• Title, Summary, Keyword: stern tube

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A Feasibility Study on the Application of Stern Tube Unit for the Twin Skeg LNG Carrier (쌍축 LNG 운반선에 대한 선미관 유닛 적용 가능성 연구)

  • Shin, Sang-Hoon;Sung, Young-Jae;Park, Jeong-Yong;Han, Bum-Woo
    • Journal of the Society of Naval Architects of Korea
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    • v.53 no.4
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    • pp.282-289
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    • 2016
  • Traditional construction method of the stern tube is difficult to control the process and needs excessive working hours. Recently in order to resolve these issues, stern tube unit has been installed for some commercial vessels. The stern tube unit is a monolithic structure of bush and related components. The purpose of this study is to carry out a feasibility study for application of the stern tube unit for a 174K twin skeg LNG carrier. In this study, a 19,000 TEU container carrier installing the stern tube unit has been selected to compare with the deformations of stern for a 174K twin skeg LNG carrier.

A Study on Optimum Shaft Alignment Analysis for VLCC (VLCC의 최적 축계정렬해석 연구)

  • Kim Hyu Chang;Kim Jun Gi
    • Special Issue of the Society of Naval Architects of Korea
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    • pp.134-137
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    • 2005
  • Recently, in VLCC, shafting system is stiffer due to large engine power whereas hull structure is more flexible due to scantling optimization, which can be suffered from alignment damage by incompatibility between shafting and hull, In this study, shafting system without stern tube forward bush was adapted for less sensitive system against external factors. Also, shaft alignment analysis was considered with hull deflection at various ship loading conditions and stern tube after bush of long journal bearing was evaluated by static squeezing pressure and dynamic oil film pressure with sloping control. Whirling vibration was also reviewed to avoid resonance with propeller blade order. So, reliable shafting design for VLCC could be achieved through optimized alignment analysis for the system without stern tube forward bush.

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A Study on the Measurement and Analysis of Bearing Reaction Forces of Marine Propulsion Shafting System using Strain-Gauge (스트레인 게이지를 이용한 선박용 추진 축계의 베어링 반력 측정에 관한 연구)

  • Kim, Chul-Woo;Lee, Yong-Jin;Cho, Kwon-Hae;Kim, Ue-Kan
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.1
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    • pp.33-41
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    • 2008
  • Bearing damages by shaft misalignment have frequently been happened in marine ships. Specially. after stern tube bearing damage and failure for large crude oil carriers have been reported several times. However. the bearing reaction of the after stern tube bearing cannot be measured by jack-up test due to the hull structure condition. Therefore, when the jack-up test is used for the bearing reaction measurements, the bearing reaction for the after stern tube bearing obtained from the theoretical calculation method have to be used. In this paper, the shaft alignment on the large oil crude carrier is theoretically calculated and the differences between the calculated and actual installed bearing reaction values are compared. The bearing reactions for forward stern tube bearing and intermediate bearing are calculated by the simple formula using the strain gauge bending moments obtained from the measurements. Their reliability is confirmed by comparing the bearing reactions from jack-up test and the bearing reaction for after stern tube bearing is calculated by the same test. Also, the bearing reactions on the after stern tube bearing, forward stern tube bearing and intermediate shaft bearing under all operating conditions are calculated by using the bending moments obtained from the measurements and it is confirmed that the differences of the bearing reaction for all operating conditions are caused from hull deflection. The results of this study should prove useful for the future projects of the alignment calculation including the hull deflection effectiveness.

A Case Study on the Lateral Vibration of Shafting System in context of forward stern tube bearing for Medium Size Container Ship (중형 컨테이너 운반선 축계장치의 선미관 선수베어링 설치 유무에 따른 횡진동 사례 연구)

  • LEE, Jae-Ung
    • Journal of Fisheries and Marine Sciences Education
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    • v.28 no.3
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    • pp.645-652
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    • 2016
  • At the initial stage of propulsion shaft design, in line with shaft alignment, an intensified consideration of lateral vibration is needed to verify its operational safety. Recently the alignment problem affecting the lateral vibration has been becoming issues. However, the theoretical method of forced lateral vibration analysis is not cleary established so far and it is about to simply limited among the classification societies and international standards to avoid the blade natural frequency resonance cpm outside of ${\pm}20%$ of engine rpm at MCR. On the other hand, longer center distance between each support bearing shows an affirmative result normally in shaft alignment analysis whereas the blade order resonance speed may cause lowering near the limitation in the aspect of lateral vibration. Therefore, it is required careful attention to engineers as described above. As a method to solve the problem, it is mainly considered that remove forward stern tube bearing. In this paper, based on a medium size container ship case, theoretical study was carried out in the context of the forward stern tube bearing. The various effects and functions of forward stern tube bearing are reviewed and evaluated. Then an guidance note to lead the conclusion is proposed.

A Study on the Analysis of Oil Film in Stern Tube Bearing for Propulsion Shaft of the Ship (선박 추진축계 선미관 베어링 유막 해석에 관한 연구)

  • Song, Seung-Yong;Shuripa, Vitaly;Kim, Ki-In;Cha, Ji-Hyup;Jeon, Hyo-Jung;Kim, Jeong-Ryul
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.3-4
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    • 2005
  • With an increase in the size and power rate of ship, the stern tube bearing has become subject to severer operation conditions. Particularly it is expected to be exposed to extremely so severe lubrication conditions during low rotational operation that there is strong demand for clarifying the oil film characteristics of the stern tube bearing at the design stage with accuracy. So in this study, we conducted an analysis of the stern tube bearing characteristics taking arbitrary three-dimensional deflection of the shaft into consideration.

