Dynamic Stiffness and Damping of Externally Pressurized Gas Lubricated Journal Bearings

Fleming, D. P.; Thayer, W. J.; Cunningham, Robert E.

doi:10.1115/1.3452954

Cited by 9 publications

(8 citation statements)

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“…(frequency) Damping, stiffness and 28 non-linear coefficients Tonnesen (1976) SQF Unbalance Displ. (frequency) Damping Fleming et al (1977) GJ Unbalance Displ. (frequency) Damping and stiffness Wright (1978) LS Impact Displ.…”

Section: Referencesmentioning

confidence: 99%

Identification of Dynamic Bearing Parameters: A Review

Tiwari¹,

Lees²,

Friswell³

2004

shock vib digest

133

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In this paper, we present a review of the experimental identification of dynamic parameters of bearings in a rotating machine. Major emphasis is given to vibration-based identification methods and the review encompasses descriptions of experimental measurement techniques, mathematical modeling, parameter extraction algorithms and uncertainty in the estimates applied to a variety of bearings. The parameter extraction algorithms include the descriptions of governing equations of the rotor-bearing system and identification methods in both time and frequency domains. The identification techniques have been classified based on methods used to excite the system. The review includes a variety of bearings and similar components, which play an active link between the rotating and stationary parts of a machine. Based on the state of the art in bearing identification, conclusions are made and future directions are suggested.

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Section: Referencesmentioning

confidence: 99%

Identification of Dynamic Bearing Parameters: A Review

Tiwari¹,

Lees²,

Friswell³

2004

shock vib digest

133

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“…where d o is the inner diameter of the ith feeding hole; c d is the discharge coefficient that depends on the orifice geometry, Reynolds number, and the film thickness, and it could be computed by the formula, which was proposed by Belforte et al 27 as given in equation (4). The orifice function, Φ, could be determined by equation (5):…”

Section: Theoretical Definitions and Mathematical Modelsmentioning

confidence: 99%

“…In other words, the dynamic of the shaft supported by the aerostatic bearing is directly related to this airflow, which depends on the structural specifications of the gap, operational conditions of the system (shaft speed and supply pressure), and feeding system parameters such as the structural properties of the feeding holes, number, and arrangement of holes. 3,4 Feeding of pressurized air to the bearing greatly influences the response of aerostatic bearings. Hence, aerostatic bearings have been theoretically and experimentally studied considering the effects of the feeding systems in many research studies.…”

Section: Introductionmentioning

confidence: 99%

Performance characteristics of an aerostatic journal bearing with partially blocked orifices

Dal

Karaçay

2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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Aerostatic journal bearing applications mainly focus on high-speed precision machining, so predictable and smooth functioning of the system is crucial. Air is supplied to the bearing through a number of orifices and any unevenness in the size of these orifices will affect the performance of the system. The size difference could be due to manufacturing error and/or blockage of the orifice because of foreign materials in the air system. In this study, the performance of an aerostatic bearing with a partially blocked orifice is numerically investigated. Firstly, the airflow in the bearing clearance was modeled with Reynolds equation and this equation was numerically solved with the finite difference and differential transform hybrid method to obtain the pressure distribution. Then, the force and the stiffness are calculated from the pressure distribution for different blockage cases of the orifice and different blockage ratios. The results show that the partial blockage of the orifice significantly changes the performance of the system in a positive or a negative way according to the feeding hole position, and the blockage ratio also affects performance.

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“…4 In many studies, the whirl and whip instability problems were investigated theoretically and experimentally in detail. [5][6][7][8][9] Su and Lie 10 studied the whirl instability of the shaft with aerostatic bearing, which have different types of feeding system. Zhang et al 11 numerically investigated the stability and bifurcation characteristics of rigid rotor with an air journal bearing.…”

Section: Introductionmentioning

confidence: 99%

Pneumatic hammer instability in the aerostatic journal bearing–rotor system: A theoretical and experimental analyses

Dal

Karaçay

2020

Proceedings of the Institution of Mechanical Engineers, Part J:

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In this study, the pneumatic hammer instability phenomena in the aerostatic journal bearing–rotor system is analysed and discussed for different feeding hole configurations theoretically and experimentally. The influences of the configuration of the feeding holes on the nonlinear dynamics of the system are also investigated. The air flow between the surfaces is modelled with Reynold’s equation and it is numerically solved with differential transform and finite difference hybrid method. Three different aerostatic bearings are modelled and simulated to investigate the ınfluences of the configuration of the holes for different angular speeds. An experimental test rig is designed and tested for different rotor speeds to validate the obtained numerical results. The dynamic response of the system is analysed using waterfall plots, bifurcation diagrams, orbit plots, phase portrait and Poincaré map, which are drawn to determine the pneumatic hammer instability region of the modelled system. The results reveal a nonlinear dynamic response of the rotor centre. In addition, the analysis shows that the feeding hole configuration affects the rotor dynamics and the pneumatic hammer instability region.

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Dynamic Stiffness and Damping of Externally Pressurized Gas Lubricated Journal Bearings

Cited by 9 publications

References 0 publications

Identification of Dynamic Bearing Parameters: A Review

Identification of Dynamic Bearing Parameters: A Review

Performance characteristics of an aerostatic journal bearing with partially blocked orifices

Pneumatic hammer instability in the aerostatic journal bearing–rotor system: A theoretical and experimental analyses

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