• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.116-120
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• 2003

In general, industrial rotating machinery have been designed to have critical speed that is above operating speed. But nowadays, they should be operated more than the first critical speed as usual with the trend of high speed and high performance of rotating machinery. Therefore, it is important to predict the accuracy rotordynamic characteristics of the high speed rotating system in advance. In this paper, the results of rotordynamic analysis about FWP(Feed Water Pump) drive turbine rotor are showed. Because the FWP drive turbine analyzed is high speed machinery operated more than the operation speed of conventional FWP drive turbine, Seismic response analysis as well as unbalance response analysis is done in order to improve the reliability of the new turbine rotor-bearing system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.313-318
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• 1996

In this paper, a parametric study of the unbalance response and the stability is carried out to show the influence of seal parameters on the response of rotor. The seal parameters optimized are the seal clearance and the seal length. The minimum quantity of a Q factor in the critical speed and the maximum quantity of a logarithmic decreement in the operating speed, avoiding the reign of resonance, are the objective function. This paper describes a new approach to find a seal parameter of rotor system. The optimization method is used genetic algorithms, which are search algorithms based on the mechanics of natural selection and natural genetics. The results show the capability of this method and indicate that an optimal design of seals can improve the unbalance and the stability of rotor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.925-934
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• 2005

The dynamic response due to the unbalance and crack and the quasi-static response due to gravity are analytically derived based on the complex transfer matrix. The additional slope is expressed as function of the bending moment at crack position based on the fracture mechanics concept, and inversely the bending moment is expressed as function of the additional slope at the crack position. At each angle step during the shaft revolution, the additional slope and bending moment are calculated by an iterative method. The transient behavior is considered by introducing Fourier series expansion concept for the additional slope. Simulation is carried out for a simple rotor similar to those available in the literature and comparison of the basic crack behavior is shown. Using the additional slope, the cracked rotor behavior is explained with the crack depth increased: the magnitude of the additional slope increases and the closed crack duration during a revolution decreases as the crack depth increases. The direction of unbalance is also shown as a factor to affect the crack breathing. Whirl orbits are shown near the sub-critical speed ranges of the rotor.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1137-1147
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• 2005

The dynamic response due to the unbalance and crack and the quasi-static response due to gravity are analytically derived based on the complex transfer matrix. The additional slope is expressed as function of the bending moment at crack position based on the fracture mechanics concept, and inversely the bending moment is expressed as function of the additional slope at the crack Position. At each angle step during the shaft revolution, the additional slope and bending moment are calculated by an iterativemethod. The transient behavior is considered by introducing Fourier series expansion concept for the additional slope. Simulation is carried out for a simple rotor similar to those available in the literature and comparison of the basic crack behavior is shown. Using the additional slope, the cracked rotor behavior is explained with the crack depth increased: the magnitude of the additional slope increases and the closed crack duration during a revolution decreases as the crack depth increases. The direction of unbalance is also shown as a factor to affect the crack breathing. Whirl orbits are shown near the sub-critical speed ranges of the rotor.

• Tribology and Lubricants
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• v.2 no.2
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• pp.20-26
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• 1986

The paper presents an analytical investigation of the unbalance vibrations of a pump rotor. The analysis applies to rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter rotor elements and discreate bearings, seals, and impellers. The dynamic hydraulic force of bearing, seal and impeller elements are represented by four stiffness coefficients arid four damping coefficients. Numerical results are presented for unbalance response associated with various kinds bearing, and with effects of seal and impeller forces.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.862-862
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• 2007

• The KSFM Journal of Fluid Machinery
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• v.13 no.5
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• pp.35-42
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• 2010

This paper deals with the development of analytical model of a turbocharger and its detail rotordynamic analysis. Two analytical models, which are verified by experimental modal testing, are proposed and the analytical model including rotor shaft extended to compressor and turbine wheel end side is chosen. A rotordynamic analysis includes the critical map, Campbell diagram, stability, and unbalance response, especially nonlinear transient response considering nonlinear fluid film force at bearings. Although the linearized analysis accurately predicts the critical speeds, stability limit, and stability threshold speed, the predicted vibration results are not valid for speeds above the stability threshold speed since the rotor vibrates with a subsynchronous component much larger than the one synchronous with rotor speed. Hence, for operating speed above the stability threshold, a nonlinear transient analysis considering nonlinear fluid film force must be performed in order to accurately predict vibration responses of rotor and guarantee results of analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.644-645
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.11-19
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• 1997

이 글의 내용은 다음과 같다 1.서론 2.Rotor Dynamics에서의 Quotes & Misquotes/역사 바로 세우기 3.Rotor Dynamics는 이대로 좋은가\ulcorner 3.1.Rotor Dynamics와 Balancing 3.2.Balancing은 ultra-precision process 3.3.Unbalance response의 현황과 문제점 3.4.Jeffcott Rotor[Jeffcott 1919] 3.5.National Rotor Dynamics Test Facility의 필요성 4.결론

• Journal of KSNVE
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• v.7 no.3
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• pp.467-475
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• 1997

A rotor-bearing system has been investigated, including internal damping and axial torque using finite dynamic elements. A procedure is presented for dynamic modeling of rotor-bearing system which consist of finite dynamic shaft elements, rigid disk, and bearing and seal. A finite dynamic element model including the effects of rotatory inertia, gyroscopic moments, axial force, and axial torque is developed using the frequency dependent shape function. The natural whirl speeds, stability, and unbalance response of rotor system are calculated on several cases and compared with the conventional finite elements.