• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.260-265
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• 1997

Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric rotation parts and gas forces induced by the difference in pressure between compression and suction gases6 Rotor-journal bearing system is nonlinear since the stiffness and damping coefficients of the lubricating oil film are not constant in the bearings. In this paper, the program for predicting the behaviors of rotor-journal bearing system of rotary compressor is developed. Finite element modeling is used to analyze the flexible rotor. The numerical results are compared with experimental results. The location of balancer weight are suggested for reducing rotor whiring displacement.

• 대한조선학회논문집
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• 제42권3호
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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.

• 한국소음진동공학회논문집
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• 제23권6호
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• pp.520-526
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• 2013

This article presents the reduction of vibration generated by an automobile fuel pump. In order to analyze the vibration of the fuel pump, a simplified dynamic model is established, which is composed of a rigid rotor and a equivalent springs. The equivalent stiffnesses of the upper and lower assemblies are evaluated by the comparison of modal testing results and the finite element analysis. The stiffness for the oil film of the journal bearing is extracted by using Reynold's equation. In addition, the time responses for the vibration of the fuel pump are computed by using a commercial multi-body dynamics software, RecurDyn. Based on these results, some design suggestions are proposed to reduce the vibration of an automobile fuel pump.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.138-143
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• 2005

Recently, it is much more required to approach the accurate shaft alignment analysis according to the tendency of active showing in large container vessel and that of the heavy weight of propeller in connection with it. Shaft alignment calculation lies upon how the pressure apply on bearings properly in operation of main engine and how the stress of shaft puts within that of limit of bearing material and how the movement of shaft is prospected owing to propeller forces and moments. Therefore, we have conducted the shaft alignment calculation of very large container vessel considering the deformation of hull structure and the propeller forces and moments and the static and dynamic condition of shaft. The calculation results show the pressure distribution of aft bush and the movement of shaft in bearing. The shaft alignment calculation helps the stable application of shaft alignment, which was proved in sea trial.

• Tribology and Lubricants
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• 제28권6호
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• pp.265-271
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• 2012

In the preceding Part I study, for improving the unbalance response vibration of a large PRT motor-generator rotor fundamentally by design, a series of design analyses were carried out for bearing improvement by retrofitting from original plain partial journal bearings, applied for operation at a rated speed of 1,800 rpm, to final tilting pad journal bearings. To satisfy evenly key basic lubrication performances such as the minimum lift-off speed and maximum oil-film temperature, a design solution of 5-pad tilting pad journal bearings and maximizing the direct stiffness by about two times has been achieved. In this Part II study, a detailed rotordynamic analysis of the large PRT motor-generator rotor-bearing system will be performed, applying both the original plain partial journal bearings and the retrofitted tilting pad journal bearings, to confirm the effect of rotordynamic vibration improvement after retrofitting. The results show that the rotor unbalance response vibrations with the tilting pad journal bearings are greatly reduced by as much as about one ninth of those with the plain partial journal bearings. In addition, for the tilting pad journal bearings there exist no critical speed up to the rated speed and just one instance of a concerned critical speed around the rated speed, whereas for the plain partial journal bearings there exist one instance of a critical speed up to the rated speed and two instances of concerned critical speeds around the rated speed.