Thermohydrostatic rheological analysis of constant flow valve compensated multiple hole-entry hybrid journal bearings

Abstract

Purpose -The changing technological scenario necessitated hybrid journal bearings to operate under severe conditions of heavy load and high speed resulting into temperature rise of the lubricant fluid-film and bearing surface. To predict the performance of a bearing realistically, theoretical model must consider the combined influence of the rise of temperature and non-Newtonian behavior of the lubricant. The aim of the present paper is to study the effect of viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on performance of constant flow valve compensated multiple hole-entry hybrid journal bearings. Design/methodology/approach -Finite element method has been used to solve Reynolds equation along with restrictor flow equation, 3D energy equation and 3D conduction equation using suitable iterative technique. The non-Newtonian lubricant has been assumed to follow cubic shear stress law. Findings -The thermohydrostatic rheological performances of symmetric and asymmetric hole-entry hybrid journal bearing configurations are studied. The computed results illustrate that variation of viscosity due to rise in temperature and non-Newtonian behavior of the lubricant affects the performance of hole-entry hybrid journal bearing system quite significantly. Originality/value -In the present work, the influences of the viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on the performance characteristics of non-recessed hole-entry hybrid journal bearing with symmetric and asymmetric configurations compensated with constant flow valve restrictors have been investigated for generating the design data to be used by bearing designer. The design data computed in the present thesis are a contribution in field of knowledge of bearing design. NomenclatureDimensional parametersThe current issue and full text archive of this journal is available at Subscripts and superscriptsstate condition ori ¼ orifice p ¼ parameter due to pressure R ¼ restrictor r ¼ reference value s ¼ supply pressure T ¼ parameter due to temperature, transpose of matrix x, y, z ¼ components in X, Y and Z directions * ¼ concentric operation · ¼ first derivative w.r.t. time · · ¼ second derivative w.r.t. time Abbreviations CFV ¼ constant flow valve FEM ¼ finite element method THS ¼ thermohydrostatic

A study of 2-lobe symmetric hole entry hybrid journal bearing operating with non-Newtonian lubricant considering thermal effects

“…The modified form of Reynolds equation governing the flow of non-Newtonian lubricant flow field (laminar and incompressible) for 2-lobe journal bearing is expressed in non-dimensional form as [13,18,[29][30][31]34]:…”

“…The cubic law fluid model is defined in non-dimensional form by the following relations [11,15,18,29,34]:…”

“…The 3-D energy equation is used to obtain fluid-film temperature distribution in the fluid domain and is written in non-dimensional form as [20,21,23,[25][26][27]34]:…”

“…Very recently, Garg et al [29] examined the influence of nonlinear behavior of lubricant due to the addition of additives and rise in temperature of fluid film on the performance of circular multiple entry journal bearing. Further, they [30,34] investigated the effect of temperature rise on performance of circular non-recessed hybrid journal bearing compensated with different types of restrictors. The results of the studies [29,30,34] indicate that the performance of journal bearings is affected quite significantly because of temperature rise of lubricant film.…”

“…Further, they [30,34] investigated the effect of temperature rise on performance of circular non-recessed hybrid journal bearing compensated with different types of restrictors. The results of the studies [29,30,34] indicate that the performance of journal bearings is affected quite significantly because of temperature rise of lubricant film. Therefore, it becomes imperative to consider the thermal effect in the analysis to envisage the factual performance of bearing system.…”