Theoretical considerations of static and dynamic characteristics of air foil thrust bearing with tilt and slip flow

2008 ◽  
Vol 41 (4) ◽  
pp. 282-295 ◽  
Author(s):  
Dong-Jin Park ◽  
Chang-Ho Kim ◽  
Gun-Hee Jang ◽  
Yong-Bok Lee
Keyword(s):  
Dynamic Characteristics ◽  
Thrust Bearing ◽  
Slip Flow ◽  
Static And Dynamic Characteristics ◽  
Foil Thrust Bearing ◽  
Theoretical Considerations

Static and Dynamic Characteristics of Air Foil Thrust Bearing Considering Tilting Pad Condition

2007 ◽  
Author(s):  
Dong-Jin Park ◽  
Yong-Bok Lee ◽  
Chang-Ho Kim ◽  
Gun-Hee Jang
Keyword(s):  
Dynamic Characteristics ◽  
Carrying Capacity ◽  
Gas Turbines ◽  
Thrust Bearing ◽  
Load Carrying Capacity ◽  
Static And Dynamic Characteristics ◽  
Load Carrying ◽  
Foil Thrust Bearing ◽  
Thrust Pad ◽  
Stiffness And Damping

The thrust pad of the rotor is used to sustain the axial force generated due to the pressure difference between the compressor and turbine sides of turbomachinery such as the gas turbines and turbochargers. Furthermore, this thrust pad has a role to maintain and determines the attitude of the rotor. In a real system, it also helps reinforce the stiffness and damping of the journal bearing. This study was performed for the purpose of analyzing the characteristics of the air foil thrust bearing. The model for the air foil thrust bearing used in this study is composed of two parts: one is an inclined plane, which plays a role to increase the load carrying capacity using the physical wedge effect, and the other is a flat plane. This study mainly consists of three parts. First, the static characteristics were obtained over the region of the thin air film using the finite difference method (FDM) and the bump foil characteristics using the finite element method (FEM). Second, the analysis of the dynamic characteristics was conducted by perturbation method. For more exact calculation, the rarefaction gas coefficients perturbed about the pressure and film thickness were taken into consideration. At last, the static and dynamic characteristics of the tilting condition of the thrust pad were obtained. Furthermore, the load carrying capacity and torque were calculated for both tilting and not-tilting conditions. From this study, several results were presented: 1) the stiffness and damping of the bump foil under the condition of the various bump parameters, 2) the load carrying capacity and bearing torque at the tilting state, 3) the bearing performance under various bearing parameters, 4) the effects considering the rarefaction gas coefficients.

Static and Dynamic Characteristics of Aerostatic Circular Porous Thrust Bearings (Effect of the Shape of the Air Supply Area)

2000 ◽  
Vol 123 (3) ◽  
pp. 501-508 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kohno
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Thrust Bearing ◽  
Aerostatic Bearing ◽  
Bearing Surface ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Porous Bearing ◽  
Air Supply ◽  
Bearing Design

Recently, graphite porous material has been used successfully in an aerostatic bearing. In actual bearing design, it is often necessary to reduce the thickness of porous material to make the bearing smaller. However, a reduction in thickness results in a reduction in the strength of the porous material. In particular, when the diameter of porous material is large, it is difficult to supply the air through the full pad area of porous material because it deforms. Therefore, in this paper, two types of air supply method (the annular groove supply and the hole supply) in a circular aerostatic porous thrust bearing are proposed to avoid the deflection of the bearing surface. The static and dynamic characteristics of aerostatic porous bearing with these air supply methods are investigated theoretically and experimentally. In addition, the effects of a surface restricted layer on the characteristics are clarified.

Experimental Analysis of the Dynamic Characteristics of a Foil Thrust Bearing

2014 ◽  
Author(s):  
Franck Balducchi ◽  
Mihai Arghir ◽  
Romain Gauthier
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Dynamic Models ◽  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Test Rig ◽  
Equivalent Damping ◽  
Start Up ◽  
Foil Thrust Bearing

The paper deals with the experimental analysis of the dynamic characteristics of a foil thrust bearing (FTB) designed following the specifications given by NASA in 2009. The start-up characteristics of the same foil bearing were investigated in a recently published paper. The test rig used for start-up measurements was adapted for dynamic measurements. The paper presents the test rig in detail as well as its identified dynamic models. Measurements of the dynamic characteristics of the bump foil structure were performed for static loads comprised between 30 N and 150 N while measurements for the FTB were performed at 35 krpm for 30 N, 60 N and 90 N. Excitation frequencies were comprised between 150 Hz and 750 Hz. Results showed that the dynamic stiffness of the FTB increase with excitation frequency while the equivalent damping decreases. Both stiffness and damping increase with the static load but are smaller at 35 krpm compared to 0 rpm.

Experimental Analysis of the Dynamic Characteristics of a Foil Thrust Bearing

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Franck Balducchi ◽  
Mihai Arghir ◽  
Romain Gauthier
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Gas Turbines ◽  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Equivalent Damping ◽  
Start Up ◽  
And Performance ◽  
Foil Thrust Bearing

This paper deals with the experimental analysis of the dynamic characteristics of a foil thrust bearing (FTB) designed according to specifications given by NASA scientists in 2009 (Dykas et al., 2009, “Design, Fabrication, and Performance of Foil Gas Thrust Bearings for Microturbomachinery Applications,” ASME J. Eng. Gas Turbines Power, 131(1), p. 012301). The present work details the new configuration of the same test rig that was used to test start-up characteristics of the aforementioned bearing (Balducchi et al., 2013, “Experimental Analysis of the Start-Up Torque of a Mildly Loaded Foil Thrust Bearing,” ASME J. Tribol., 135(3), p. 031703). The rig has been reconfigured to test dynamic characteristics. The dynamic characteristics of the bump foil structure were measured for static loads comprised between 30 N and 150 N while measurements for the FTB were performed at 35 krpm for 30 N, 60 N, and 90 N. Excitation frequencies were comprised between 150 Hz and 750 Hz. Results showed that the dynamic stiffness of the FTB increase with excitation frequency while the equivalent damping decreases. Both stiffness and damping increase with the static load but are smaller at 35 krpm compared to 0 rpm.

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