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Journal ArticleDOI

An experimental investigation of tribological effects on coastdown phenomena in horizontal rotating machinery

15 Oct 1983-Wear (Elsevier)-Vol. 91, Iss: 1, pp 25-31
TL;DR: In this article, the authors investigated the coastdown characteristics of a two-rotor system consisting of a variable-speed d.c. motor driving a flexible rotor on two journal bearings.
About: This article is published in Wear.The article was published on 1983-10-15. It has received 9 citations till now. The article focuses on the topics: Rotor (electric).
Citations
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Journal ArticleDOI
TL;DR: In this paper, the experimental performance of misaligned cylindrical and three-lobe journal bearings was evaluated using a double-disc rotor system with a test bearing in the middle and driven by a variable speed DC motor through an electromagnetic coupling.
Abstract: In this paper an investigation is made to evaluate the experimental performance of misaligned cylindrical and three-lobe journal bearings. A three-bearing double-disc rotor system with a test bearing in the middle and driven by a variable speed DC motor through an electromagnetic coupling is used. Various parameters which have been studied are friction through coastdown analysis, unbalance response and film thickness. The system damping also has been evaluated. The film thickness decreases, friction increases and system damping increases as the bearing misalignment increases. While the first, third and fourth harmonics vibration response is found to be almost steady with a increasing degree of misalignment, the second harmonics vibration response tends to decrease slightly. Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Francisco, California, October 13–17, 1996

29 citations

Journal ArticleDOI
01 May 1997-Wear
TL;DR: In this paper, an investigation has been made to evaluate experimentally the performance characteristics of a misaligned 3-lobe journal bearing, and various parameters which have been studied are: friction through coast down time analysis, vibration responses, minimum film thickness, stiffness and damping coefficients of the fluid film, system natural frequency and the damping factor.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present both theoretical and experimental analysis of a four-pad tilting pad journal bearing, including the simultaneous solution of Reynolds equation, energy equation and deformation equation.
Abstract: Thermal and elastic effects play a very important role in lubrication of tilting pad journal bearings. This paper presents both theoretical and experimental analysis of tilting pad journal bearing. Theoretical analysis includes the simultaneous solution of Reynolds equation, energy equation and deformation equation. The computer code has been developed based on FEM which will work for large number of pads. Experimental study has been carried out on a four-pad tilting pad journal bearing, load between pad configuration and load on pad configurations with the rotational speed varied from 500-4000 rpm. Twelve thermocouples are used to measure pad temperatures. Coastdown time analysis results are presented in the form of Stribeck diagram of friction and compared with theoretical ones. Theoretical results are presented for steady-state and dynamic-state conditions of a four-pad tilting pad journal bearing. Presented as a Society of Tribologists and Lubrication Engineers paper at the World Tribology Congress in...

22 citations

Journal ArticleDOI
30 Nov 1997-Wear
TL;DR: In this article, an experimental investigation has been carried out on the steady state and dynamic performance characteristics of a tilting pad journal bearing, which has been made using a thermocouple measuring system.

13 citations

Journal ArticleDOI
TL;DR: In this paper, the problem of decelerating a rotor from a high speed through its critical speeds has received very little attention in technical literature although transient processes occurring during coastdown of machinery usually provide a lot of information about their tribodynamics.

7 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the onset and development of wear in plain hydrodynamic journal bearings under repeated cycles of starting and stopping has been studied experimentally and it was found that the wear caused easily discernable but localized changes in diametral clearance, surface finish, and roundness of the bearing's bore.
Abstract: The onset and development of wear in plain hydrodynamic journal bearings under repeated cycles of starting and stopping has been studied experimentally. The wear which occurred caused easily discernable but localized changes in diametral clearance, surface finish, and roundness of the bearing's bore and these changes were measured after various numbers of operating cycles had been completed. Study of the location, within the bearings of the wear which arose, showed that it was caused entirely by the sliding which occurred during starting and that no significant contribution to the wearing process was made during stopping. It was also observed that, once an initial rapid phase of wearing was completed, the surface finish of the hardened steel shaft was reproduced in the regions of the bearing's surface which continued to be worn.

51 citations

Journal ArticleDOI
TL;DR: In this article, the behavior of plain, hydrodynamic journal bearings during starting and stopping under a steady load was investigated and the starting behavior indicated that a rapid buildup of hydrodynamynamic forces occurred in all cases.
Abstract: The work described is concerned with the behavior of plain, hydrodynamic journal bearings during starting and stopping under a steady load. The starting behavior indicated that a rapid buildup of hydrodynamic forces occurred in all cases. A hydrodynamic film was formed in a very short time, after which the shaft moved in a spiral shaped whirling locus to the steady state operating position. Prior to separation of the shaft and bearing surfaces, the contact was mainly a sliding situation with little or no initial rolling. At stopping, the shaft followed a typical hydrodynamic locus until rotation ceased and then a squeeze film trajectory to the final resting position.

32 citations

Journal ArticleDOI
TL;DR: In this article, a technique was presented to assess the mechanical condition of vertical axis electric motors equipped with grease-lubricated ball bearings by comparing observed and predicted rotor coastdown times.
Abstract: A technique is presented to assess the mechanical condition of vertical axis electric motors equipped with grease-lubricated ball bearings by comparing observed and predicted rotor coastdown times. A theoretical expression for calculating the coastdown time required, as input, a relationship between rotor torque and rotational speed. Torque values derived from existing theory in the literature proved unsatisfactory. Experiments were conducted on four electric motors with varying bearing size and preload, blade configuration and grease lubricant properties to refine the input criteria. Substitution of these empirically derived torque values into the expression then gave acceptable results. Deviation of actual coastdown times from those predicted indicates a probable mechanical problem and need for investigation. Presented at the 33rd Annual Meeting in Dearborn, Michigan, April 17–20, 1978

11 citations