A Study of Thermohydrodynamic Features of Multi Wound Foil Bearing Using Lobatto Point Quadrature

2008 ◽  
Author(s):  
Kai Feng ◽  
Shigehiko Kaneko
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Iteration Process ◽  
Element Model ◽  
Air Bearings ◽  
Foil Bearing ◽  
Deformation Equation ◽  
Wide Range

The applications of foil air bearings, which are recognized to be the best choice for oil free applications, have been extended for use in a wide range of turbo-miachineries with high speed and high temperature. Lubricant temperature becomes an important factor in the performance of foil air bearings, especially at high rotational speeds and high loads or at high ambient temperature. However, most of the published foil air bearing models were based on the isothermal assumption. This study presents a thermohydrodynamic analysis (THD) of Multi Wound Foil Bearing (MWFB), in which the Reynolds’ equation is solved with the gas viscosity as a function of temperature that is obtained from the energy equation. Lobatto point quadrature, which was proposed by Elrod and Brewe and introduced into compressible calculation by Moraru and Keith, is utilized to accelerate the iteration process with a sparse mesh across film thickness. A finite element model of the foil is used to describe the foil elasticity. An iterative procedure is performed between the Reynolds’ equation, the foil elastic deformation equation and the energy equation, until the convergence is achieved. A three-dimensional temperature prediction of air film is presented and a comparison of THD to isothermal results is made to emphasize the importance of thermal effects. Finally, published experimental data are used to validate this numerical solution.

Thermohydrodynamic Study of Multiwound Foil Bearing Using Lobatto Point Quadrature

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Kai Feng ◽  
Shigehiko Kaneko
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Iteration Process ◽  
Element Model ◽  
Air Bearings ◽  
Foil Bearing ◽  
Wide Range ◽  
Air Film

The applications of foil air bearings have been extended for use in a wide range of turbomachineries with high speed and high temperature. Lubricant temperature becomes an important factor in the performance of foil air bearings, especially at high rotational speeds and high loads or at high ambient temperature. This study presents a thermohydrodynamic (THD) analysis of multiwound foil bearing, in which the Reynolds’ equation is solved with gas viscosity as a function of temperature that is obtained from the energy equation. Lobatto point quadrature is utilized to accelerate the iteration process with a sparse mesh across film thickness. A finite element model of the foil is used to describe the foil elasticity. An iterative procedure is performed between the Reynolds equation, the foil elastic deflection equation, and the energy equation until convergence is achieved. A three-dimensional temperature prediction of air film is presented, and a comparison of THD to isothermal results is made to emphasize the importance of thermal effects. Finally, published experimental data are used to validate this numerical solution.

Thermo-elastohydrodynamic analysis of the inhomogeneous foil bearing with misalignment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hao Li ◽  
Haipeng Geng ◽  
Hao Lin
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Dynamic Performance ◽  
Gas Temperature ◽  
Content Type ◽  
Rotor Systems ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Deformation Equation ◽  
Small Perturbation Method

Purpose The misalignment is generally inevitable in the process of machining and assembly of rotor systems with gas foil bearings, but the exploration on this phenomenon is relatively less. Therefore, the purpose of this paper is to carry out the thermo-elastohydrodynamic analysis of the foil bearing with misalignment, especially the inhomogeneous foil bearing. Design/methodology/approach The rotor is allowed to misalign in two non-rotating directions. Then the static and dynamic performance of the inhomogeneous foil bearing is studied. The thermal-elastohydrodynamic analysis is realized by combining the Reynolds equation, foil deformation equation and energy equation. The small perturbation method is used to calculate the dynamic coefficients, then the critical whirl ratio is obtained. Findings The gas pressure, film thickness and temperature distribution distort when the misalignment appears. The rotor misalignment can improve the loading capacity but rise the gas temperature at the same time. Furthermore, the rotor misalignment can affect the critical whirl ratio which demonstrates that it is necessary to analyze the misalignment before the rotordynamic design. Originality/value The value of this paper is the exploration of the thermo-elastohydrodynamic performance of the inhomogeneous foil bearing with misalignment, the analysis procedure and the corresponding results are valuable for the design of turbo system with gas foil bearings.

