On the squeeze film lubrication of rough short porous partial journal bearings with micropolar fluids

Abstract

In this article, a theoretical study of the effect of surface roughness on the squeeze film characteristics of short porous partial journal bearing lubricated with micropolar fluids is made. The modified averaged Reynolds equation accounting for the randomized surface roughness structure is mathematically derived. The Christensen stochastic theory of hydrodynamic lubrication of a rough surface is used to study the effect of two types of one-dimensional (1D) surface roughness on the squeeze film characteristics of a short porous partial journal bearing with micropolar fluid. It is assumed that the roughness asperity heights are small compared to the film thickness. It is observed that the transverse surface roughness pattern improves the squeeze film characteristics, whereas the squeeze film bearing performance is affected due to the presence of 1D longitudinal surface roughness. These effects are more pronounced for the micropolar fluids.

Theoretical analysis of single-layered porous short journal bearing under the lubrication of micropolar fluid

“…Inside the porous layer, the micropolar fluid forms a hydrodynamic film of lubrication to sustain the load. The following assumptions [1][2][3][4][5][6][7] are vital for developing the modified Reynolds equation in case of a porous journal bearing under micropolar lubrication. Here, w, p s , p * , p, e, H and h denoted load, supply pressure, fluid pressure inside porous layer, fluid film pressure, eccentricity, porous layer thickness and fluid film thickness, respectively.…”

“…the law of conservation of linear momentum, mass and angular momentum. Secondly, the modified Darcy's law [5,13] gives the governing equation for the micropolar fluid flow through the porous medium, which is as follows:…”

“…where q is the modified Darcy velocity, k is the porous medium permeability, is the absolute viscosity, ℶ is the Assuming H is very small as compared to r b and using the pressure continuity condition for y = 0 (p = p * ) and the boundary condition of rigid impermeable housing at y = − H, then p * y = 0 . Now, according to the modified Darcy's law [5,13], the velocity component at y = 0 is given by, According to the micropolar lubrication theory [1,2] and the modified Darcy's law [5,13], the other two velocity components can be expressed as:…”

“…As reported by the short porous journal bearing approximation [5], the changes in the circumferential component of pressure are ignored as compared with an axial component of pressure changes. So, the reduced form of modified Reynolds Eq.…”

“…Shukla et al [3] and Verma et al [4] investigated the performance of one-dimensional slider bearing and porous slider bearing by developing the generalised Reynolds equation for micropolar fluid. Naduvinamani et al [5] reported the effect of surface roughness and the micropolar fluid lubrication on the performance of rough short porous partial journal bearing under squeeze film lubrication and found that the micropolar lubricant consists of suspended and contaminated particles as an additive, due to which micropolar lubricant gives more resistance to the journal motion as of the Newtonian lubricants. It withstands the load for a more extended period for the single-layered porous journal bearing.…”