Nonlinear transient response of rough symmetric two lobe hole entry hybrid journal bearing system

Abstract

The present paper describes the effect of surface roughness orientation pattern on the nonlinear transient response of symmetric two lobe capillary compensated hole entry hybrid journal bearing. Nonlinear equations of motion have been solved with the Runge-Kutta method. The stability of the journal bearing system has been studied by obtaining the journal center motion trajectories. The results of the study reveal that the surface roughness pattern significantly changes the stability of capillary compensated two lobe hole entry hybrid journal bearing. Hence, from the bearing stability point of view, a proper selection of the surface roughness pattern and bearing geometry is essential.

Behaviour of two-lobe hole-entry hybrid journal bearing system under the combined influence of textured surface and micropolar lubricant

“…the nominal fluid-film thickness of the two-lobe journal bearing is a function of the journal centre co-ordinates ( X ̄ J , Z ̄ J ) and the lobe centre co-ordinates true(trueX¯Li, trueZ¯Litrue). It is described by the following expression (Rahmatabadi et al , 2011; Sharma and Kushare, 2015): where, δ=c1c2 = offset factor (used δ = 1 for the circular journal bearing and δ ≠ 1 for the non-circular journal bearing),…”

“…The linearized equation of disturbed motion of the journal about its equilibrium position is framed by equating the inertia force components to the out-of-balance fluid-film force and the moment components. In the compact form, the linearized equation of motion is describe as (Sharma and Kushare, 2015; Khatri and Sharma, 2016): …”

“…The stability parameter of the journal bearing configuration for the lateral motion is evaluated by using Routh’s stability criteria in terms of critical mass( M ̄ c ). The non-dimensional critical mass( M ̄ c ) is written by Sharma and Kushare (2015) and Khatri and Sharma (2016): where: G ̄ 1 = [ C ̄ 11 C ̄ 22 − C ̄ 21 C ̄ 12 ], …”

“…Further, the threshold speed margin of the journal is calculated in terms of the critical mass ( M ̄ c ) as follows (Crosby and Chetti, 2009; Sharma and Kushare, 2015): where, F ̄ 0 presents the resultant fluid-film reaction at true(∂h¯∂t¯=0true).…”

“…In their investigation, they predicted the journal centre motion trajectory for high-speed rotors supported by two-lobe hydrodynamic oil film journal bearing for three different values of the non-circular ratios. Recently, Sharma and Kushare (2015) examined the effect of rough surface patterns on non-linear journal centre motion trajectories of two-lobe hole-entry hybrid journal bearing configuration. Their study reveals that the two-lobe ( δ = 1.1) journal bearing gives better stability for longitudinally roughened bearing than that of other roughened bearings.…”