Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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Performance Predictions of Gas Foil Journal Bearing with Shim Foils

심포일을 갖는 가스 포일 저널 베어링의 성능 예측

  • Hwang, Sung Ho (Graduate School, Dept. of Mechanics and Design, Kookmin University) ;
  • Moon, Chang Gook (Graduate School, Dept. of Mechanics and Design, Kookmin University) ;
  • Lee, Jong Sung (Global Advanced Tech center, Advanced Component Team, Hanon System) ;
  • Kim, Tae Ho (School of Mechanical Engineering, Kookmin University)
  • 황성호 (국민대학교 대학원 기계설계학과) ;
  • 문창국 (국민대학교 대학원 기계설계학과) ;
  • 이종성 (한온시스템 선행부품개발팀) ;
  • 김태호 (국민대학교 기계공학부)
  • Received : 2018.04.04
  • Accepted : 2018.05.22
  • Published : 2018.06.30
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Abstract

This paper presents a computational model of a gas foil journal bearing with shim foils between the top foil and bumps, and predicts its static and dynamic performance. The analysis takes the previously developed simple elastic foundation model for the top foil-bump structure and advances it by adding foil models for the "shim foil" and "outer top foil." The outer top foil is installed between the (inner) top foil and bumps, and the shim foil is installed between the inner top foil and outer top foil. Both the inner and outer top foils have an arc length of $360^{\circ}$, but the arc length of the shim foil is shorter, which causes a ramp near its leading edge in the bearing clearance profile. The Reynolds equation for isothermal and isoviscous ideal gas solves the hydrodynamic pressure that develops within the bearing clearance with preloads due to the ramp. The centerline pressure and film thickness predictions show that the shim foil mitigates the peak pressure occurring at the loading direction, and broadens the positive pressure as well as minimum film thickness zones except for the shortest shim foil arc length of $180^{\circ}$. In general, the shim foil decreases the journal eccentricity, and increases the power loss, direct stiffness, and damping coefficients. As the shim foil arc length increases, the journal eccentricity decreases while the attitude angle, minimum film thickness, and direct stiffness/damping coefficients in the horizontal direction increase.

Keywords

References

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