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Keywords: rotors
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Journal Articles
Article Type: Research Papers
J. Tribol. October 2011, 133(4): 041702.
Published Online: October 14, 2011
.... The bearings are modeled as micro-channels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2011, 133(2): 021703.
Published Online: March 22, 2011
... still remain unsolved or poorly understood, and one of them is thermal management. This paper presents transient three-dimensional thermohydrodynamic (3D THD) model of radial foil bearings to predict transient thermal behavior of the bearing-rotor system. The transient model involves transient energy...
Journal Articles
Article Type: Research Papers
J. Tribol. January 2011, 133(1): 011702.
Published Online: December 3, 2010
... vibration. Numerical results show that the reduced damping coefficients and the threshold speed can be effectively enhanced by giving suitable pad pivot stiffness and damping simultaneously, and this analytical method can be applied to analyze dynamical behavior of the tilting-pad journal bearing rotor...
Journal Articles
Article Type: Research Papers
J. Tribol. July 2010, 132(3): 032201.
Published Online: June 15, 2010
...Adolfo Delgado; Luis San Andrés Squeeze film dampers (SFDs) aid to reduce excessive vibration levels due to rotor imbalance and to raise stability thresholds in rotor-bearing systems. SFDs commonly include end seals to increase their damping capability with a lesser lubricant flow. Seals also aid...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2010, 132(2): 021704.
Published Online: April 14, 2010
...Donghyun Lee; Daejong Kim A new thermohydrodynamic analysis model for bump air foil bearings with a detailed thermal model of bump foil structures and rotor is presented. In the developed model, temperatures of lubricating air film, top foil, bump foils, bearing sleeve, and rotor are calculated...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2010, 132(2): 021702.
Published Online: March 25, 2010
... framework and linear elasticity. The oil film pressure and flow are considered to follow the modified Reynolds equation, which includes the contribution from controllable radial oil injection. The Reynolds equation is solved using a two-dimensional finite element mesh. The rotor is considered to be rigid...
Journal Articles
Article Type: Research Papers
J. Tribol. January 2010, 132(1): 011701.
Published Online: November 11, 2009
...Tae Ho Kim; Luis San Andrés An engineered thermal management is fundamental to the application of gas foil bearings (GFBs) as turboshaft supports in rotorcraft propulsion systems. The paper presents a model for the thermal energy transport in a rotor-GFB system operating at high temperature...
Journal Articles
Article Type: Research Papers
J. Tribol. October 2009, 131(4): 041705.
Published Online: September 23, 2009
... rarefactions with the Poiseuille and Couette flow rate correctors. The gas film in the rotor-bearing system is modeled as stiffness and damping elements with coefficients dependent on the exciting frequency. The dynamic coefficients are then obtained by solving the linearized MMGL equations. The equations...
Journal Articles
Article Type: Research Papers
J. Tribol. October 2009, 131(4): 041001.
Published Online: September 22, 2009
...Aaron Rimpel; Daejong Kim Hydrodynamic flexure pivot tilting pad gas bearings (FPTPGBs) can enable successful operation of oil-free microturbomachinery and FPTPGBs with radially compliant pads permit rotor centrifugal and/or thermal growth to exceed original bearing clearances and achieve higher...
Journal Articles
Article Type: Research Papers
J. Tribol. July 2009, 131(3): 032001.
Published Online: May 27, 2009
... barriers to achieving stable high-speed operation with micro-gas-bearings are governed by (1) stringent fabrication tolerance requirements and manufacturing repeatability, (2) structural integrity of the silicon rotors, (3) rotordynamic coupling effects due to leakage flows, (4) bearing losses and power...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2009, 131(2): 021101.
Published Online: March 3, 2009
... such as high rotor-bearing stability and less severe thermal issues (due to multipad configurations) than foil gas bearings. However, extension of the application of the tilting pad gas bearings to flexible rotors and harsh environments with external vibrations/impacts poses significant design challenges...
Journal Articles
Article Type: Research Papers
J. Tribol. January 2009, 131(1): 011703.
Published Online: December 2, 2008
... dynamic analysis on the rotor and the pads. Furthermore, the equivalent dynamic coefficients of a full tilting-pad gas bearing also can be obtained by solving the dynamic forces of the bearing. The effects of the perturbation frequency on the dynamic coefficients are presented in this paper...
Journal Articles
Article Type: Research Papers
J. Tribol. October 2008, 130(4): 041102.
Published Online: August 1, 2008
...A. Bouzidane; M. Thomas; A. A. Lakis This research project aims to study the nonlinear dynamic behavior of a rigid rotor supported by hydrostatic squeeze film dampers (HSFDs). The investigated HSFD consists of four hydrostatic bearing flat pads fed by capillary restrictors. A nonlinear hydrostatic...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2008, 130(2): 021103.
Published Online: April 25, 2008
...G. Belforte; F. Colombo; T. Raparelli; V. Viktorov A test bench for rotors supported by air bearings floating on O-rings is designed in order to study the whirl phenomenon and characterize the stability threshold with damping elements mounted on bearings. The work includes a description of the test...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2008, 130(2): 021102.
Published Online: April 22, 2008
..., power, or a control system failure. In the drop-down, when the rotor drops from the magnetic field on the retainer bearings, the design of the retainer bearings has a significant influence on the dynamic behavior of the rotor. In this study, the dynamics of an active magnetic bearing supported rotor...
Journal Articles
Article Type: Research Papers
J. Tribol. April 2008, 130(2): 021101.
Published Online: March 3, 2008
...M. Saint Raymond; M. E. F. Kasarda; P. E. Allaire Rotors supported by active magnetic bearings (AMBs) can spin at high surface speeds with relatively low power losses. This makes them particularly attractive for use in flywheels for energy storage in applications such as electric vehicles...
Journal Articles
Article Type: Technical Papers
J. Tribol. October 2007, 129(4): 818–828.
Published Online: March 15, 2007
... with stress free inner boundary conditions. The thermoelastic solution is then demonstrated for a transient temperature distribution induced by inner boundary frictional heating due to rotor contact, which is derived from a dynamic Hertzian pressure distribution. The application is to a relatively short...
Journal Articles
Article Type: Technical Papers
J. Tribol. July 2007, 129(3): 628–639.
Published Online: March 2, 2007
... and measured structural loss factor indicate that the damping of underlying structure can suppress the maximum peak at the critical speed very effectively but not the onset of hydrodynamic rotor-bearing instability. However, the damping plays an important role in suppressing the subsynchronous vibrations under...
Journal Articles
Article Type: Technical Papers
J. Tribol. April 2007, 129(2): 375–383.
Published Online: January 9, 2007
... for axial, cylindrical, and conical modes. The stability thresholds with respect to each mode are graphed as functions of the bearing number. For axial and cylindrical modes, the threshold parameter is the rotor mass. For the conical mode, the threshold parameter is an equivalent mass that is dependent...
Journal Articles
Article Type: Technical Papers
J. Tribol. April 2007, 129(2): 348–353.
Published Online: December 5, 2006
... as well as the pad degrees of freedom are determined. Based on these dynamic coefficients, the perturbation equations including self-excited motion of the rotor and rotational motion of the pads are derived. The complex eigenvalues of the equations are computed and the pad critical mass identified...