Analysis of deceleration phenomenon of high speed rotor systems
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.
About: This article is published in Mechanical Systems and Signal Processing.The article was published on 1987-07-01. It has received 7 citations till now. The article focuses on the topics: Rotor (electric).
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TL;DR: In this paper, the authors used the continuous wavelet transform (CWT) to extract sub-harmonics from the time domain signals of a rotor system coasting down through its critical speed.
23 citations
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
TL;DR: In this paper, the authors re-examine the classical machinery shut down vibration problem in the context of a two degree of freedom nonlinear torsional system that essentially describes a braking system example.
19 citations
Additional excerpts
...Similar observations regarding the peak amplitude levels and the speeds at which they occur have been made for both linear [3,4] and nonlinear [5] mechanical systems....
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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 Article•
TL;DR: In this article, the authors used the coast-down time (CDT) to detect the defects of the shaft assembly and found that the speed decay pattern followed a second order fitting of percentage speed reduction as a function of time.
Abstract: Rotating equipment under the action of dynamic forces, are prone to defects, such as misalignment, unbalance, change of rotor slope, skewed bearings, etc. These defects, if ignored for prolonged periods can cause sudden outages that may have serious consequences. Therefore, application of an appropriate condition monitoring technique is desirable to assess the health of the equipment and plan its maintenance. In this paper, monitoring of coast-down time (CDT) is undertaken to meet the objective. The CDT is the time elapsed between the instant the power is switched off to the rotor system till it comes to rest. The work demonstrates that, the CDT does detect the defects of the shaft assembly. Experiments were conducted on a specifically fabricated rig. The results revealed that the speed decay pattern followed a second order fitting of percentage speed reduction as a function of time. Defect identification parameter (DIP) is defined, which is a ratio of the polynomial coefficients of the first and the second order terms. The DIP values were found to correlate uniquely with the unbalance and the radial off-set defects in the shaft assembly.
4 citations
Cites background from "Analysis of deceleration phenomenon..."
...[10] studied the relationship of unbalance and damping on deceleration during the coast down....
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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.
9 citations
TL;DR: In this paper, the problem of single-degree-of-freedom rotor decelerating slowly through its critica speed is solved by an energy approach; a closed solution is obtained.
Abstract: The problem of a single-degree-of-freedom rotor decelerating slowly through its critica speed is solved by an energy approach; a closed solution is obtained. A small discontinuous downward jump of rotor speed across the critical speed is shown to be required, either with or without damping in the system. The maximum increment of deflection, hence bending stress, in the rotor shaft is shown to be small, provided the rotor is carefully balanced and/or the system is sufficiently damped.
4 citations