• Journal of Advanced Marine Engineering and Technology
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• 제40권9호
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• pp.743-748
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• 2016

선박의 주기관으로 통상 사용되는 디젤기관은 터빈기관과 같은 회전기관과 달리 왕복동기관이기 때문에 실린더의 폭발력과 피스톤의 왕복관성력에 의한 불평형 관성력 및 관성모멘트, 실린더내의 주기적인 변동가스압력 등으로 인하여 본질적인 진동문제를 안고 있다. 이것은 엔진의 진동은 소음의 원인이 되고, 선체구조나 인접구조물에 전달되어 2차진동이 발생시키는 경우가 많다. 본 연구는 선박의 엔진과 축계의 자유진동해석과 엔진 폭발에 의한 강제진동해석을 하고, 나아가서 플라이휠에 부진동 장치인 동흡진기를 설치하여 진동을 줄이는 방법을 제안하고자 한다.

• 한국소음진동공학회논문집
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• 제17권7호
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• pp.572-578
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• 2007

Two stroke low speed diesel engines are widely used for marine propulsion or as power plant prime mover. These engines have many merits which includes higher thermal efficiency, mobility and durability. Yet various annoying vibrations occur sometimes in ships or at the plant itself. Of these vibrations, torsional vibration is very important and dictates a careful investigation during the engme's initial design stage for safe operation. With the rule and limit on torsional vibration in place, shaft strength fatigue due to torsional vibration however demands further analysis which possibly can be incorporated in the classification societies' rule and limit. In addition, the shaft's torsional vibration stresses can be calculated equivalently from accumulated fatigue cycles number due to transient torsional vibration in time domain. In this paper, authors suggest a new estimation method combined with Palmgren-Miner equation. A 6S70MC-C ($25,320ps{\times}91rpm$) engine for ship propulsion was selected as a case study. Angular velocity was measured, instead of shaft's strain, for simplified measurement and it was converted to torsional vibration stress for accumulated fatigue cycle numbers in shafting life time. Likewise, the accumulated fatigue calculation was compared with shaft fatigue strength limit. This new method can be further realized and confirmed in ship with two stroke low speed diesel engine.

• 대한조선학회논문집
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• 제43권4호
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• pp.512-520
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• 2006

The effects of flexibilities of supporting structures on shaft alignment are growing as ship sizes are Increasing mainly for container carrier and LNG carrier. But, most of classification societies not only do not suggest any quantitative guidelines about the flexibilities but also do not have shaft alignment design program considering the flexibility of supporting structures. A newly developed program, which is based on innovative shaft alignment technologies including nonlinear elastic multi-support bearing concept and hull deflection database approach, has S basic modules : 1)fully automated finite element generation module, 2) hull deflection database and it's mapping module on bearings, 3) squeezing and oil film pressure calculation module, 4) optimization module and 5) gap & sag calculation module. First module can generate finite element model including shafts, bearings, bearing seats, hull and engine housing without any misalignment of nodes. Hull deflection database module has built-in absolute deflection data for various ship types, sizes and loading conditions and imposes the transformed relative deflection data on shafting system. The squeezing of lining material and oil film pressures, which are relatively solved by Hertz contact theory and built-in hydrodynamic engine, can be calculated and visualized by pressure calculation module. One of the most representative capabilities is an optimization module based on both DOE and Hooke-Jeeves algorithm.

• 수산해양기술연구
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• 제43권3호
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• pp.222-231
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• 2007

This paper represents a basic statistical examination on the navigability of ocean-going ship from the point of estimating the time lasting period when propeller racing occurred by using the basic probability theory and the statistics. The propeller racing is one of the most important seakeeping qualities in relation to the safety of the main engine and shafting system. The trend of the racing has been mainly investigated in order to estimate allowable maximum propeller diameter, operation of ocean-going ships, etc.. In those studies, the propeller racing generally and mainly means the situation (propeller exposed) in which the relative motion amplitude between ship hull and wave surface would exceed a depth of point in rotary disk propeller. Therefore, it seems that the magnitude of the amplitude and its exceeding frequency of propeller racing have been examined as a principal subject of study as usual. However, the time during which the amplitude exceeds the depth of point, that is, the propeller exposes in the air, must be also one of most important factor affecting the trend of propeller racing. Then, this paper proposes a new practical method for estimating the time lasting of exposed propeller related to propeller racing in rough-confused seas on the basis of the linear strip theory and the statistics. And, numerical examples of estimating the propeller racing probability are given for four wide ship forms. Finally the usefulness of the proposed method for predicting propeller racing based on the time lasting period is discussed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2013년도 추계학술대회
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• pp.163-164
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• 2013

양방향차도선(CAR-FERRY)은 육지와 도서, 도서와 도서 간을 연결하는 교통수단 기능과 지속적인 해양관광객의 수요증가에 따른 해양관광 연계 연안여객 운송수단 역할을 하고 있다. 이에 따른 양방향 차도선은 이용의 편리성이 증대 되고 접안으로 인한 해양 사고를 줄일 수 있다. 양방향차도선은 등흘수(even) 상태로 프로펠러가 양쪽에 있기 때문에 프로펠러가 소직경 저회전으로 인하여 전진 운항 시에 반력에 의한 축계 및 프로펠러 파손 등이 발생할 수 있다. 이에 따른 엔진 출력, 선형, 비틀림 진동 등에 따른 감속기, 탄성커플링 선정, 횡진동 및 축계정렬(Shaft alignment)을 고려한 축계설계(베어링 수량, 폭, 간격)를 하여 선체의 추진축 1차 지지부의 구조에 대한 건전성을 평가하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제40권4호
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• pp.288-294
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• 2016

선박이 고출력화, 대형화 됨에 따라 추진축의 강성은 증가한 반면에 선체는 고장력 후판을 사용하므로 이전의 선체보다 훨씬 더 쉽게 변형되는 실정이다. 이는 기존의 선박보다 더욱 정교한 축계정렬이 요구됨을 의미한다. 본 연구에서는 최근 친환경 고효율 선박으로 등장한 5만DWT급 석유화학제품운반선을 대상으로 스트레인게이지법을 이용한 계측을 실시하고 축계 베어링 반력 및 선체 변형량 분석을 수행하였다. 계측은 선박의 통상 흘수 변화를 고려한 5개 조건에서 수행하여 추진축계가 선체 변형의 영향 하에서도 허용치를 만족하는지 여부를 확인하였다. 또한 이론적 계산방법, 잭업법 및 스트레인게이지법의 결과를 상호 비교하여 해석의 신뢰성을 교차검증하였다.