# Offset 베어링을 활용한 터보냉동기의 회전체동역학 설계

• 이창중 (LG전선(주) 공조사업부) ;
• 박용석 (인하공업전문대학 기계과) ;
• 이준근 (LG전선(주) 생산기술센터)
• Published : 2005.02.01
• 71 9

#### Abstract

A rotor dynamic analysis is implemented to confirm the vibration stability of the high speed centrifugal chiller coupled with gear system. As the rotating speed of the centrifugal chiller under investigation is increased up to 17605rpm at the pinion rotating part, the bearing instability is getting higher and, furthermore, the rotor-bearing system might experience a few critical speed which lead to system failure due to the excessive vibration. In this study, considering the loading capacity and stability conditions, offset journal bearings are adopted for the pinion rotating system and general cylindrical bearings are used for motor part. From the modal analysis, the system is found to be stable as the critical damping ratio which shows the damping characteristics of the system are positive over all operating ranges, and in addition, the synchronous rotating frequency does not come across with any whirl natural frequency. From these results the authors confirm the vibration stability of the rotor-bearing system suggested in this study.

#### Keywords

Rotor Dynamic Analysis;Offset Journal Bearing;Centrifugal Chiller;Critical Speed

#### References

1. On Development of High Efficiency Commercial Turbo Chiller($2^{nd}$ Stage), 2000, Ministry of Commerce, Industry and Energy
2. On Development of High Efficiency Commercial Turbo Chiller($3^{rd}$ Stage), 2001, Ministry of Commerce, Industry and Energy
3. Ruhl, R. and Booker, J., 1972, 'A Finite Element Model for Distributed Parameter Turborotor Systems,' Journal of Engineering/or Industry, pp. 126-132
4. Nelson, H, 1980, 'A Finite Rotating Shaft Element Using Timoshenko Beam Theory,' Journal of Mechanical Design, Vol.2,No.4,pp.793-803
5. Lee, An Sung and Jeong, Jinhee, 1999, 'Rotor Dynamic Analysis of a Turbo-Chiller with Varying Gear Loadings,' Journal of Noise and Vibration, Vol. 9, No.5, pp. 1042-1049
6. Theodossiades S. and Natsiavas S., 2001, 'On Geared Rotor Dynamic Systems with Oil Journal Bearings,' Journal of Sound & Vibration,' Vol. 243, No.4, pp. 721-745 https://doi.org/10.1006/jsvi.2000.3430
7. Rao, J. S., 1996, Rotor Dynamics 3rd Edition, New Age International Publishers, London, pp. 155-196
8. API Standard 617, 1988, Centrifugal Compressors for General Refinery Service
9. Chen, W. J., 1998, 'A Note on Computational Rotor Dynamics,' Journal of Vibration and Acoustics, Vol. 120, pp.228-233 https://doi.org/10.1115/1.2893810
10. Mohiuddin, M.A. and Khulief, Y. A., 1999, 'Coupled Bending Torsional Vibration of Rotors Using Finite Element,' Journal of Sound and Vibration, Vol. 223, No.2, pp.297-316 https://doi.org/10.1006/jsvi.1998.2095