A review on machinery diagnostics and prognostics implementing condition-based maintenance

Artificial intelligence for fault diagnosis of rotating machinery: A review

Vibration of cracked structures: A state of the art review

Recent advances in time–frequency analysis methods for machinery fault diagnosis: A review with application examples

Residual life predictions for ball bearings based on self-organizing map and back propagation neural network methods

A computational methodology is proposed to predict the running clearance of a six-tooth straight-through rotating labyrinth seal numerically by taking into account both the centrifugal and thermal growths. Four different angular velocities ranging from 0 to 3000 rad/s are chosen to study the influence of rotation on the leakage flow rate. The detailed leakage flow fields and the structural deformations are presented. Further, different pressure ratios in the range of 1.1 to 2.5 have been investigated for a wide range of initial clearances. The methodology is validated against the available data in the literature. It is found out that there is a significant reduction in leakage flow rate by incorporating the radial growth for a particular operating condition. However, for a given initial clearance, the rotation has negligible effect on the reduction in the leakage flow rate, except at pressure ratios lower than 1.7. Further; the rotation has more prominent effect for smaller clearance values.Copyright © 2013 by ASME

Performance Analysis of a Rotating Labyrinth Seal With Radial Growth

Rotors today are made highly flexible with ever increasing demand for higher speeds, and it is important to predict the rotor dynamic behaviour accurately. Supports play an important role and influence the magnitude of vibration in response to external forces. In the present study, frequency dependent polymeric support characteristics have been found by using a multi objective optimisation scheme for minimising the unbalanced response and maximising the stability limit speed. This is an improvement over the previous papers where a simple equally weighted sum of two objective functions was used. A novel hybrid of particle swarm optimisation (PSO) and augmented Lagrangian has been used here to find the global minima. Using appropriate constraints, the slope of the support characteristics versus frequency is restricted to realistic values. Rotor systems with rolling element bearings and plain cylindrical journal bearings are studied using this approach and higher stability limits are obtained.

Multi-objective optimisation of support characteristics of rotor bearing systems

Rotor shafts subjected to severe operating stresses are prone to develop transverse fatigue cracks at the localized stress raisers. Therefore, the ability to identify and locate the incipient fatig...

Detection and localization of fatigue-induced transverse crack in a rotor shaft using principal component analysis:

Usually while modelling rotor-bearing systems the bearings are treated as point supports. In the present paper, using the finite element technique, the unbalance response of rotors is studied by considering distributed bearing stiffness and damping. The bearing stiffness and damping terms are derived by the principle of virtual work. Unbalance responses of rotors with bearing distributed effects are compared with the model using point supports and for different supports Viz., cylindrical journal bearings, tilting pad journal bearings, offset and three lobe journal bearings.Copyright © 1994 by ASME

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Unbalance Response of Rotors Considering the Distributed Bearing Stiffness and Damping

Abstract Radial growth predictions of rotating labyrinth seals are conventionally obtained from one-dimensional analytical models. However, these predictions quantitatively differ within themselves by about 5-500 %. Simulations using three-dimensional finite element method (FEM) are carried out in this paper for a typical labyrinth seal, subjected to high rotational speed and temperature, for a range of radius-to-length ratio of the rotor. Taking the predicted values by FEM as reference, four analytical models are assessed and their errors are quantified. These errors are found to be independent of rotational speed and temperature but significantly vary with the radius-to-length ratio of the rotor. Based on this finding, simple analytical models, together with correction factor charts, are suggested.

A. S. Sekhar

Papers

Performance Analysis of a Rotating Labyrinth Seal With Radial Growth

Multi-objective optimisation of support characteristics of rotor bearing systems

Detection and localization of fatigue-induced transverse crack in a rotor shaft using principal component analysis:

Unbalance Response of Rotors Considering the Distributed Bearing Stiffness and Damping

Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals