• 수산해양교육연구
• /
• 제28권3호
• /
• pp.645-652
• /
• 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.

• Journal of Advanced Marine Engineering and Technology
• /
• 제40권7호
• /
• pp.580-586
• /
• 2016

추진효율 향상을 위해 개발된 초장행정 엔진은 저속에서도 큰 출력을 낼 수 있는 장점이 있는 반면에 이전에 비해 비틀림진동의 기진력은 상당히 증가하였다. 따라서 이전에는 튜닝 휠 또는 플라이휠만으로도 제어가 가능하였던 선박들도 연료절약형 초장행정 엔진이 탑재되는 경우에는 비틀림진동 댐퍼를 적용해야만 제어가 가능하다. 본 논문에서는 비틀림진동 제어를 위해 적용된 점성-스프링 댐퍼의 동특성을 확인하고 해당 축계에 최적 동특성을 갖는 점성-스프링 댐퍼를 설계하여 비틀림진동 특성을 검토하였다. 또한, 일부 엔진증속 지연현상을 지닐 우려가 있는 선박의 경우에는 대상축계의 진동 특성을 고려하여 최적댐퍼 설계이론에 따라 선정된 파라미터를 적절히 조정함으로써 과도한 피로누적에 따른 축 절손현상을 방지할 수 있는 축계 비틀림진동 제어 방안을 제시하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권1호
• /
• pp.33-41
• /
• 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.

• Journal of Advanced Marine Engineering and Technology
• /
• 제38권6호
• /
• pp.632-638
• /
• 2014

선박용 저속 2행정 디젤엔진의 선체 탑재 후 본체 진동제어를 위한 방법 중 하나로 마찰식 톱브레이싱과 유압식 톱브레이싱의 사용이 널리 이용되고 있으며 이들의 선택은 선주에게 일임되어져 왔다. 특히, 최근에 이르러 톱브레이싱 설치목적에 반하여 선체강성의 상대적 저하는 주 공진회전수를 상용회전수내에 존재하게 만들었고 마찰식 톱브레이싱이 장착된 선박에서 이와 관련된 사고 사례가 보고되었다. 이에 따른 효율적 해결방안으로 다양한 형태의 선박에 대하여 광범위한 진동측정이 제시되었다. 본 논문에서는 이를 바탕으로 톱브레이싱 형식에 따른 엔진 본체 진동의 특성을 확인하였고 엔진 본체 진동을 제어하기 위하여 보다 효율적인 방법에 대하여 고찰하였다.