Performance Characteristics of Two-Lobe Bearings Operating with Non-Newtonian Lubricants

Abstract

This study presents a steady state and transient solution for a finite width two-lobe bearing operating with a non-Newtonian lubricant, obeying the power law model. A non-linear time-transient analysis is carried out and the orbital stability of journal is ensured by solving the equation of motion by fourth order Runge-Kutta method. Using the expressions for eccentricity ratio of lower and upper lobes and film thickness for each lobe, the modified Reynolds equation is solved separately for each lobe by finite difference technique with a successive over-relaxation scheme. Performance parameters of two-lobe bearing like load carrying capacity, Sommerfeld number, attitude angle; flow and friction parameter are determined and compared with the established results for Newtonian lubricants. Stability parameters are compared with circular bearings. It is found that the non-Newtonian effects are very prominent in the determination of load capacity, flow and friction characteristics of two-lobe bearings. Stability parameters of two-lobe bearings are considerably higher for all eccentricity ratios compared to circular bearings; hence these bearings are better suited for applications where whirl instability limits the speed at which the bearing can be operated.

Stability Analysis of a Lemon Bearing Operating with Non-Newtonian Lubricant Considering Slip between the Sliding Surfaces

“…. [18] where 𝜇 ′ is the amended viscosity, m is the pseudoplastic viscosity constant, U is the velocity of the journal. Since the power-law model is applicable only for shear-thinning liquids (n < 1), calculations are applicable and done only for powerlaw index (PLI), n < 1.…”

“…Under dynamic conditions, the modified Reynolds equation for pressure distribution in the bearing clearance lubricated with a non-Newtonian lubricant involving wall-slip can be expressed as Eq. (18).…”

“…According to his research, the load-bearing capacity and pressure increased as the power-law index grew, and the power-law index had a more substantial influence at higher eccentricity ratios. Researchers [17,18] found the power-law model to be more effective and well-suited in analyzing an elliptical bore bearing's performance characteristic with non-Newtonian liquids than the other available modes for examining non-Newtonian fluids. According to Crosby and Chetti, [19] the parameter of couple stress (non-Newtonian fluid) has a considerable impact on bearing performance when compared to Newtonian fluids, resulting in greater stability.…”

“…To summarise the gaps in previous research studies, it is surveyed that in earlier works, researchers focused on the influence of non-Newtonian lubricant on the performance of plain circular bearings [9][10][11]17] or two-lobe bearings. [13][14][15][16][17][18]21] Other studies [1][2] concentrated only on the effect of slip on plain journal bearings or two-lobe bearings. [19] Also, to add to the above gaps, Recently, Das and roy [22] investigated the influence of non-Newtonian lubricant on multilobe bearings, and Rao et al [27] investigated the effect of partial slip with texturing on multilobe bearings using Newtonian fluids.…”