Influence of axial thrust bearing defects on the dynamic behavior of an elastic shaft

2000 ◽  
Vol 33 (3-4) ◽  
pp. 153-160 ◽  
Author(s):  
Sébastien Berger ◽  
Olivier Bonneau ◽  
Jean Frêne
Keyword(s):  
Dynamic Behavior ◽  
Thrust Bearing ◽  
Axial Thrust ◽  
Elastic Shaft ◽  
Bearing Defects

Influence of Axial Thrust Bearing on the Dynamic Behavior of an Elastic Shaft: Coupling Between the Axial Dynamic Behavior and the Bending Vibrations of a Flexible Shaft

2000 ◽  
Vol 123 (2) ◽  
pp. 145-149 ◽  
Author(s):  
Se´bastien Berger ◽  
Olivier Bonneau ◽  
Jean Fre^ne
Keyword(s):  
Finite Elements ◽  
Dynamic Behavior ◽  
Axial Load ◽  
Thrust Bearing ◽  
Time Integration ◽  
Journal Bearings ◽  
Bending Vibrations ◽  
Axial Thrust ◽  
Flexible Shaft ◽  
Bearing Behavior

This paper presents the nonlinear dynamic behavior of a flexible shaft. The shaft is mounted in two journal bearings and the axial load is supported by a hydrodynamic thrust bearing. The coupling between the axial thrust bearing behavior and the bending vibrations of the shaft is studied in particular. The shaft is modeled with typical beam finite elements. The dynamic behaviors of the fluid supports are considered as nonlinear. The dynamic behavior is analyzed using an unsteady time integration procedure. The paper shows the coupling between the axial dynamic behavior and the bending vibrations of the shaft.

Numerical Investigation of the Flow in a Hydrodynamic Thrust Bearing With Floating Disk

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Magnus Fischer ◽  
Andreas Mueller ◽  
Benjamin Rembold ◽  
Bruno Ammann
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Rotational Velocity ◽  
Control Unit ◽  
Axial Direction ◽  
Lubricating Oil ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Axial Thrust ◽  
Oil Film

In this paper we present a novel method for the numerical simulation of flow in a hydrodynamic thrust bearing with floating disk. Floating disks are commonly employed in turbochargers and are situated between the thrust collar, which is rotating at turbocharger speed, and the static casing. A floating disk reduces wear, improves the skew compensating capacity of the bearing, and is freely movable in the axial direction. The simulation model presented combines a commercial flow solver (ANSYS CFX) with a control unit. Based on physical principles and a predefined axial thrust, the control unit automatically sets the rotational speed of the floating disk, the mass flow of the oil supply, and the oil film thickness between the rotating disk and the casing wall and collar, respectively. The only additional inputs required are the temperature and the pressure of the oil at the oil feed and the turbocharger speed. The width of the computational grid of the thin lubricating oil film in the gaps is adjusted using a mesh-morphing approach. The temperature-dependent variation in viscosity is included in the model. The calculated solution of the flow field in the domain, the oil film thickness, and the resulting rotational velocity of the floating disk are validated against experimental data and demonstrate favorable agreement. The influence of uncertainties in the measurements and the behavior of the systems are thoroughly investigated in parametric studies that reveal the key influencing factors. These are the temperature-dependent viscosity of the oil, the axial thrust, and turbulence effects in the supply grooves and ducts of the floating disk. Using the model presented here, it is now possible to predict design variants for this type of bearing.

The Neural Network Prediction to the Wear and Tear Fault of Thrust Bearing in Air Compressor

2013 ◽  
Vol 333-335 ◽  
pp. 1758-1761
Author(s):  
Song He Zhang ◽  
Yue Gang Luo ◽  
Bin Wu ◽  
Bing Cheng Wang
Keyword(s):  
Neural Network ◽  
Traditional Method ◽  
Thrust Bearing ◽  
Axial Thrust ◽  
Air Compressor ◽  
The Neural Network ◽  
Wear And Tear ◽  
Neural Network Prediction ◽  
Tear Fault ◽  
Artificial Neural Network Ann

The wear and tear allowances (displacements) of axial thrust bearing in air compressor was diagnosed and predicted, applying the model of artificial neural network (ANN), and compared with the traditional method of diagnosis and prediction. It showed that the results of diagnosis and prediction are more precise than that of traditional method. It can diagnosis and predicts the wear and tear allowances of axial thrust bearing better.

scholarly journals Experimental and Simulated Investigation of Lubrication Characteristics of a Water-Lubricated Bearing in a Single-Screw Compressor

