Experiments on the Stability of an Overhung Rotor in Pressure-Dam and Multilobe Bearings

Zuck, C. J.; Flack, Ronald D.

doi:10.1080/05698198708981752

Cited by 8 publications

(4 citation statements)

References 16 publications

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“…Compared to the current isoviscous analysis, the inclusion of the thermal effects tends to increase the journal operating eccentricity, decrease the stiffness and damping coefficients, and decrease the rigid rotor stability threshold speeds. As an example, the adiabatic analysis also improves the stability prediction for the rotor/bearing system in reference (19). While the pressure distribution is similar to those obtained in previous studies, the temperature distribution shows three distinct regions, implying that the two-dimensional equation that assumes constant axial temperature profile cannot be applied to a pressure dam pad.…”

Section: Discussionsupporting

confidence: 54%

A Pressure Dam Bearing Analysis with Adiabatic Thermal Effects©

Allaire

Cloud

et al. 2004

Tribology Transactions

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Section: Discussionsupporting

confidence: 54%

A Pressure Dam Bearing Analysis with Adiabatic Thermal Effects©

Allaire

Cloud

et al. 2004

Tribology Transactions

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“…Thus, one bearing design is not necessarily the best from the perspective of stability and unbalance response [15]. Zuck and Flack [16], in their work on overhung rotor in a preloaded three-lobe bearing, found that large preloads were again advantageous. Ma and Taylor [17] presented a theoretical evaluation of the steady-state performance of different fixed profile bearings with the consideration of thermal effects.…”

Section: Introductionmentioning

confidence: 99%

Preload effects on the static performance of multi-lobe fixed profile journal bearings with micropolar fluids

Rahmatabadi

Meybodi

Nekoeimehr

2011

Proceedings of the Institution of Mechanical Engineers, Part J:

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The performance of non-circular bearings, such as multi-lobe bearings is influenced by many bearing parameters such as the number of lobes, the preload factor, and the tilt angle. In this study, the effects of bearing preload factor on the static performance characteristics of micropolar lubricated two-, three-, and four-lobe bearings are investigated. For this purpose, modified Reynolds equation for micropolar fluids is solved by FEM, to find the fluid film pressure. Then, in turn, bearing performance characteristics, namely, load-carrying capacity, attitude angle, frictional force, friction coefficient, and side leakage flow are calculated. Results show that, in general, micropolarity of the lubricant improves the performance of the bearings; however, non-circularity parameter of the lobe of the bearings, preload, has a favourable effect on certain performance characteristics of the bearings, such as the attitude angle which decreases as non-circularity of the bearing increases. The results further show that the rate of influence of preload factor on the performance characteristics of different lobed bearings is not the same.

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“…T h e rotor and instrumentation were fully described in (19). For the sake of brevity only the important details will be reviewed herein.…”

Section: Rotor and Bearingsmentioning

confidence: 99%

Experiments and Stability Predictions of Two Sets of Tilting Pad Bearings on an Overhung Rotor

Zuck

Flack

Knight

et al. 1988

Tribology Transactions

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Avr overl~~cng rotor was experimentally tested i n two sets of five shoe tilling pail 6enrings. The preload factors of the two sets were 0.1 rriid 0.5, respectively. The rotor had critical speeds at 3 0 0 0 nni16800 I p~n When mounted on the Jirst set of bearings, the rotor re~tu~ineil .stnOleJi)r speeds over I 1 000 rpm. However, when mounted i n the second set i f be(~ring~s the system went unstable due to whip irt 1 0 4 0 0 rpm. A ttieoretical ana1y.si.s was performed on the stability rf the mtor system to determine f the bearings were the cause of ttic wl~ip. Tire nnnlysis indicc~tes thal the system is margznally stable, the bearing design. T h e load carrying capacity is also affected by the design parameters.A typical five shoe tilting pad bearing is shown in Fig. 1. Each pad has a radius of curvature Rp, which is not necessarily equal to the nominal bearing radius Rb. If Rp is larger than Rb, which is usually the case, the bearing is said to be positively preloaded since each pad when centered forms a converging-diverging wedge which generates a hydrodynamic load. T h e preload factor m is defined as: n,id thnt SIIL(LII cro.s.s couplings generuled by the disk-shaft mountings m = 1 -cbl(Ry -R ) rlestnbilized tlie system. Also, pad inertia has little affect on the [I1 stn0ility cf this pnrticular rotor. The system was predicted to be the Another important parameter is the offset factor a which most stable when ~r~ounted on the bearings with a preload of 0.1, is defined as: so tlrc~t the j)redicted trends with varying preload were correct. The prc!dictiol~s c~lso indicnte that subsynchronozlsly reduced bearing a = PIX 121 coiflicicnts ( a s opposed to syncttronously reduced coefficients) sliould be ii.sail i n .stobilily nnelyses.

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Experiments on the Stability of an Overhung Rotor in Pressure-Dam and Multilobe Bearings

Cited by 8 publications

References 16 publications

A Pressure Dam Bearing Analysis with Adiabatic Thermal Effects©

A Pressure Dam Bearing Analysis with Adiabatic Thermal Effects©

Preload effects on the static performance of multi-lobe fixed profile journal bearings with micropolar fluids

Experiments and Stability Predictions of Two Sets of Tilting Pad Bearings on an Overhung Rotor

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