• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.315-318
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• 2007

A dynamic simulation of a turbo-shaft engine was performed for analysis of transient-state and engine-starting characteristics using the MATLAB/SIMULINKTM. The turbo-shaft engine was modelled based on thermodynamic and rotor dynamic relations. The analysis of engine starting characteristics was performed by monitoring the rate of the pressure, temperature and mechanical torque changes along the engine stations by the torque input generated from the accessary power unit and transmitted to the power turbine. The simulation of the transient-state characteristics of the engine was performed under fuel flow rate increase from the steady-state condition. For the future study, engine control unit will be added to the basic turbo-shaft engine model to enhance capability of engine performance simulation.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.3
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• pp.259-267
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• 2005

The effects of hull flexibility on shaft alignment are growing as ship sizes are increased mainly for container carrier and LNG carrier. In order to consider hull flexibility on a propulsion shafting system, standardization of ship service conditions is necessary because hull deformation is continuously variable according to ship service conditions. How to summarize ship service conditions is suggested based on practically applicable four viewpoints : hull, engine, loading and sea status. Effects of the external forces acting on a ship propulsion shafting system are generally commented. Several design criteria regulated by classification societies are pointed at issue which seems to have Insufficient technical background. A qualitative verification is carried out to point out the invalidity of the assumption of effective supporting position. In this work, an elastic nonlinear multi-supporting bearing system is introduced as a key concept of the elastic shaft alignment. Hertz contact theory is proved to be more proper one than projected area method in calculation of the nonlinear elastic stiffness of the bearing, The squeezing and oil film pressure calculations in the long journal bearing like an after stern tube bearing are recognized as a necessary process for elastic shaft alignment design.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.412-418
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• 2020

Generally, the propeller shaft that constitutes the ship shaft system has different patterns of behavior due to the ef ects of engine power, propeller load and eccentric thrust, which increases the risk of bearing failure by causing local load variations. To prevent this, different studies of the propulsion shaft system have been conducted focused the relative inclination angle and oil film retention between the shaft and the support bearing, mainly with respect to the Rules for the Classification of Steel Ships. However, in order to secure the stability of the propulsion shaft via a more detailed evaluation, it is necessary to consider dynamic conditions, including the transient state due to sudden change in the stern wakefield. In this context, a 50,000 DWT vessel was analyzed using the strain gauge method, and the effects of propeller shaft movement were analyzed on the starboard rudder turn which is a typical transient state during normal continuous rate(NCR) operation in ballast draught condition. Analysis results confirm that the changed propeller eccentric thrust acts as a force that temporarily pushes down the shaft to increase the local load of the stern tube bearing and negatively affects the stability of the shaft system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.977-980
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• 2011

In this paper, explain to development of low pressure axial compressor performance test rig in KARI. Performance test rig consist of a entrance section, rotor, stator, shaft, rig housing, bearing housing and exit section. Test rig design structural optimization to rotor dynamics analysis of the simplified rotor-shaft assembly and flow analysis of entrance/exit section.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.537-547
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• 2015

A Monte Carlo (MC) simulation was conducted to predict the reliability of a newly developed pyrotechnic pin puller. The reliability model is based on the stress-strength interference model that states that failure occurs if the stress exceeds the strength. In this study, the stress is considered to be the energy consumed by movement of a pin shaft, and the strength is considered to be the energy generated by pyrotechnic combustion for driving the pin shaft. Failure of the pin puller can thus be defined as the consumed energy being greater than the generated energy. These energies were calculated using a performance model formulated in the previous study of the present authors. The MC method was used to synthesize the probability densities of the two energies and evaluate the reliability of the pin puller. From a probabilistic perspective, the calculated reliability was compared to a deterministic safety factor. A sensitivity analysis was also conducted to determine which design parameters most affect the reliability.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.173-179
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• 2001