2021 ◽  
Vol 11 (21) ◽  
pp. 9920
Author(s):  
Jia Xie ◽  
Chengyu Peng ◽  
Wenshan Zhang ◽  
Cun Zhao ◽  
Quanke Feng
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Water Injection ◽  
Injection Pressure ◽  
Water Film ◽  
Axial Thrust ◽  
Thrust Bearings ◽  
Single Screw ◽  
Model And Simulation ◽  
Lubrication Characteristics

Water-lubricated single-screw compressors (WSSCs) have developed rapidly in recent years because they can supply oil-free compressed air at considerably low costs. However, a major technical obstacle is that the conventional bearing arrangement of a star wheel shaft is prone to wear failure, which makes it difficult for WSSCs to run properly for long periods of time. To solve this problem, a star wheel thrust bearing with new liquid groove was proposed in this paper. Pulsating forces (i.e., bearing forces) acting on a star wheel shaft by compressing air were calculated through the dynamic analysis of the star wheel shaft system. A mathematical model of hydraulic water films in the bearing sliding clearance was established to describe the influence of water injection pressure on water film pressure distribution and its bearing capacity. Lubrication characteristics were compared between two types of hydrostatic thrust bearings (HTBs) with different grooves to illustrate that the new structure is more suitable for WSSCs. The reasonability of the proposed model and simulation results were verified using an axial thrust bearing test rig developed by the authors. In addition, variation parameters of hydrostatic film thickness between the sliding surfaces of the star wheel axial thrust bearing were measured. The results show that the instability of the water film thickness and axial vibration of the star wheel were suppressed, thereby avoiding the contact of solid materials between the end face of the axial thrust bearing. This study provides a structural optimization pattern of star wheel axial thrust bearings used in water-lubricated single-screw compressors.

Analysis of the Segmented Displaced Trapezoidal Winding for Force and Torque Production as a Self Bearing Motor

2005 ◽  
Author(s):  
Lyndon Scott Stephens ◽  
Daniel Impellizzeri
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Large Range ◽  
Thrust Force ◽  
Active Force ◽  
Shaft Length ◽  
Axial Thrust ◽  
Theoretical Predictions ◽  
Radial Forces ◽  
Starter Generator

Self bearing motors have been identified as a potential technology for oil free turbomachinery where integral starter generator (ISG) technology may be used, among others. One of the key advantages of self bearing motors is that they reduce the shaft length of machines, hence increasing the rotordynamic performance. Until now, research has yielded self bearing motors that produce motoring torque and active force control of either the radial forces or the thrust force. In this paper, a new self bearing motor winding is analyzed for its potential to simultaneously produce actively controlled torque, radial forces and thrust force. The benefit of such a design is that the shaft length can be reduced even further as both the radial bearing and thrust bearing functions are performed by the motor. Experimental results are presented that verify the force and torque production capability of the motor to within 14% of the theoretical predictions. Another benefit of the motor is its ability to be used for large axial (thrust) movements, such that it could be used in precision axial positioning of high speed rotating loads over a large range (up to 25 mm or so for a 25 mm diameter rotor).

Numerical Investigation of the Flow in a Hydrodynamic Thrust Bearing With Floating Disk

2012 ◽  
Author(s):  
Magnus Fischer ◽  
Andreas Mueller ◽  
Benjamin Rembold ◽  
Bruno Ammann
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Rotational Velocity ◽  
Control Unit ◽  
Axial Direction ◽  
Lubricating Oil ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Axial Thrust ◽  
Oil Film

In this paper we present a novel method for the numerical simulation of flow in a hydrodynamic thrust bearing with floating disk. Floating disks are commonly employed in turbochargers and are situated between the thrust collar, which is rotating at turbocharger speed, and the static casing. A floating disk reduces wear, improves the skew compensating capacity of the bearing and is freely movable in the axial direction. The simulation model presented combines a commercial flow solver (ANSYS CFX) with a control unit. Based on physical principles and a predefined axial thrust, the control unit automatically sets the rotational speed of the floating disk, the mass flow of the oil supply and the oil film thickness between the rotating disk and the casing wall and collar respectively. The only additional inputs required are the temperature and the pressure of the oil at the oil feed and the turbocharger speed. The width of the computational grid of the thin lubricating oil film in the gaps is adjusted using a mesh-morphing approach. The temperature-dependent variation in viscosity is included in the model. The calculated solution of the flow field in the domain, the oil film thickness and the resulting rotational velocity of the floating disk are validated against experimental data and demonstrate favorable agreement. The influence of uncertainties in the measurements and the behavior of the systems are thoroughly investigated in parametric studies which reveal the key influencing factors. These are the temperature-dependent viscosity of the oil, the axial thrust and turbulence effects in the supply grooves and ducts of the floating disk. Using the model presented here, it is now possible to predict design variants for this type of bearing.