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Reaction force of ship stern bearing in hull large deformation based on stochastic theory

  • Zhang, Sheng-dong;Long, Zhi-lin;Yang, Xiu-ying
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.12 no.1
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    • pp.723-732
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    • 2020
  • A theoretical calculation model for ship stern bearings with large hull deformation is established and validated theoretically and experimentally. A hull simulation model is established to calculate hull deformations corresponding to the reaction force of stern bearings under multi-factor and multi-operating conditions. The results show that in the condition of wave load, hull deformation shows randomness; the aft stern tube bearing load obeys the Gaussian distribution and its value increases significantly compared with the load under static, and the probability of aft stern tube bearing load greater than 1 is 65.7%. The influence laws and levels between hull deformation and bearing reaction force are revealed, and suggestions for ship stern bearing specifications are proffered accordingly.

A Study on the Forced Fitting Method of Stern Tube Bearing for Propulsion Shafting in Ships (선박 추진축계 선미관 베어링의 강제 압입 피팅 방식에 관한 연구)

  • Cho, Kwon-Hae;Lee, Jae-Hyun;Kim, Yang-Gon
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.5
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    • pp.653-660
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    • 2010
  • The stern tube bearing is installed to the stern tube and stern boss casting by using the method of the force pressured fitting. The adequate value of the interference between the stern tube bearing and casting should be considered owing to the slip. In this study, to review and compare the fitting force and the contact pressure, the theory of thick walled cylinder is considered to clarify the formula which received from the maker. Also the fitting force and contact pressure are calculated by using the standard value of interference, Young's modulus, Poisson's ratio and friction coefficient.

The Effect of Additives on the Mechanical Properties of Rigid Polyurethane (경질 폴리 우레탄의 기계적물성에 미치는 첨가제의 영향)

  • Na, Seok-En;Choi, Hwan-Oh;Lee, Jeon-Kyu;Kim, Si-Young;Ju, Chang-Sik
    • Korean Chemical Engineering Research
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    • v.50 no.5
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    • pp.783-788
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    • 2012
  • Stern tube bearing is a shaft device playing important roles to reduce the friction of axial rotation and to support the weight of shaft. However, because there is no domestic producer of stern tube bering, imported stern tube bearings have many practical problems including prices, delivery and after services. This is why stern tube bearing should be localization. For the purpose of development of polyurethane resin for stern tube bearings, the effect of additives on the hardness, tensile strength and elongation of the polyurethane resin were systematically investigated. For the preliminary researches, depending on the type of curing agent, MOCA type and non-MOCA type polyurethanes were synthesized. Preliminary researches concluded that MOCA type polyurethane resin has more excellent mechanical properties than non-MPCA type for stern tube bearings that Tensile strength and Hardness of non-MOCA type investigated 23 D, 4.3 Mpa. Therefore, MOCA type polyurethane was adapted as base resin of this research. Silica, calcium carbonate and graphite were selected as additives for the enhancement of mechanical properties of polyurethane resin. Effect of the type and the dosage of these additives on the hardness, tensile strength, elongation of the polyurethane resin were experimentally examined. However, addition of calcium carbonate and graphite showed only minor effect on the hardness of the resin. Polyurethane resin with silica showed relatively excellent hardness, tensile strength and improved elongation.

A Study on the Development of Ship's Stern Tube Sealing System(II) -Based on Face Seals- (선미관 밀봉장치의 개발에 관한 연구 (II) -풰이스 시일을 중심으로-)

  • 김영식;전효중;왕지석;김의간
    • Journal of Advanced Marine Engineering and Technology
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    • v.15 no.5
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    • pp.47-54
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    • 1991
  • The lip seals widely used nowadays in stern tube sealing system of ships have radial sealing contact with shafts or liners, on the other hand the face seals of stern tube sealing system have axial sealing contact with seat. Because of axial sealing contact, the face seals have a large number of merits such as durability of life, simplicity of structure, easy fitting and replacement, etc. In this paper, for the purpose of development of face seals, the fundamental properties of axial sealing contact were analyzed and a trial face seal was designed and manufactured using N.B.R. rubber and Thordon which is widely used for bearing materials. The seal proper of trial face seal was made from N.B.R. rubber and the face insert was made from Thordon, thermosetting resins which are three dimensional, cross linked condensation polylmers. The performance test of trial face seal was carried out on the test bench which was specially designed and manufactured. The results were satisfactory enough to be used in practical stern tube sealing system.

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The Effect of Transient Eccentric Propeller Forces on Shaft Behavior Measured Using the Strain Gauge Method During Starboard Turning of a 4,700 DWT Ship (스트레인 게이지법을 이용한 4,700 DWT 선박의 우현 전타시 프로펠러 편심추력이 축 거동에 미치는 영향 연구)

  • Lee, Jae-ung;Kim, Hong-Ryeol;Rim, Geung-Su
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.4
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    • pp.482-488
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    • 2018
  • Generally, after stern tube bearing shows a significant increase in local load due to propeller load, which increases the potential adverse effects of bearing failure. To prevent this, research on regarding shaft alignment has been carried out with a focus on reducing the relative slope between the shaft and support bearing(s) under quasi-static conditions. However, for a more detailed evaluation of a shafting system, it is necessary to consider dynamic conditions. In this context, the results revealed that eccentric propeller force under transient conditions such as a rapid rudder turn at NCR, lead to fluid-induced instability and imbalanced vibration in the stern tube. In addition, compared with NCR condition, it has been confirmed that eccentric propeller forces given a rapid rudder starboard turn can lift a shaft from the stern tube bearing in the stern tube, contributes to load relief for the stern tube bearing.