Dynamic Behavior of a Journal Bearing in a Planet Gear

1983 ◽  
Vol 26 (1) ◽  
pp. 87-93 ◽  
Author(s):  
J. L. Nikolajsen ◽  
M. Botman
Keyword(s):  
Dynamic Behavior ◽  
Journal Bearing ◽  
Planet Gear

Dynamic Behavior of Pure Squeeze Films in Narrow Porous Bearings

1974 ◽  
Vol 96 (3) ◽  
pp. 361-364 ◽  
Author(s):  
P. R. K. Murti
Keyword(s):  
Dynamic Behavior ◽  
Cyclic Load ◽  
Journal Bearing ◽  
Load Capacity ◽  
Squeeze Film ◽  
Closed Form Expression ◽  
Cyclic Loads ◽  
Eccentricity Ratio ◽  
Form Expression ◽  
Bearing Material

The dynamic behavior of squeeze film in a narrow porous journal bearing under a cyclic load is analyzed. A thin-walled bearing with a nonrotating journal is considered and a closed form expression for the pressure distribution is derived. The locus of the journal center is found by numerical methods and it is established with an example that actual contact between the journal and bearing can be avoided by appropriate design of the bearing. Consequently, it is proved that pure squeeze films have a load capacity only under cyclic loads. The analysis also reveals that the permeability of the bearing material and the wall thickness of the bearing influence significantly the operating eccentricity ratio.

Effect of the Wave Amplitude on the Dynamic Behavior of a Wave Journal Bearing

2008 ◽  
Author(s):  
Nicoleta M. Ene ◽  
Florin Dimofte ◽  
Fred B. Oswald
Keyword(s):  
Dynamic Behavior ◽  
Wave Amplitude ◽  
Journal Bearing ◽  
Experimental Results ◽  
Transient Method ◽  
Poincaré Maps ◽  
Poincare Maps ◽  
Bearing Clearance ◽  
Bearing Behavior ◽  
Good Agreement

The effect of the wave amplitude on the dynamic behavior of a three-wave journal bearing is analyzed. A transient method was used to predict the wave bearing behavior after Fractional Whirl Frequency (FFW) occurs. Dynamic trajectories, Poincare´ maps, and FFT analyses are used to study the dynamic behavior of the journal bearing. It was found that the threshold of stability is strongly influenced by the wave amplitude. However, even when FFW occurs, the journal maintains its trajectory inside the bearing clearance. The predicted data were found to be in good agreement with the experimental results obtained at the NASA GRC.

Three-Dimensional Dynamic Model of TEHD Tilting-Pad Journal Bearing—Part I: Theoretical Modeling

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Junho Suh ◽  
Alan Palazzolo
Keyword(s):  
Heat Conduction ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Journal Bearing ◽  
Three Dimensional ◽  
Physical Parameters ◽  
Tilting Pad ◽  
Fluid Film Thickness ◽  
Three Dimensional Finite Element ◽  
Tilting Pad Journal Bearing

This paper is focused on a new modeling method of three-dimensional (3D) thermo-elasto-hydro-dynamic (TEHD) cylindrical pivot tilting-pad journal bearing (TPJB). Varying viscosity Reynolds equation and 3D energy equation are coupled via lubricant temperature and viscosity relationship. Three-dimensional finite element method (FEM) is adopted for the analysis of: (1) heat conduction in shaft and bearing pad, (2) thermal deformation of shaft and pad, (3) flexible bearing pad dynamic behavior, and (4) heat conduction, convection, and viscous shearing in thin lubricant film. For the computational efficiency, modal coordinate transformation is utilized in the flexible pad dynamic model, and pad dynamic behavior is represented only by means of modal coordinate. Fluid film thickness is calculated by a newly developed node based method, where pad arbitrary thermal and elastic deformation and journal thermal expansion are taken into account simultaneously. The main goal of this research is to provide more accurate numerical TPJB model than developed before so that the designers of rotating machinery are able to understand the bearing dynamic behavior and avoid unpredicted problem by selection of physical parameters.

Stability Analysis of an Industrial Gas Compressor Supported by Tilting-Pad Bearings Under Different Lubrication Regimes

2011 ◽  
Author(s):  
Alejandro Cerda Varela ◽  
Ilmar Ferreira Santos
Keyword(s):  
Stability Analysis ◽  
Dynamic Behavior ◽  
Journal Bearing ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Stable Operating ◽  
Tilting Pad ◽  
The Stability ◽  
Tilting Pad Journal Bearing ◽  
Bearing System

This work is aimed at theoretically study the dynamic behavior of a rotor-tilting pad journal bearing system under different lubrication regimes, namely thermohydrodynamic (THD), elastohydrodynamic (EHD) and hybrid lubrication regime. The rotor modeled corresponds to an industrial compressor. Special emphasis is put on analyzing the stability map of the rotor when the different lubrication regimes are included into the TPJB modeling. Results show that, for the studied rotor, the inclusion of a THD model is more relevant when compared to an EHD model, as it implies a reduction on the instability onset speed for the rotor. Also, results show the feasibility of extending the stable operating range of the rotor by implementing a hybrid lubrication regime.

