scholarly journals Dynamic analysis of short and long journal bearings in laminar and turbulent regimes, application in critical shaft stiffness determination

2017 ◽  
Vol 48 ◽  
pp. 451-475 ◽  
Author(s):  
Farzad Hemmati ◽  
Mohammad Miraskari ◽  
Mohamed S. Gadala
Keyword(s):  
Dynamic Analysis ◽  
Journal Bearings ◽  
Laminar And Turbulent Regimes

scholarly journals Mobility Method Applied to Calculate the Lubrication Properties of Bearing under Dynamic Loads

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Tao He ◽  
Xiqun Lu ◽  
Jingzhi Zhu
Keyword(s):  
Dynamic Analysis ◽  
Mechanical Systems ◽  
Journal Bearings ◽  
Numerical Results ◽  
Dynamic Loads ◽  
Analysis Program ◽  
Computational Program ◽  
Dynamically Loaded ◽  
Mobility Method ◽  
Lubrication Properties

The analytical mobility method for dynamically loaded journal bearings was presented, with the intent to include it in a general computational program, such as the dynamic analysis program, that has been developed for the dynamic analysis of general mechanical systems. An illustrative example and numerical results were presented, with the efficiency of the method being discussed in the process of their presentation.

Linear stability analysis of finite length journal bearings in laminar and turbulent regimes

2017 ◽  
Vol 231 (10) ◽  
pp. 1254-1267 ◽  
Author(s):  
Mohammad Miraskari ◽  
Farzad Hemmati ◽  
MY Alqaradawi ◽  
Mohamed S Gadala
Keyword(s):  
Linear Stability ◽  
Finite Length ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Stable Region ◽  
Dynamic Coefficients ◽  
Rotor Bearing ◽  
High Reynolds ◽  
Turbulent Models ◽  
Laminar And Turbulent Regimes

Dynamic coefficients of a finite length journal bearing are numerically calculated under laminar and turbulent regimes based on Ng–Pan–Elrod and Constantinescu models. Linear stability charts of a flexible rotor supported on laminar and turbulent journal bearings are found by calculating the threshold speed of instability associated to the start of instable oil whirl phenomenon. Local journal trajectories of the rotor-bearing system were found at different operating conditions solely based on the calculated dynamic coefficients in laminar and turbulent flow. Results show no difference between laminar and turbulent models at low loading while significant change of the size of the stable region was observed by increasing the Reynolds number in turbulent models. Stable margins based on the laminar flow at relatively low Sommerfeld numbers [Formula: see text] were shown to fall inside the unstable region and hence rendering the laminar stability curves obsolete at high Reynolds numbers. Ng-Pan turbulent model was found to be generally more conservative and hence is recommended for rotor-bearing design.

Nonlinear Dynamic Analysis of a Flexible Rotor Supported by Externally Pressurized Porous Gas Journal Bearings

2002 ◽  
Vol 124 (3) ◽  
pp. 553-561 ◽  
Author(s):  
Cheng-Chi Wang ◽  
Cheng-Ying Lo ◽  
Cha’o-Kuang Chen
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Power Spectra ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Flexible Rotor ◽  
Bearing Number ◽  
Rotor Mass

This paper studies the nonlinear dynamic analysis of a flexible rotor supported by externally pressurized porous gas journal bearings. A time-dependent mathematical model for externally pressurized porous gas journal bearings is presented. The finite difference method and the Successive Over Relation (S.O.R.) method are employed to solve the modified Reynolds’ equation. The system state trajectory, Poincare´ maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and quasi-periodic response of the rotor and journal center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and bearing number. The results of this study contribute to a further understanding of the nonlinear dynamics of gas-lubricated, externally pressurized, porous rotor-bearing systems.

A comparison of methods of modelling the bearing surfaces in an internal combustion engine

2011 ◽  
Vol 226 (4) ◽  
pp. 913-920 ◽  
Author(s):  
P D McFadden ◽  
S R Turnbull
Keyword(s):  
Internal Combustion Engine ◽  
Dynamic Analysis ◽  
Journal Bearing ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Journal Bearings ◽  
Comparison Of Methods ◽  
Piston Motion ◽  
Piston Cylinder

An existing model for the dynamic analysis of the piston motion in an internal combustion engine has been modified to incorporate a simpler representation of the piston–cylinder interaction, and to represent the main and big-end bearings as lubricated rather than dry journal bearings. The results demonstrate that the differences in calculated bearing forces and output torques are negligible, indicating that the simple dry journal bearing model is sufficient, but show that the modelling of the interaction between piston and cylinder is considerably improved.

Sign in / Sign up

Export Citation Format

Share Document