Coupling of Rotor-Gear-Casing Vibrations During Extreme Operating Events

1992 ◽  
Vol 114 (4) ◽  
pp. 464-471 ◽  
Author(s):  
F. K. Choy ◽  
J. Padovan ◽  
Y. F. Ruan
Keyword(s):  
Element Model ◽  
Operating Conditions ◽  
Transient Vibration ◽  
Rotor Systems ◽  
Power Plant Equipment ◽  
Modal Synthesis ◽  
Operating Environments ◽  
Rotor Bearing ◽  
The Matrix ◽  
Plant Equipment

During extreme operating environments (i.e., seismic events, base motion-induced vibrations, etc.), the coupled vibrations developed between the rotors, bearings, gears and enclosing structure of gear-driven rotating equipment can be quite substantial. Generally, such large vibrational amplitudes may lead to failures in both the rotor-gearing system and/or the casing structure. This paper simulates the dynamic behavior of rotor-bearing-gear system resulting from motion of the enclosed structure. The modal synthesis approach is used in this study to synthesize the dynamics of the rotor systems with the vibrations of their casing structure in modal coordinates. Modal characteristics of the rotor-bearing-gear systems are evaluated using the matrix transfer technique, while the modal parameters for the casing structure are developed through a finite element model using NASTRAN. The modal accelerations calculated are integrated through a numerical algorithm to generate modal transient vibration analysis. Vibration results are examined in both time and frequency domains to develop representations for the coupled dynamics generated during extreme operating conditions. Typical three-rotor bull gear-driven power plant equipment (compressors, pumps, etc.) is used as an example to demonstrate the procedure developed.

scholarly journals Modal Analysis of Multistage Gear Systems Coupled With Gearbox Vibrations

1992 ◽  
Vol 114 (3) ◽  
pp. 486-497 ◽  
Author(s):  
F. K. Choy ◽  
Y. F. Ruan ◽  
R. K. Tu ◽  
J. J. Zakrajsek ◽  
D. P. Townsend
Keyword(s):  
Synthesis Method ◽  
Coupled System ◽  
Element Model ◽  
Integration Scheme ◽  
Transient Vibration ◽  
Gear Mesh ◽  
Time Stepping ◽  
Modal Synthesis ◽  
Rotor Bearing ◽  
The Matrix

This paper presents an analytical procedure to simulate vibrations in gear transmission systems. This procedure couples the dynamics of the rotor-bearing gear system with the vibration in the gearbox structure. The modal synthesis method is used in solving the overall dynamics of the system, and a variable time-stepping integration scheme is used in evaluating the global transient vibration of the system. Locally each gear stage is modelled as a multimass rotor-bearing system using a discrete model. The modal characteristics are calculated using the matrix-transfer technique. The gearbox structure is represented by a finite element model, and modal parameters are solved by using NASTRAN. The rotor-gear stages are coupled through nonlinear compliance in the gear mesh while the gearbox structure is coupled through the bearing supports of the rotor system. Transient and steady state vibrations of the coupled system are examined in both time and frequency domains. A typical three-geared system is used as an example for demonstration of the developed procedure.

Paper 11: Feed Pumps for Modern Steam Boiler Applications, Design, Development, and Operation

1969 ◽  
Vol 184 (14) ◽  
pp. 108-148
Author(s):  
P. S. Neporozhnii ◽  
A. K. Kirsh
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Operating Conditions ◽  
Steam Boiler ◽  
Design Development ◽  
Feed Pump ◽  
Design Features ◽  
Power Plant Equipment ◽  
Plant Equipment

This paper describes the operating conditions which form the basis for determining the various types of feed pump units needed to equip the main power plant equipment in the U.S.S.R. The principles upon which the feed pump groups are selected, according to the type of equipment installed in different power plants, are considered. The system diagrams and design features of the feed pumps are presented, together with descriptions of how they are driven.

scholarly journals A Novel Method for the Dynamic Coefficients Identification of Journal Bearings Using Kalman Filter

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 565 ◽  
Author(s):  
Yang Kang ◽  
Zhanqun Shi ◽  
Hao Zhang ◽  
Dong Zhen ◽  
Fengshou Gu
Keyword(s):  
Kalman Filter ◽  
High Efficiency ◽  
Resonance Condition ◽  
Experimental Tests ◽  
Element Model ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Dynamic Coefficients ◽  
Rotor Bearing ◽  
Coefficients Identification