High Temperature Magnetic Thrust Bearing: Theory and Experiment

2019 ◽  
Author(s):  
Mohammad W. Mohiuddin ◽  
Alan B. Palazzolo ◽  
Randy P. Tucker ◽  
Desireddy V. Reddy ◽  
Andrew J. Provenza ◽  
...  
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Circuit Design ◽  
Room Temperature ◽  
Magnetic Force ◽  
Thrust Bearing ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
High Resistivity ◽  
Axial Thrust

Abstract Active magnetic bearings (AMBs) are being increasingly utilized in industrial applications due to their advantages over conventional bearings. They offer very low friction and wear, variable stiffness and damping, and greater tolerance of rotating mass imbalance. These unique features of AMBs have enabled design of robust rotating machinery at much higher speed with higher power concentration. The present work discusses the design of a high temperature magnetic bearing for operation at an axial thrust load of 4448N, speed 20000 rpm and temperature 538°C. Various disk profiles were considered to lower peak stresses due to centrifugal forces, including uniform (rectangular), linear tapered and hyperbolic. The predictions showed that the hyperbolic profile reduced stresses by 60% compared to the rectangular profile enabling rotor disks to operate at much higher speed. A test bearing was built with the hyperbolic disc profile. An Iron-Cobalt alloy, commercially known as Hyperco 27 was utilized for the thrust disc for its high yield strength 570MPa, high saturation flux density of 2.35T and high resistivity of 250μΩ-mm. Hyperco 50A was selected for the bearing stator, due to the lower load requirement and cost. Magnetic circuit design assumptions for the axial thrust AMB included (1) relative permeability of the magnetic material was nearly infinite, (2) fringing at gap edges as well as leakage flux were negligible, and (3) the field within the circuit was homogeneous. The initial circuit design was improved using finite element magnetic field analysis. The effective force acting on the hyperbolic rotor determined the required number of turns and current for the electromagnetic coils. Extensive structural finite element analyses suggested not to use an interference fit of the attached disk with the shaft. Rather, it was decided to utilize a sleeve and lock-nut mechanism. Inconel 718 was used for the shaft due to its slightly higher thermal expansion coefficient than Hyperco 27. The thrust AMB containment vessel included thermally-insulated radial and axial adjustment bolts to position and align the AMB inside the vessel. The AMB rotating assembly was spun using an electric motor. The magnetic force generated by the AMB at room temperature was similar to its predicted value, with a 0.85 derating factor. The magnetic force was temperature dependent and was reduced to 65% of its room temperature value, at 538°C. The maximum operating speed reached thus far in the experimental study was 5000 rpm. The magnetic bearing force was nearly invariant with rotational speed at any given temperature (e.g., room and high), while the electric current was held constant. The design indicates that the novel magnetic thrust bearing should perform well at the target operating conditions of 4448N axial load at 538°C (1000 lb-f at 1000°F), and 20,000 rpm. This has been achieved thus far only up to 5000 rpm. The force appears to be very insensitive to motion induced eddy currents up to the present maximum speed of 5000 rpm. Future work will focus on reaching the full speed target of 20,000 rpm at 538°C and 4,448 N loading.

scholarly journals Rotor Design in Industrial Gas Turbines

1997 ◽  
Author(s):  
Stefan S. Florjancic ◽  
Jörg Pross ◽  
Urban Eschbach
Keyword(s):  
Dynamic Behavior ◽  
Gas Turbines ◽  
Short Circuit ◽  
Turbine Rotor ◽  
Rotational Inertia ◽  
Axial Thrust ◽  
Rotor Design ◽  
Industrial Gas Turbines ◽  
The Individual ◽  
Cooling Air

The various design aspects of an industrial gas turbine rotor need special attention to ensure safe and reliable operation of the entire machine. The rotor has to fulfill the following main criteria and tasks: carry the blading, transmit the torque, define the aerodynamic channel geometry, guide the cooling air, provide sealing and bearing surfaces, and exhibit acceptable rotordynamic behavior. Additional criteria linked to the rotor design can be established, i.e., ease of manufacture and assembly, maintainability (where needed), transient blading tip clearances, rotational inertia, balance of axial thrust, and safety against fault conditions (blade loss, short circuit, hot-gas ingestion, etc.) with possibilities for subsequent repair. Industrial practice shows that there are several design approaches possible. This paper describes the general requirements and how to assess the strength and the dynamic behavior under transient and steady state conditions. Additionally, the individual existing main design principles, i.e., stacked discs with individual centering and tie rod types, and monolithic or welded integral rotor design, are compared. Differences in levels of loading and in the dynamic behavior are outlined. Finally, an assessment of the individual rotor designs under fault conditions is given, and critical areas of the component under such conditions are discussed.

Sign in / Sign up

Export Citation Format

Share Document