The torsional or axial critical vibration of the order coinciding with the number of propeller blades is simultaneously excited by the harmonic tangential or radial forces acting on the crank shaft and by the harmonic of the same order from the propeller. The exciting torque of propeller is relatively small comparing with that of crank side, but the exciting force of propeller rather larger than that of crank shaft. With this situation, the exciting force of propeller cannot neglect if the axial vibration of propulsion shafting is calculated. With the propeller in its optimal angular position, i.e. its excitation effect opposed to that of the engine, the stresses at the critical revolution will largely cancel themselves out. In this paper, a method of optimizing the angular propeller position with regard to torsional and axial vibration is studied. The optimal relative angle is determined theoretically by calculation results of coupled torsional-axial vibration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.31-31
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• 1997

우수한 비강성과 비강도를 지닌 복합재료를 이용한 자동차용 추진축(Propeller Shaft)의 사용은 자동차의 구조정량화, 소음/진동 감소, 승차감 향상 측면에서 개선된 효과를 기대할 수 있다. 본 연구에서는 탄소섬유/에폭시 필라멘트 와인딩(Filament Winding) 공빔을 적용한 복합재료 튜브와 금속재 플랜지 그리고 유니버셜 조인트로 구성된 상용 차의 추진축 개발과정 중 축의 진동특성에 대한 적합한 형상과 물성을 찾기 위해 유한요소법을 적용한 자유진동 해석과 FFT 해석장비를 이용한 진동실험 그리고 축을 운용속도까지 회전시켜 공진(Resonance) 현상 발생 유무를 소음량의 측정으로 판단하는 시험이 수행되었다. 그 결과 요구조건에 적합한 진동특성을 나타내는 추진축의 형상을 결정할 수 있었다.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.102-111
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• 2014

An analytical model was developed to understand the physics and predict the functional performance of a pin puller. The formulated model is based on one-dimensional gas dynamics for an ideal gas. Resistive forces against pin shaft movement were measured in quasi-static mechanical tests, the results of which were incorporated into the model. The expansion chamber pressure and the pin shaft displacement were measured from an actual firing test and compared to the model prediction. The gas generation rate was adjusted by a correction factor, and the heat transfer rate was obtained through parametric analysis. The validity of the model is assessed for additional firing tests with different amounts of pyrotechnic charge. This model can provide knowledge on how the pin puller functions, and on which design parameters contribute the most to the actuation of the pin puller. Using this model, we estimate the functional safety factor by comparing the energy generated by the pyrotechnic charge to the energy required to accomplish the function.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.376-381
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• 2009

The increasing needs for higher cargo capacity in the container vessels' fleet has led to ship builder's demand for higher power output rating engine to meet the propulsion requirement, thus, leading to the development of super large two stroke low speed diesel engines. This large sized bore engines with more than 12 cylinders are capable of delivering power output up to more than 100,000 bhp at maximum continuous rating. The thrust variation force due to axial vibration occurring in propulsion shafting of these ships are transmitted to ship structure via thrust bearing. This force may vibrate the super structure of ship in the fore-aft direction and the fatigue strength of crank shaft can be decreased by additional bending stress increase in crank shaft pin and journal. In this paper, the axial vibration of propulsion shafting system on the 14RT-flex96C super large diesel engine with 14 cylinders is identified by theoretical analysis and vibration measurement.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.785-794
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• 2005

Modern ship hulls of large oil carriers and container carrers have become more flexible with scantling optimization and increase in ship length. On the other hand. as the demand for power has increased with the ship size. shaft diameters have become larger and stiffer. Consequently. the alignment of the propulsion system has become more sensitive to hull girder deflections. resulting in difficulties in analyzing the alignment and conducting the alignment procedure. Accordingly. the frequency of shaft alignment related bearing damages has increased significantly in recent years. The alignment related damages are mostly attributed to inadequate analyses. changes in the design of the vessel. shipyards' practices in conducting the alignment. and a lack of well defined analytical criteria. The hull deflections should be considered at the design stage to minimize the bearing damage caused by hull deflection. Hull deflections can be estimated by analytical approach and reverse calculation using the measured data. The hull girder deflection analysis using the reverse calculation will be introduced in this paper.