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Keywords: journal bearings, rotor, wear, wear identification, wear rate.

Summary

Journal bearings in rotating machines typically include at least two members which move relative to each other. During the operation of the machine, these members progressively wear down. To prevent catastrophic failure, it is necessary to detect exactly which components are worn out and require replacement. Unfortunately, detecting and evaluating the extent of wear upon the bearing members requires dismantling of the machine, physical inspection and relevant dimensional analysis, procedure that is time consuming and expensive.

The main objective here is to investigate that operational measurable and monitored characteristic could be used, for wear assessment in bearings without stopping the machine. Such characteristics could be the eccentricity ratio, the oil side flow rate, the attitude angle and the friction coefficient. Some of the above parameters or combinations of them are used in order to estimate, this way indirectly, the wear of the bearing.

Computational fluid dynamics (CFD) analysis, using FLUENT is used to solve the Navier-Stokes applicable to the lubrication problem. The bearing is considered as intact and worn using the well known Dufrane model [1]. Diagrams of relative eccentricity, lubricant side flow, bearing attitude angle and friction coefficient versus Sommerfeld number are presented for various wear depth. A graphical detection method based on the accurately, online, measurements of the bearing characteristics is used to detect the wear percentage.

With the proposed method the identification and the progress of the wear rate (gradual loss of material [2] of the bearing bush) can be calculated without dismantling the machine and the progress of the wear in the time domain can be very accurately estimated.

References

1: K.F. Dufrane, J.W. Kannel, T.H. McCloskey, "Wear Of Steam Turbine Journal Bearings At Low Operating Speeds", Journal of Lubrication Technology, 105(3),313-317, 1983.
2: B. Bhushan, "Principles and Applications of Tribology", Wiley, New York etc., 1999.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 120 Wear Identification in Rotor-Bearing Systems by Volumetric and Bearing Performance Characteristics Measurements K.P. Gertzos, P.G. Nikolakopoulos, A.C. Chasalevris and C.A. Papadopoulos Machine Design Laboratory, Department of Mechanical Engineering and Aeronautics, University of Patras, Greece doi:10.4203/ccp.88.120 purchase the full-text of this paper Full Bibliographic Reference for this paper K.P. Gertzos, P.G. Nikolakopoulos, A.C. Chasalevris, C.A. Papadopoulos, "Wear Identification in Rotor-Bearing Systems by Volumetric and Bearing Performance Characteristics Measurements", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 120, 2008. doi:10.4203/ccp.88.120 Keywords: journal bearings, rotor, wear, wear identification, wear rate. Summary Journal bearings in rotating machines typically include at least two members which move relative to each other. During the operation of the machine, these members progressively wear down. To prevent catastrophic failure, it is necessary to detect exactly which components are worn out and require replacement. Unfortunately, detecting and evaluating the extent of wear upon the bearing members requires dismantling of the machine, physical inspection and relevant dimensional analysis, procedure that is time consuming and expensive. The main objective here is to investigate that operational measurable and monitored characteristic could be used, for wear assessment in bearings without stopping the machine. Such characteristics could be the eccentricity ratio, the oil side flow rate, the attitude angle and the friction coefficient. Some of the above parameters or combinations of them are used in order to estimate, this way indirectly, the wear of the bearing. Computational fluid dynamics (CFD) analysis, using FLUENT is used to solve the Navier-Stokes applicable to the lubrication problem. The bearing is considered as intact and worn using the well known Dufrane model [1]. Diagrams of relative eccentricity, lubricant side flow, bearing attitude angle and friction coefficient versus Sommerfeld number are presented for various wear depth. A graphical detection method based on the accurately, online, measurements of the bearing characteristics is used to detect the wear percentage. With the proposed method the identification and the progress of the wear rate (gradual loss of material [2] of the bearing bush) can be calculated without dismantling the machine and the progress of the wear in the time domain can be very accurately estimated. References 1 K.F. Dufrane, J.W. Kannel, T.H. McCloskey, "Wear Of Steam Turbine Journal Bearings At Low Operating Speeds", Journal of Lubrication Technology, 105(3),313-317, 1983. 2 B. Bhushan, "Principles and Applications of Tribology", Wiley, New York etc., 1999. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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