Theoretical Performance of a Hydrostatic Foil Bearing

1994 ◽  
Vol 116 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Marc Carpino ◽  
Jih-Ping Peng
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Structural Model ◽  
Three Dimensional ◽  
Element Model ◽  
Element Formulation ◽  
Foil Bearing ◽  
Dimensional Finite Element ◽  
Membrane Effects ◽  
Three Dimensional Finite Element

The performance of a hydrostatic foil journal bearing operating with an incompressible fluid is discussed. In the configuration considered here, pressurized lubricant fluid is supplied through capillaries to recessed pockets on the surface of the journal. The foil is treated as a perfectly flexible, inextensible shell by a three dimensional finite element model. The pressure distribution is predicted by a finite element formulation of the incompressible Reynolds equation. Results are presented which demonstrate that the foil structure enhances load support while increasing lubricant film thickness. In addition, results indicate that membrane effects are essential in the structural model.

scholarly journals Run-Up Simulation of a Semi-Floating Ring Supported Turbocharger Rotor Considering Thrust Bearing and Mass-Conserving Cavitation

Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 44
Author(s):  
Christian Ziese ◽  
Cornelius Irmscher ◽  
Steffen Nitzschke ◽  
Christian Daniel ◽  
Elmar Woschke
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Three Dimensional ◽  
Reliable Prediction ◽  
Two Phase ◽  
Hydrodynamic Bearings ◽  
Thrust Bearings ◽  
Run Up ◽  
The Impact

The vibration behaviour of turbocharger rotors is influenced by the acting loads as well as by the type and arrangement of the hydrodynamic bearings and their operating condition. Due to the highly non-linear bearing behaviour, lubricant film-induced excitations can occur, which lead to sub-synchronous rotor vibrations. A significant impact on the oscillation behaviour is attributed to the pressure distribution in the hydrodynamic bearings, which is influenced by the thermo-hydrodynamic conditions and the occurrence of outgassing processes. This contribution investigates the vibration behaviour of a floating ring supported turbocharger rotor. For detailed modelling of the bearings, the Reynolds equation with mass-conserving cavitation, the three-dimensional energy equation and the heat conduction equation are solved. To examine the impact of outgassing processes and thrust bearing on the occurrence of sub-synchronous rotor vibrations separately, a variation of the bearing model is made. This includes run-up simulations considering or neglecting thrust bearings and two-phase flow in the lubrication gap. It is shown that, for a reliable prediction of sub-synchronous vibrations, both the modelling of outgassing processes in hydrodynamic bearings and the consideration of thrust bearing are necessary.

Study of arching behaviour and strength of concrete masonry infills under out-of-plane loading

2019 ◽  
Vol 46 (10) ◽  
pp. 896-908 ◽  
Author(s):  
Ehsan Nasiri ◽  
Yi Liu
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Contributing Factors ◽  
Concrete Frames ◽  
Masonry Infills ◽  
Concrete Masonry ◽  
Wide Range ◽  
Out Of Plane ◽  
Three Dimensional Finite Element

A numerical study using a three-dimensional finite element model was conducted to investigate the arching behaviour and strength of concrete masonry infills bounded by reinforced concrete frames subjected to out-of-plane loading. Physical specimens were concurrently tested to provide results for validation of the model as well as evidence of directional characteristics of arching behaviour of masonry infills. A subsequent parametric study using the model included a wide range of infilled frame geometric properties. The results showed in detail the difference in one-way and two-way arching in terms of both strength and failure mechanism, and the contributing factors to this difference. Evaluation of the two main design equations for out-of-plane strength of masonry infills led to proposal of modifications to provide a more rational consideration of directional behaviour of concrete masonry infills. A comparison study using the available test results showed a marked improvement of strength prediction based on the proposed modification.

Influence of Geometric Features of the Peripheral Part of the Thin-Walled Spherical Segment on the Explosive Throwing Process

2020 ◽  
pp. 76-87
Author(s):  
M.A. Baburin ◽  
V.D. Baskakov ◽  
S.V. Eliseev ◽  
K.A. Karnaukhov ◽  
V.A. Tarasov
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Rotation ◽  
Aerodynamic Coefficients ◽  
Peripheral Part ◽  
High Speed Impact ◽  
Wide Range ◽  
Main Factors ◽  
Thin Walled ◽  
Axisymmetric Shape

The main factors controlling the formation of the stern of explosively formed projectiles are investigated using numerical calculations in a three-dimensional formulation of a problem. To form folds in the stern, it is proposed to use thin-walled spherical segments with a peripheral thickness deviation in terms of decreasing or increasing with respect to the thickness in the central part. The configurations of explosively formed projectiles with inclined folds in the stern are shown, and it is proposed to describe the fold inclination by two angles of its position. The effect of folds in the stern on the change in aerodynamic coefficients for a wide range of angle of attack is numerically studied. The angular velocity of the axial rotation of explosively formed projectiles with inclined folds in the stern is estimated based on the Newton method and considering the angles of its position. The results obtained are of interest to specialists working in the field of physics of explosion and high-speed impact, as well as those dealing with aerodynamics of aircrafts, mainly of axisymmetric shape

