Non Linear Dynamic Stability Analysis of Finite Flexible Oil Journal Bearings Including Fluid Inertia Effects

2017 ◽  
Vol 49 (4) ◽  
pp. 195-205
Author(s):  
K.C Ghosh ◽  
◽  
S.K Mazumder ◽  
M.C Majumdar
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Journal Bearings ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Linear Dynamic ◽  
Non Linear

Non-linear stability analysis of micropolar fluid lubricated journal bearings with turbulent effect

2019 ◽  
Vol 71 (1) ◽  
pp. 31-39
Author(s):  
Subrata Das ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Micropolar Fluid ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Content Type ◽  
Non Linear ◽  
The Stability ◽  
Bearing System

Purpose The purpose of this paper is to investigate the effect of turbulence on the stability characteristics of finite hydrodynamic journal bearing lubricated with micropolar fluid. Design/methodology/approach The non-dimensional transient Reynolds equation has been solved to obtain the non-dimensional pressure field which in turn used to obtain the load carrying capacity of the bearing. The second-order equations of motion applicable for journal bearing system have been solved using fourth-order Runge–Kutta method to obtain the stability characteristics. Findings It has been observed that turbulence has adverse effect on stability and the whirl ratio at laminar flow condition has the lowest value. Practical implications The paper provides the stability characteristics of the finite journal bearing lubricated with micropolar fluid operating in turbulent regime which is very common in practical applications. Originality/value Non-linear stability analysis of micropolar fluid lubricated journal bearing operating in turbulent regime has not been reported in literatures so far. This paper is an effort to address the problem of non-linear stability of journal bearings under micropolar lubrication with turbulent effect. The results obtained provide useful information for designing the journal bearing system for high speed applications.

Non-Linear Transient Stability Analysis of a Rigid Rotor Supported on Journal Bearings With Rectangular Dimples

2015 ◽  
Author(s):  
Ram Turaga
Keyword(s):  
Stability Analysis ◽  
Surface Texture ◽  
Transient Stability ◽  
Equations Of Motion ◽  
Journal Bearings ◽  
Pressure Curve ◽  
Rigid Rotor ◽  
Non Linear ◽  
The Stability ◽  
Transient Stability Analysis

The influence of deterministic surface texture on the sub-synchronous whirl stability of a rigid rotor has been studied. Non-linear transient stability analysis has been performed to study the stability of a rigid rotor supported on two symmetric journal bearings with a rectangular dimple of large aspect ratio. The surface texture parameters considered are dimple depth to minimum film thickness ratio and the location of the dimple on the bearing surface. Journal bearings of different Length to diameter ratios have been studied. The governing Reynolds equation for finite journal bearings with incompressible fluid has been solved using the Finite Element Method under isothermal conditions. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. When the dimple is located in the raising part of the pressure curve the positive rectangular dimple is seen to decrease the stability whereas the negative rectangular dimple is seen to improve the stability of the rigid rotor.

Linear Dynamic Stability Analysis of a Surface Piercing Plate Advancing at High Forward Speed

2013 ◽  
Author(s):  
Babak Ommani ◽  
Odd M. Faltinsen
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Domain Boundary ◽  
Vortex Sheet ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Hydrodynamic Coefficients ◽  
Forward Speed ◽  
Linear Distribution ◽  
Linear Dynamic

The dynamic stability of a surface-piercing plate advancing with high forward speed in horizontal plane is investigated in the scope of linear theory. The hydrodynamic forces on the plate in sway and yaw are presented in terms of frequency and forward speed dependent added mass and damping coefficients. Flow separation from the trailing edge of the plate is considered. A time domain boundary integral method using linear distribution of Rankine sources and dipoles on the plate, free surface and a vortex sheet is used to calculate these hydrodynamic coefficients numerically. Comparison between the current numerical results and previous numerical and experimental results are presented. Using linear dynamic stability analysis the influence of hydrodynamic coefficients on the plate’s stability is investigated as a simplified alternative to a semi-displacement vessel.

Stability Boundary of Non-Linear Orbits Within Clearance Circle of Journal Bearings

1993 ◽  
Vol 115 (3) ◽  
pp. 303-307 ◽  
Author(s):  
M. M. Khonsari ◽  
Y. J. Chang
Keyword(s):  
Stability Analysis ◽  
Journal Bearing ◽  
Stability Boundary ◽  
Journal Bearings ◽  
Initial Condition ◽  
Bearing Clearance ◽  
Linearized Stability ◽  
Non Linear

The transient, nonlinear study of journal bearing stability requires tracking the locus of the shaft center as a function of time. It is shown that there exists a boundary within the bearing clearance circle outside of which any initial condition would yield an unstable orbit. This is shown to be the case for operating speeds that are well below the threshold of instability according to the linearized stability analysis.

Linear Dynamic Stability Analysis of a Surface-Piercing Plate Advancing at High Forward Speed

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Babak Ommani ◽  
Odd M. Faltinsen
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Domain Boundary ◽  
Vortex Sheet ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Hydrodynamic Coefficients ◽  
Forward Speed ◽  
Linear Distribution ◽  
Linear Dynamic

The dynamic stability of a surface-piercing plate, advancing with high forward speed in the horizontal plane, is investigated in the scope of linear theory. The hydrodynamic forces on the plate in sway and yaw are presented in terms of frequency and forward speed-dependent added mass and damping coefficients. Flow separation from the trailing edge of the plate is considered. A time-domain boundary integral method using linear distribution of Rankine sources and dipoles on the plate, free surface, and vortex sheet is used to calculate these hydrodynamic coefficients numerically. Comparison between the current numerical results and previous numerical and experimental results is presented. Using linear dynamic stability analysis, the influence of hydrodynamic coefficients on the plate's stability is investigated as a simplified alternative to a semidisplacement vessel.

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