Study of Conical Whirl Instability of Externally Pressurized Porous Oil Journal Bearings With Tangential Velocity Slip

1986 ◽  
Vol 108 (2) ◽  
pp. 256-261 ◽  
Author(s):  
S. K. Guha
Keyword(s):  
Tangential Velocity ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Conical Whirl ◽  
Film Interface

In the present paper, an attempt has been made to study theoretically the conical whirl instability of unloaded hydrostatic porous oil journal bearings with tangential velocity slip on the bearing film interface. The effect of various parameters on stability has also been investigated.

Study of Conical Whirl Instability of Self-Acting Porous Gas Journal Bearings Considering Tangential Velocity Slip

1988 ◽  
Vol 110 (1) ◽  
pp. 139-143
Author(s):  
S. K. Guha ◽  
N. S. Rao ◽  
B. C. Majumdar
Keyword(s):  
Tangential Velocity ◽  
Hydrodynamic Pressure ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Stability Characteristic ◽  
Damping Coefficients ◽  
Conical Whirl ◽  
Angular Displacements ◽  
Stiffness And Damping ◽  
Film Interface

The purpose of the present work is to study theoretically the conical whirl instability of unloaded self-acting porous gas journal bearings considering the tangential velocity slip at the bearing-film interface. The hydrodynamic pressure developed in the bearing clearance due to angular displacements of the journal at the midplane of the bearing is obtained by the simultaneous solution of equation of continuity in the porous medium and the modified Reynolds equations, satisfying the appropriate boundary conditions. With the help of the dynamic tilting stiffness and damping coefficients, stability characteristic is obtained. The effects of various parameters on conical stability parameter have been investigated for a nongyroscopic system.

Dynamic Characteristics of Finite Porous Journal Bearings Considering Tangential Velocity Slip

1984 ◽  
Vol 106 (4) ◽  
pp. 534-536 ◽  
Author(s):  
A. K. Chattopadhyay ◽  
B. C. Majumdar
Keyword(s):  
Theoretical Investigation ◽  
Finite Length ◽  
Dynamic Characteristics ◽  
Tangential Velocity ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Film Interface

A theoretical investigation to find out the dynamic characteristics of porous journal bearings of finite length has been carried out considering the Beavers-Joseph crierion of velocity slip at the bearing film interface. It has been shown that the effect of velocity slip on the dynamic characteristics is small.

Stability of a Rigid Rotor in Finite Externally Pressurized Oil Journal Bearings With Slip

1987 ◽  
Vol 109 (2) ◽  
pp. 301-306 ◽  
Author(s):  
Ajit Kumar Chattopadhyay ◽  
B. C. Majumdar ◽  
N. S. Rao
Keyword(s):  
Theoretical Analysis ◽  
Finite Length ◽  
Tangential Velocity ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
The Stability ◽  
Film Interface

A theoretical analysis has been carried out to determine the stability characteristics of externally pressurized porous oil journal bearings of finite length considering the tangential velocity slip at the bearing-film interface. The stability curves have been drawn for different slip parameters, eccentricity ratios, slenderness ratios, bearing speed parameters etc.

On the linear stability analysis of finite-hydrodynamic porous journal bearings under coupled stress lubrication

2007 ◽  
Vol 221 (7) ◽  
pp. 831-840 ◽  
Author(s):  
S. K. Guha ◽  
A. K. Chattopadhyay
Keyword(s):  
Reynolds Equation ◽  
Dynamic Performance ◽  
Slip Flow ◽  
Tangential Velocity ◽  
Continuum Theory ◽  
Transient State ◽  
Velocity Slip ◽  
Journal Bearings ◽  
The Stability ◽  
Coupled Stress

The objective of the present investigation is to study theoretically, using the finite-difference techniques, the dynamic performance characteristics of finite-hydrodynamic porous journal bearings lubricated with coupled stress fluids. In the analysis based on the Stokes micro-continuum theory of the rheological effects of coupled stress fluids, a modified form of Reynolds equation governing the transient-state hydrodynamic film pressures in porous journal bearings with the effect of slip flow of coupled stress fluid as lubricant is obtained. Moreover, the tangential velocity slip at the surface of porous bush has been considered by using Beavers-Joseph criterion. Using the first-order perturbation of the modified Reynolds equation, the stability characteristics in terms of threshold stability parameter and whirl ratios are obtained for various parameters viz. permeability factor, slip coefficient, bearing feeding parameter, and eccentricity ratio. The results show that the coupled stress fluid exhibits better stability in comparison with Newtonian fluid.