Foil Air/Gas Bearing Technology — An Overview

1997 ◽  
Author(s):  
Giri L. Agrawal
Keyword(s):  
High Temperature ◽  
Analytical Methods ◽  
High Speed ◽  
Test Results ◽  
Air Bearings ◽  
Mean Time Between Failure ◽  
Foil Bearing ◽  
Cryogenic Liquids ◽  
Gas Bearing ◽  
Mean Time

This paper summarizes the chronological progress of foil air bearings for turbomachinery during the last 25 years. Descriptions of various machines which are in production are provided. The foil bearing air cycle machine on the 747 aircraft has demonstrated an MTBF (mean time between failure) in excess of 100,000 hours. Many advantages of foil air bearings are noted. Various designs of foil air bearings presently in use and their relative merits are described. Analytical methods, their limitations, and their relationships with test results are noted. Descriptions of various machines built and tested in process fluids being gases, other than air, and cryogenic liquids are described. Conclusions are drawn that various high speed turbomachines including high temperature applications can be designed and developed using foil air bearings which will increase efficiency and reduce cost of these machines.

scholarly journals Vibration Response Characteristics of the Cross Tunnel Structure

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Jinxing Lai ◽  
Kaiyun Wang ◽  
Junling Qiu ◽  
Fangyuan Niu ◽  
Junbao Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Vibration Response ◽  
Shield Tunnel ◽  
Tunnel Structure ◽  
Response Characteristics ◽  
Vehicle Load ◽  
Metro Tunnel

It is well known that the tunnel structure will lose its function under the long-term repeated function of the vibration effect. A prime example is the Xi’an cross tunnel structure (CTS) of Metro Line 2 and the Yongningmen tunnel, where the vibration response of the tunnel vehicle load and metro train load to the structure of shield tunnel was analyzed by applying the three-dimensional (3D) dynamic finite element model. The effect of the train running was simulated by applying the time-history curves of vibration force of the track induced by wheel axles, using the fitted formulas for vehicle and train vibration load. The characteristics and the spreading rules of vibration response of metro tunnel structure were researched from the perspectives of acceleration, velocity, displacement, and stress. It was found that vehicle load only affects the metro tunnel within 14 m from the centre, and the influence decreases gradually from vault to spandrel, haunch, and springing. The high-speed driving effect of the train can be divided into the close period, the rising period, the stable period, the declining period, and the leaving period. The stress at haunch should be carefully considered. The research results presented for this case study provide theoretical support for the safety of vibration response of Metro Line 2 structure.

Thermal Analysis and Optimization Design on Spindle Bearing of GSCK200A CNC Lathe

2011 ◽  
Vol 314-316 ◽  
pp. 1760-1763
Author(s):  
Le Ping Liu ◽  
Guo Hong Deng
Keyword(s):  
High Speed ◽  
Thermal Deformation ◽  
Optimization Design ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Clearance ◽  
Spindle Bearing ◽  
Heat Transfer Theory ◽  
Cnc Lathe ◽  
Three Dimensional Finite Element

Establish the three-dimensional finite element model of GSCK200A type High-speed & high-precision CNC Lathe spindle bearing, based on tribology and heat transfer theory, using ANSYS to analyze the corresponding temperature field and thermal deformation of spindle bearing in steady working state, according to this thermal deformation to obtain decrease volume of radial clearance, and the installation clearance optimization scheme is putted forward.

Static and Dynamic Analysis of Multileaf Foil Journal Bearings Considering Misalignment Effects

1997 ◽  
Author(s):  
D. Sudheer Kumar Reddy ◽  
S. Swarnamani ◽  
B. S. Prabhu
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Performance Characteristics ◽  
Frictional Torque ◽  
Static And Dynamic Analysis ◽  
Foil Bearing ◽  
Deformation Equation ◽  
Load Carrying ◽  
Static Performance ◽  
Stiffness And Damping

Abstract In the present work the analysis of gas lubricated multileaf journal bearing has been presented. The two dimensional compressible Reynolds equation was solved to establish the pressure field in the clearance space of the bearing. Elastic deformation equation is coupled with the Reynolds equation to get the foil deflections and change in film thickness. The effect of bearing misalignment on foil bearing performance characteristics has been presented. The problem has been formulated using incremental finite element method. The effect of bearing misalignment on static performance characteristics like load carrying capacity, frictional torque, minimum film thickness and on dynamic characteristics in terms of stiffness and damping coefficients have been presented.

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