The KSFM Journal of Fluid Machinery (한국유체기계학회 논문집)

Korean Society for Fluid machinery (한국유체기계학회)
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Subsynchronous Vibration Behavior of Turbocharger Supported by Semi Floating Ring Bearing

세미 플로팅 링 베어링으로 지지된 터보차저의 Subsynchronous 진동 특성

  • Lee, Donghyun (Department of system dynamics, Korea Institute of Machinery &Materials) ;
  • Kim, Youngcheol (Department of system dynamics, Korea Institute of Machinery &Materials) ;
  • Kim, Byungok (Department of system dynamics, Korea Institute of Machinery &Materials) ;
  • Ahn, Kookyoung (Department of environment and energy systems, Korea Institute of Machinery & Materials) ;
  • Lee, Youngduk (Department of environment and energy systems, Korea Institute of Machinery & Materials)
  • 이동현 (한국기계연구원 시스템 다이나믹스 연구실) ;
  • 김영철 (한국기계연구원 시스템 다이나믹스 연구실) ;
  • 김병옥 (한국기계연구원 시스템 다이나믹스 연구실) ;
  • 안국영 (한국기계연구원 환경기계 시스템 연구실) ;
  • 이영덕 (한국기계연구원 환경기계 시스템 연구실)
  • Received : 2016.07.25
  • Accepted : 2016.11.01
  • Published : 2017.02.01
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Abstract

The small turbocharger for the automotive application is designed to operate up to 200,000 rpm to increase system efficiency. Because of high rotation speed of turbocharger, floating ring bearing are widely adopted due to its low friction loss and high rotordynamic stability. This paper presents a linear and nonlinear analysis model for a turbocharger rotor supported by a semi-floating ring bearing. The rotordynamic model for the turbocharger rotor was constructed based on the finite element method and fluid film forces were calculated based on the infinitely short bearing assumption. In linear analysis, we considered fluid film force as stiffness and damping element and in nonlinear analysis, the fluid film force was calculated by solving the time dependent Reynolds equation. We verified the developed theoretical model by comparing to modal test results of test rotors. The analysis results show that there are two unstable modes, which are conical and cylindrical modes. These unstable modes appear as sub-synchronous vibrations in nonlinear analysis. In nonlinear analysis, frequency jump phenomenon demonstrated when vibration mode is changed from conical mode to cylindrical one. This jump phenomenon was also demonstrated in the test. However, the natural frequency measured in the test differs from those obtained using nonlinear analysis.

Keywords

References

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