A Steady-State Model of a Floating Ring Bearing, Including Thermal Effects

Clarke, Desmond M.; Fall, C. J.; Hayden, G. N.; Wilkinson, T. S.

doi:10.1115/1.2920852

Cited by 28 publications

(19 citation statements)

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“…For laminar flows, ReðC=RÞ 4 1, Colburn's analogy renders the convection coefficients H ¼ 3Pr 1=3 ðk=CÞ (see references [23,12] and [24] for details).…”

Section: Discussionmentioning

confidence: 99%

Thermal effects on the performance of floating ring bearings for turbochargers

Andrés

Kerth

2004

Proceedings of the Institution of Mechanical Engineers, Part J:

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Physical models and fast computational programs aim to improve the design and performance of turbocharger (TC) rotordynamics. Most commercial automotive TCs incorporate floating ring bearings (FRBs) owing to their low cost and reduced power losses. However, persistent subsynchronous motions afflict this type of rotor/bearing system, albeit reaching limit cycles that enable their continuous operation. FRBs comprise two fluid films in series and are prone to show one or two subsynchronous instabilities over extended speed ranges of operation. A flow model for prediction of FRB forced response is detailed here. The model incorporates a lumped-parameter thermal energy balance for estimation of the lubricant viscosity and thermal growth of the rotor, bearing and floating ring. The FRB model, fully integrated into a non-linear rotordynamics computational program, predicts the floating ring speed, journal and ring eccentricities, power loss and the rotordynamic force coefficients of the inner and outer films as a function of the load applied at a given rotor speed. Knowledge of the actual load conditions, static and dynamic, and the changes in operating clearance and effective lubricant viscosity are most important for accurate estimation of a TC dynamic forced response. Predictions for the exit lubricant temperature, power losses and floating ring speeds agree well with measurements obtained in an automotive turbocharger test rig. The rotordynamic stability characteristics of the test TC are also highlighted. NOTATIONa, b parameters in Vogel's equation A area for heat transfer (m 2 ) ¼ pDL c p lubricant specific heat (J/kg K) C bearing radial clearance (m) D bearing diameter (m) ¼ 2R e eccentricity vector ðe X , e Y Þ (m) FRB floating ring journal bearing F fluid film force ðF X , F Y Þ (N) h film thickness (m) H heat convection coefficient (W/m 2 K) I R ring mass moment of inertia (kg m 2 ) L bearing length (m) M mass (kg) } mechanical power (W) P hydrodynamic pressure (Pa) Pr Prandtl number ¼ c p m/k Q volumetric flowrate (m 3 /s) R radius (m) ¼ D/2 Re Reynolds number ¼ rORC/m TC turbocharger T temperature (8C) W external force ðW X , W Y Þ ( N) x, z circumferential and axial coordinate on the plane of the film, x ¼ Ry X, Y inertial coordinate system a thermal expansion coefficient (K À 1 ) g lubricant shear rate (m À 1 ) G torque (N m) DT temperature difference ðKÞ ¼ T À T S e dimensionless eccentricity ¼ e/C y angle (rad) ¼ x/R k lubricant thermal conductivity (W/m 2 K) m lubricant viscosity (N s/m 2 ) r lubricant density (kg/m 3 ) O rotational speed (rad/s) O ring speed ratio ¼ O R /O J The MS was

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“…For laminar flows, ReðC=RÞ 4 1, Colburn's analogy renders the convection coefficients H ¼ 3Pr 1=3 ðk=CÞ (see references [23,12] and [24] for details).…”

Section: Discussionmentioning

confidence: 99%

Thermal effects on the performance of floating ring bearings for turbochargers

Andrés

Kerth

2004

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…Experimental investigations on the ring-to-shaft speed ratio have, for instance, been carried out in [31,32]. The influence of thermal effects (inner and outer oil-film temperatures) on the ring-to-shaft speed ratio is discussed in [33,34]. The influence of oil-film cavita- tion induced by centrifugal forces on the ring-to-shaft speed ratio is examined in [35,36].…”

Section: Introductionmentioning

confidence: 98%

Oil whirl, oil whip and whirl/whip synchronization occurring in rotor systems with full-floating ring bearings

Schweizer

2009

Nonlinear Dyn

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High-speed rotors are often supported in floating ring bearings because of their good damping behavior. In contrast to conventional hydrodynamic bearings with a single oil film, full-floating ring bearings consist of two oil films: An inner and an outer oil film. As single oil-film bearings, full-floating ring bearings also show the typical fluid-film-induced instabilities (self-excited vibrations). Both inner and outer oil films can become unstable and exhibit oil whirl/whip instabilities.The paper at hand considers a Laval (Jeffcott) rotor, which is symmetrically supported in full-floating ring bearings, and investigates the occurring oil whirl/whip effects by means of run-up simulations. It is shown that the inner oil film, which usually becomes unstable first, gives rise to a limit-cycle oscillation with an exactly circular rotor orbit, if gravity and imbalance are neglected. Interesting is the instability generated by the outer oil film. The calculations demonstrate that instability in the outer oil film does not lead to a simple circular limit-cycle orbit. Whirl/whip-induced limit-cycle oscillations generated by the outer oil film are more complex and entail a coupled circumferential and radial motion, although the mechanical problem B. Schweizer ( )

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“…Thermal effect has long been assumed to be the cause of the decrease in speed ratio. 10–13 San Andres and Kerth 11 solve lumped energy equation with viscous heat generation and consider convective heat transfer between fluid and solid to predict the temperature-dependent viscosity.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of subsynchronous vibration in floating ring bearings

Wang

Ren

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part J:

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Floating ring bearings are popular among turbochargers due to their simplicity and reliability. The disappearance of subsynchronous vibration with the increase of shaft speed in a low oil-supplied pressure floating ring bearing is reported by Hatakenaka and Yanai. This finding may help eliminate the noise and decrease the loss of turbochargers. This work aims to explain this phenomenon in the low oil-supplied floating ring bearing using computational fluid dynamic. Steady computational fluid dynamic calculation is conducted to validate the effect of air entrainment. Transient computational fluid dynamic calculation method with mesh motion method is established. The subsynchronous vibration of the shaft can be obtained by discrete Fourier transform analysis. The results are validated by comparing them with those in the literature. It is found that the disappearance of the subsynchronous vibration is the result of the change in lubricant properties caused by the air entrainment.

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A Steady-State Model of a Floating Ring Bearing, Including Thermal Effects

Cited by 28 publications

References 0 publications

Thermal effects on the performance of floating ring bearings for turbochargers

Thermal effects on the performance of floating ring bearings for turbochargers

Oil whirl, oil whip and whirl/whip synchronization occurring in rotor systems with full-floating ring bearings

Numerical investigation of subsynchronous vibration in floating ring bearings

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