Cyclic Squeeze Films in Micropolar Fluid Lubricated Journal Bearings

1976 ◽  
Vol 98 (3) ◽  
pp. 412-417 ◽  
Author(s):  
J. Prakash ◽  
P. Sinha
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Loading ◽  
Micropolar Fluid ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Detailed Consideration ◽  
Sinusoidal Load ◽  
Fluid Theory ◽  
Curve Form

The Reynolds equation for the general case of dynamic loading is derived for fluid suspensions, using the micropolar fluid theory. Detailed consideration is given to the dynamic behavior of squeeze films in journal bearings under a fluctuating load with no journal rotation. The characteristics of an infinitely long journal bearing under a cyclic sinusoidal load are shown in curve form, so as to elaborate the micropolar effects.

Effects of Bearing Stiffness Anisotropy on Hydrostatic Micro Gas Journal Bearing Dynamic Behavior

2005 ◽  
Author(s):  
L. X. Liu ◽  
Z. S. Spakovszky
Keyword(s):  
Numerical Simulations ◽  
Dynamic Behavior ◽  
High Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Stiffness Anisotropy ◽  
Bearing Stiffness ◽  
Gas Bearing ◽  
Gas Journal Bearing ◽  
Fabrication Tolerance

The high-speed micro hydrostatic gas journal bearings used in the high-power density MIT micro-engines are of very low aspect ratio with an L/D of less than 0.1 and are running at surface speeds of order 500 m/s. These ultra-short high-speed bearings exhibit whirl instability limits and a dynamic behavior much different from conventional hydrostatic gas bearings. The design space for stable high-speed operation is confined to a narrow region and involves singular behavior (Spakovszky and Liu (2003)). This together with the limits on achievable fabrication tolerance that can be achieved in the silicon chip manufacturing technology severely affects bearing operability and limits the maximum achievable speeds of the micro turbomachinery. This paper introduces a novel variation of the axial-flow hydrostatic micro-gas journal bearing concept which yields anisotropy in bearing stiffness. By departing from axial symmetry and introducing biaxial symmetry in hydrostatic stiffness, the bearing’s top speed is increased and fabrication tolerance requirements are substantially relieved making more feasible extended stable high-speed bearing operation. The objectives of this work are: (1) to characterize the underlying physical mechanisms and the dynamic behavior of this novel bearing concept, and (2) to report on the design, implementation and test of this new micro-bearing technology. The technical approach involves the combination of numerical simulations, experiment, and simple, first principles based modeling of the gas bearing flow field and the rotordynamics. A simple description of the whirl instability threshold with stiffness anisotropy is derived explaining the instability mechanisms and linking the governing parameters to the whirl ratio and stability limit. An existing analytical hydrostatic gas bearing model is extended and modified to guide the bearing design with stiffness anisotropy. Numerical simulations of the full non-linear governing equations are conducted to validate the theory and the novel bearing concept. Experimental results obtained from a micro-bearing test device are presented and show good agreement between the theory and the measurements. The theoretical increase in achievable bearing top speed and the relief in fabrication tolerance requirements due to stiffness anisotropy are quantified and important design implications and guidelines for micro gas journal bearings are discussed.

Stability Analysis of an Industrial Gas Compressor Supported by Tilting-Pad Bearings Under Different Lubrication Regimes

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Alejandro Cerda Varela ◽  
Ilmar Ferreira Santos
Keyword(s):  
Stability Analysis ◽  
Dynamic Behavior ◽  
Theoretical Study ◽  
Journal Bearing ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Stable Operating ◽  
Tilting Pad ◽  
The Stability ◽  
Tilting Pad Journal Bearing

This work is aimed at a theoretical study of the dynamic behavior of a rotor-tilting pad journal bearing (TPJB) system under different lubrication regimes, namely, thermohydrodynamic (THD), elastohydrodynamic (EHD), and hybrid lubrication regime. The rotor modeled corresponds to an industrial compressor. Special emphasis is put on analyzing the stability map of the rotor when the different lubrication regimes are included into the TPJB modeling. Results show that, for the studied rotor, the inclusion of a THD model is more relevant when compared to an EHD model, as it implies a reduction on the instability onset speed for the rotor. Also, results show the feasibility of extending the stable operating range of the rotor by implementing a hybrid lubrication regime.

On the Dynamic Behavior of Two Gas-Lubricated Two-Lobe Journal Bearing Configurations

1983 ◽  
Vol 26 (3) ◽  
pp. 411-414 ◽  
Author(s):  
M. Chandra ◽  
M. Malik ◽  
R. Sinhasan
Keyword(s):  
Dynamic Behavior ◽  
Journal Bearing
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