The dynamic coefficients identification of journal bearings is essential for instability analysis of rotation machinery. Aiming at the measured displacement of a single location, an improvement method associated with the Kalman filter is proposed to estimate the bearing dynamic coefficients. Firstly, a finite element model of the flexible rotor-bearing system was established and then modified by the modal test. Secondly, the model-based identification procedure was derived, in which the displacements of the shaft at bearings locations were estimated by the Kalman filter algorithm to identify the dynamic coefficients. Finally, considering the effect of the different process noise covariance, the corresponding numerical simulations were carried out to validate the preliminary accuracy. Furthermore, experimental tests were conducted to confirm the practicality, where the real stiffness and damping were comprehensively identified under the different operating conditions. The results show that the proposed method is not only highly accurate, but also stable under different measured locations. Compared with the conventional method, this study presents a more than high practicality approach to identify dynamic coefficients, including under the resonance condition. With high efficiency, it can be extended to predict the dynamic behaviour of rotor-bearing systems.

On the Transient Analysis of Rotor-Bearing Systems

1988 ◽  
Vol 110 (4) ◽  
pp. 515-520 ◽  
Author(s):  
R. Subbiah ◽  
N. F. Rieger
Keyword(s):  
Dynamic Systems ◽  
Transient Analysis ◽  
Element Model ◽  
Flexible Rotor ◽  
Rotor Systems ◽  
Response Data ◽  
Rotor Bearing ◽  
Time Marching ◽  
The Stability ◽  
The Given

The transient dynamic response of a flexible rotor in nonlinear supports has been investigated using time marching methods. Several marching techniques such as Newmark β, Wilson θ, and Houbolt have been utilized in this study of rotor-bearing dynamic systems, to examine the stability of the system, and the suitability of each technique for predicting the onset of instability. The given rotor system has been modeled both in space and time using the transfer matrix method and the Houbolt method. The transient orbital response data so obtained have been compared with those obtained by a finite element model. Differences in the order of 6 percent were found. A nonlinear representation of a finite bearing has been included in the transient matrix model and the stability characteristics of different rotor systems of varied complexity have been studied. The nonlinear results have been compared with earlier results obtained using linear bearing representations.

Nonlinear Flutter Response of Tilting 4 Pad Bearings-Rotor System

2011 ◽  
Author(s):  
Jiayang Ying ◽  
Yinghou Jiao ◽  
Zhaobo Chen ◽  
R. Gordon Kirk
Keyword(s):  
Transient Vibration ◽  
Oil Film ◽  
Rotor Systems ◽  
Tilting Pad ◽  
Jeffcott Rotor ◽  
Rotor Bearing ◽  
Nonlinear Transient ◽  
Rotor Center ◽  
Design Speed ◽  
Tilting Pad Journal Bearing

Nonlinear analysis is increasingly applied in the dynamics analysis of rotor bearing systems. The use of tilting-pad bearings is now a standard feature of many types of rotor systems. The concern for oil film excitation of the rotor lowest natural frequency is eliminated by the use of the tilting pad journal bearings. For new higher speed or larger low speed applications, the possibility of the pad flutter instability still remains and most commonly used design tools do not consider the pad inertia as a standard feature. In this paper, taking the Jeffcott rotor supported by two 4 pad bearings as an example, the influence of pad inertia and journal diameter were studied. The influence of shaft diameter and pad inertia was determined by the transient response of a simple rotor-bearing system operating over a wide design speed range. The tilting pad journal bearing oil-film force was calculated by a database method. The resulting nonlinear transient vibration is discussed using bifurcation diagrams, orbits, frequency spectrum plots, phase trajectories, and Poincare maps. The results directly show that journal diameter and pad inertia greatly influence the nonlinear vibrations of the journal and rotor center.

NICROFER 6023

Alloy Digest ◽  
1985 ◽  
Vol 34 (5) ◽  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Iron Alloy ◽  
Heat Treating ◽  
Chemical Equipment ◽  
Good Resistance ◽  
Nickel Chromium ◽  
Power Plant Equipment ◽  
Resistance To Oxidation ◽  
Plant Equipment

Abstract NICROFER 6023 is a nickel-chromium-iron alloy containing small quantities of aluminum. It has excellent resistance to oxidation at high temperatures, good resistance in oxidizing sulfur-bearing atmospheres and good resistance to carburizing conditions. The alloy has good mechanical properties at room and elevated temperatures. Its applications include heat treating furnace equipment, chemical equipment in various industries, and power plant equipment. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-314. Producer or source: Vereingte Deutsche Metallwerke AG.

scholarly journals Core Stress Analysis of Amorphous Alloy Transformer for Rail Transit under Different Working Conditions

