Purpose -In recent years, researchers have focused a great deal of attention on multirecess hybrid journal bearing systems. The non-circular journal bearings are widely used in industry on account of their better stability, simplicity, efficiency and low cost. The purpose of this paper is to present a theoretical investigation into the performance of a two-lobe multirecess hybrid journal bearing system. Design/methodology/approach -The Reynold's equation governing the lubricant flow in the clearance space between the journal and bearing together with restrictor flow equations has been solved using finite element method. The bearing static and dynamic performance characteristics have been presented for the various values of the offset factors (0.75, 1, 1.25 and 1.50) for the hybrid mode of operation of the journal bearing system compensated by capillary and orifice restrictors for the commonly used bearing operating and geometric parameters. The offset of the journal has been accounted for by defining a non-dimensional factor called offset factor delta. Findings -The numerically simulated results indicate that a two-lobe four recessed hybrid journal bearing provides a better performance than the corresponding similar circular recessed journal bearing system. The study further reveals that in order to get an improved performance of a two-lobe four recessed journal bearing, a proper selection of bearing offset factors along with type of restrictor (capillary or orifice) is essential. Originality/value -The results presented in this paper are useful for bearing designers.
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.
The present paper is aimed to investigate theoretically the effect of non-linear behavior of the lubricant on the performance of an orifice compensated two lobe non recessed worn hybrid journal bearing. A non-linear behavior of lubricating oil is modeled by using the cubic shear stress law. Dufrane’s abrasive model has been used for the analysis of wear damage on the bearing surface. A modified form of Reynolds' equation is solved by using finite element method (FEM) taking into account the relation between shear stress and shear strain rate. The influence of non-linearity factor ([Formula: see text]) and the wear depth parameter ([Formula: see text]) on the bearing performance of a two lobe non recessed hybrid journal bearing is presented for the different values of the offset factor ( δ = 0.80, 1.0 and 1.20). The numerically simulated results indicate that the direct fluid-film stiffness coefficients [Formula: see text] and [Formula: see text] of worn symmetric bearing configuration ( δ = 1.20) operated with non-Newtonian lubricant are reduced about 30% and 18%, respectively, vis-à-vis the circular unworn hole entry journal bearing lubricated with Newtonian lubricant. Further, it is also noticed that two lobe non recessed worn hybrid journal bearing with offset factor greater than one results in an enhancement by the order of 11% in the value of [Formula: see text] and 6% in the value of [Formula: see text] as compared to circular worn symmetric hybrid journal bearing operated with non-Newtonian lubricant. The bearing with offset factor less than one is prevailingly suffering by the non-linear behavior of lubricant and wear defect.
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