Unraveling Paradoxical Theories for Rigid Body Collisions

1991 ◽  
Vol 58 (4) ◽  
pp. 1049-1055 ◽  
Author(s):  
W. J. Stronge
Keyword(s):  
Frictional Force ◽  
Contact Point ◽  
Tangential Velocity ◽  
Velocity Slip ◽  
Rigid Bodies ◽  
Contact Points ◽  
Before And After ◽  
Limited Applicability ◽  
Work Done ◽  
Impulsive Reaction

A collision between two rigid bodies has a normal impulsive reaction at the contact point (CP). If the bodies are slightly rough and the contact points have a relative tangential velocity (slip), there is also a frictional force that opposes slip. Small initial slip can halt before contact terminates; when slip halts the frictional force changes and the collision process is separated into periods before and after halting. An energetically consistent theory for collisions with slip that halts is based on the work done by normal (nonfrictional) forces during restitution and compression phases. This theory clearly separates dissipation due to frictional forces from that due to internal irreversible deformation. With this theory, both normal and tangential components of the impulsive reaction always dissipate energy during collisions. In contrast, Newton’s impact law results in calculations of paradoxical increases in energy for collisions where slip reverses. This law relates normal components of relative velocity for the CP at separation and incidence by a constant (the coefficient of restitution e). Newton’s impact law is a kinematic definition for e that generally depends on the slip process and friction; consequently it has limited applicability.

Effect of velocity slip in a narrow rough porous journal bearing

2003 ◽  
Vol 217 (1) ◽  
pp. 59-70 ◽  
Author(s):  
K Gururajan ◽  
J Prakash
Keyword(s):  
Porous Material ◽  
Coefficient Of Friction ◽  
Strong Interaction ◽  
Journal Bearing ◽  
Load Capacity ◽  
Tangential Velocity ◽  
Velocity Slip ◽  
Qualitative And Quantitative ◽  
Slip Effects ◽  
Thin Walled

The paper examines the effect of velocity slip in a thin-walled infinitely short rough porous journal bearing operating under steady conditions in a hydrodynamic regime. The analysis extends earlier work [1] in which the tangential velocity at the surface of the porous material was neglected. The problem is solved analytically together with associated boundary conditions. It is found that there exists a strong interaction between roughness and slip effects. A comparison with the case of an infinitely long journal bearing [2] shows that there are significant qualitative and quantitative differences in load capacity and coefficient of friction. However, the slip-induced variations in friction force are similar to those for an infinitely long journal bearing.

Linear stability analysis of double-layered porous journal bearings under coupled-stress lubrication with slip flow and percolation effect of additives

2019 ◽  
Vol 71 (3) ◽  
pp. 447-458 ◽  
Author(s):  
Shitendu Some ◽  
Sisir Kumar Guha
Keyword(s):  
Linear Stability ◽  
Mass Parameter ◽  
Critical Mass ◽  
Slip Flow ◽  
Tangential Velocity ◽  
Journal Bearings ◽  
Content Type ◽  
Percolation Effect ◽  
The Stability ◽  
Coupled Stress

Purpose In the application of hydrostatic double-layered porous journal bearings, instability of bearing systems is a major problem. On the other hand, the use of non-Newtonian fluid as a lubricant is more practical in the present days. Furthermore, in case of porous bearing, neglecting slip effect and percolation effect of additives into the pores may lead to erroneous result. Hence, this paper aims to present the linear stability analysis of finite hydrostatic double-layered porous journal bearings lubricated with coupled-stress lubricant with tangential velocity slip and percolation effect. Design/methodology/approach First, considering the tangential velocity slip, the most general modified Reynolds-type equation has been derived for the film region and the governing equations for flow in the coarse and fine layers of porous medium incorporating the percolation effect. A linearized first-order perturbation method has been applied to obtain the threshold of stability in terms of critical mass parameter. The effect of various parameters on the stability is investigated and represented in the form of graphs. Furthermore, a comparison between the stability of double- and single-layered porous journal bearings has been exhibited. Findings In this paper, threshold of stability has been obtained in terms of critical mass parameter. The effect of slip coefficient, percolation factor, coupled-stress parameter, eccentricity ratio and bearing feeding parameter on the stability has been found. Originality/value There is no literature available so far that addresses the analysis of the linear stability of externally pressurized double-layered porous journal bearings with slip flow, including the percolation effect under coupled-stress lubrication. But in this paper, all these points are included which made this paper valuable in design purpose.

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