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 164
Author(s):  
Jianwei Shao ◽  
Cuidong Xu ◽  
Ka Wai Eric Cheng
Keyword(s):  
Amorphous Alloy ◽  
Working Conditions ◽  
Short Circuit ◽  
Element Model ◽  
Operating Conditions ◽  
Iron Core ◽  
Rail Transit ◽  
Transit System ◽  
The Core ◽  
Distribution Transformers

The rail transit system is a large electric vehicle system that is strongly dependent on the energy technologies of the power system. The use of new energy-saving amorphous alloy transformers can not only reduce the loss of rail transit power, but also help alleviate the power shortage situation and electromagnetic emissions. The application of the transformer in the field of rail transit is limited by the problem that amorphous alloy is prone to debris. this paper studied the stress conditions of amorphous alloy transformer cores under different working conditions and determined that the location where the core is prone to fragmentation, which is the key problem of smoothly integrating amorphous alloy distribution transformers on rail transit power supply systems. In this study, we investigate the changes in the electromagnetic field and stress of the amorphous alloy transformer core under different operating conditions. The finite element model of an amorphous alloy transformer is established and verified. The simulation results of the magnetic field and stress of the core under different working conditions are given. The no-load current and no-load loss are simulated and compared with the actual experimental data to verify practicability of amorphous alloy transformers. The biggest influence on the iron core is the overload state and the maximum value is higher than the core stress during short circuit. The core strain caused by the side-phase short circuit is larger than the middle-phase short circuit.

Theoretical analysis of a rolling-sliding elastohydrodynamic lubrication line contact with a subsurface inclusion

2019 ◽  
Vol 233 (8) ◽  
pp. 1197-1207
Author(s):  
Armando Félix Quiñonez ◽  
Guillermo E Morales Espejel
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Element Model ◽  
Von Mises Stress ◽  
Transient Effects ◽  
Mean Velocity ◽  
The Matrix ◽  
Soft Inclusion ◽  
The Mean ◽  
Von Mises ◽  
Fully Coupled

This work investigates the transient effects of a single subsurface inclusion over the pressure, film thickness, and von Mises stress in a line elastohydrodynamic lubrication contact. Results are obtained with a fully-coupled finite element model for either a stiff or a soft inclusion moving at the speed of the surface. Two cases analyzed consider the inclusion moving either at the same speed as the mean velocity of the lubricant or moving slower. Two additional cases investigate reducing either the size of the inclusion or its stiffness differential with respect to the matrix. It is shown that the well-known two-wave elastohydrodynamic lubrication mechanism induced by surface features is also applicable to the inclusions. Also, that the effects of the inclusion become weaker both when its size is reduced and when its stiffness approaches that of the matrix. A direct comparison with predictions by the semi-analytical model of Morales-Espejel et al. ( Proc IMechE, Part J: J Engineering Tribology 2017; 231) shows reasonable qualitative agreement. Quantitatively some differences are observed which, after accounting for the semi-analytical model's simplicity, physical agreement, and computational efficiency, may then be considered as reasonable for engineering applications.

Effect of Interfacial Properties on the Mechanical Behavior of Bone-Like Materials: A Numerical Study

2017 ◽  
Vol 09 (01) ◽  
pp. 1750014 ◽  
Author(s):  
Xingguo Li ◽  
Bingbing An ◽  
Dongsheng Zhang
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Numerical Study ◽  
Element Model ◽  
Interfacial Behavior ◽  
Yield Behavior ◽  
Bonding Property ◽  
The Matrix ◽  
Bonding Properties ◽  
Superior Mechanical Properties

Interfacial behavior in the microstructure and the plastic deformation in the protein matrix influence the overall mechanical properties of biological hard tissues. A cohesive finite element model has been developed to investigate the inelastic mechanical properties of bone-like biocomposites consisting of hard mineral crystals embedded in soft biopolymer matrix. In this study, the complex interaction between plastic dissipation in the matrix and bonding properties of the interface between minerals and matrix is revealed, and the effect of such interaction on the toughening of bone-like biocomposites is identified. For the case of strong and intermediate interfaces, the toughness of biocomposites is controlled by the post yield behavior of biopolymer; the matrix with low strain hardening can undergo significant plastic deformation, thereby promoting enhanced fracture toughness of biocomposites. For the case of weak interfaces, the toughness of biocomposites is governed by the bonding property of the interface, and the post-yield behavior of biopolymer shows negligible effect on the toughness. The findings of this study help to direct the path for designing bioinspired materials with superior mechanical properties.

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