings to their structural vibration. For this, diesel power plant are held liable for the troubles caused by these vibration. These are mainly due to the X- and H-type engine vibrations which we excited by the X- and H- guide force moment. Authors have identified a structural vibration of new pattern called ‘T-mode vibration’ due to the torsional vibration of shafting system. In this paper, T-mode vibration is analyzed through an experimental method based on the global vibration measurement.

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Main Engine Upper Structural Vibration Phenomenon due to 2nd Node Torsional Vibration and Countermeasures on the Marine Propulsion System (선박 추진축계의 2절 비틀림 진동에 기인한 주 기관 상부 구조 진동현상과 방진 대책)

  • Lee, Donchool;Kim, Junseong;Kim, Jinhee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.549-554
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    • 2013
  • For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to $2^{nd}$ node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the $2^{nd}$ node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-82RT-flex 8 cylinder engine and 11S90S-ME 11 cylinder engine for a container ship was used as research model.

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Vibration Control on the Diesel Power Plant by the Phase Adjustment of Paralled Engines' X-Mode Vibration; (병렬 엔진의 X형 진동 위상 조정에 의한 디젤 발전 플랜트 진동 제어)

  • 이돈출;김의간;전효중
    • Journal of KSNVE
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    • v.6 no.6
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    • pp.701-708
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    • 1996
  • Diesel power plants are frequently used as a power supplier on the island and the isolated places where electric power is required. The heat efficiency of the low speed 2 stroke diesel engines is higher than those of 4 stroke diesel engines or other heat engines and further its mobility and durability is also better than other engines. They can be also easily repaired and maintained. With these advantages, demand for the use of the low speed 2 stroke diesel engine as a power source is increasing. However, there are some disadvantages with these diesel engines such as the bigger vibrating excitation forces generated by higher combustion pressure in cylinder and by the inertia force of the reciprocating parts. Further, engine vibrations are transfered into their adjacent buildings and manufacturing factories and eventually produces local vibrations. In order to reduce X-mode vibration of engine body, several methods have been introduced in the recent researches. In this paper, accordingly, a new vibrationcontrol method applying a synchrophaser and a top bracing between two diesel engines is adopted in order to reduce these structural vibrations of diesel power plant. It was experimentally verified that the structural vibrations were greatly reduced by the phase adjustment for the 6th order X-mode vibration with the synchrophaser and the top bracing.

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Investigation on Forced Vibration Behavior of Composite Main Wing Structure of A Small Scale WIG Craft Excited by Engine and Propeller (엔진 및 프로펠러에 의해 가진되는 소형 위그선 복합재 주날개의 진동 거동 해석)

  • Kong, Chang-Duck;Yoon, Jae-Huy;Park, Hyun-Bum
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.11
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    • pp.1028-1035
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    • 2007
  • this study, forced vibration analysis was performed on the composite main wing structure of a small scale WIG craft which is equipped two-stroke pusher type reciprocating engine. The structural vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the H-mode(horizontal mode), the V-mode(vertical mode) and the X-mode(twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the L-mode(longitudinal mode) with the oscillating propeller thrust which occurs.

Investigation on Forced Vibration Behavior of Composite Main Wing Structure Excited by Engine and Propeller (엔진 및 프로펠러 가진에 의한 위그선 복합재 날개 진동 해석)

  • Kong, Chang-Duk;Yoon, Jae-Huy;Park, Hyun-Bum
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.04a
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    • pp.217-221
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    • 2007
  • In this study, forced vibrations analysis was performed for main wing of small scale WIG vehicle which is equipped two-stroke pusher type propeller engine, in terms of structural. for the frequency response analysis, excitations were assumed by H-mode(Horizontal mode), X-mode(Twisted mode) which is main vibration mode of engine, and for the transient response analysis, excitations were assumed by L-mode(Longitudinal mode) with propeller thrust which is occurred when it revolution.

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Vibration Control on the Diesel Power Plant by the Phase Adjustment of Parallel Engines' X-mode Vibration (병렬 엔진의 X형 진동 위상조정에 의한 디젤 발전플랜트 진동제어)

  • 이돈출;이병운;김용근;전효중
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.04a
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    • pp.221-226
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    • 1996
  • Structural vibrations of adjacent buildings, manufacturing factories and engines on the stationary diesel power plant were increased by the variation of phase angle between two engines sometimes. In this paper, top bracings and synchrophaser have been introduced in order to reduce these vibrations. As a result, all of structural vibrations were greatly improved by the phase adjustment of 6th order X-mode vibration with these.

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Study on Forced Vibration Behavior of WIG Vehicle Main Wing Structure Excited by Propulsion System (프로펠러 엔진에 의해 가진되는 소형 위그선 주날개의 진동 거동 해석에 관한 연구)

  • Kong, Chang-Duk;Yoon, Jae-Huy;Park, Hyun-Bum
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.7-12
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    • 2007
  • Previously study on structural design of the main wing of the twenty-seat class WIG (Wing in Ground Effect) craft. In the final design, three spars construction was selected for safety in the critical flight load, and the Carbon-Epoxy material was selected for lightness and structural stability. In this study, the forced vibration analysis was performed on the composite main wing structure of the twenty-seat class WIG craft with two-stroke pusher type reciprocating engine. The vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the Y-mode (lateral mode), the Z-mode (vertical mode) and the $M_{xyz}$-mode (twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the X-mode (longitudinal mode) with the oscillating propeller thrust which occurs in operation.

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Vibration Control of Engine Body for Two Stroke Low Speed Diesel Engine using Dynamic Vibration Absorber (동흡진기에 의한 저속 2행정 디젤엔진의 본체진동 제어)

  • 이돈출;유정대;김정렬
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.6
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    • pp.631-637
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    • 2002
  • Two stroke low speed diesel engines are used as a power supplier not only for marine vessel but also diesel power plant with a benefit of its higher mobility and durability than the other thermal engines. However, there are some disadvantages such as the bigger vibrating excitation forces generated by high combustion pressure in cylinders which various kinds of vibrations are caused. In this paper, it is theoretically studied to control engine body vibration using dynamic vibration absorber. As an actual case, dynamic absorbers are designed for controlling X-mode vibration of 9K80MC-S engine on the diesel power plant and its performance is identified by the vibration test both in shop and site

Temperature stability for length extensional vibration of $Pb(Zr_{0.56}Ti_{0.44}O_{3}+x[wt%]Cr_{2}O_{3})$ceramics ($Pb(Zr_{0.56}Ti_{0.44}O_{3}+x[wt%]Cr_{2}O_{3})$세라믹스의 길이진동에 대한 온도안정성)

  • 현덕수;한성훈;이개명
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.881-884
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    • 2000
  • Recently mobile communication fields need piezoelectric ceramic resonators and filters as possible as small. The length-extensional vibration mode of a rectangular piezoelectric cesamic plate has the advantage of the small size, but the mode has not been studied sufficiently because it was not used extensively until now. In this paper, PZT + x[wt%l $Cr_20_3$ ceramics with rhombohedra1 phase were fabricated. And temperature stability for the mode of the ceramic specimen was investigated. Contrary to our expectations, addition of the stabilizer, $Cr_20_3$ did not promote the temperature stability for the mode in the PZT ceramic specimen with rhombohedra1 phase.

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