Purpose
Micro-surface texturing is emerging as a possible way to enhance the tribological performance of hydrodynamic fluid film bearings. In view of this, numerical simulations are carried out to examine the influence of surface texture on performance of hybrid thrust bearing system. This paper aims to determine optimum attributes of micro-grooves for thrust bearing operating in hybrid mode.
Design/methodology/approach
An iterative source code based on finite element formulation of Reynolds equation has been developed to numerically simulate flow of lubricant through the bearing. Mass-conserving algorithm based on Jakobsson–Floberg–Olsson (JFO) condition has been used to numerically capture cavitation phenomenon in the bearing. Gauss Siedel method has been used to obtain steady state performance parameters of the bearings.
Findings
A parametric study has been performed to improve the load supporting capacity of the bearing by optimizing micro-groove attributes and configuration. It is noticed that use of full-section micro-groove is beneficial in improving the efficiency of bearing by enhancing the fluid film reaction and reducing the film frictional power losses.
Originality/value
This study is helpful in examining the usefulness of micro-groove textured surfaces in hybrid thrust bearing applications.
Purpose
The porous bearings are commonly used in slider thrust bearings owing to their self-lubricating properties and cost effectiveness as compared to conventional hydrodynamic bearings. The purpose of this paper is to numerically investigate usefulness of porous layer in hydrostatic thrust bearing operating with magnetic fluid. The effect of magnetic field and permeability has been analysed on steady-state (film pressure, film reaction and lubricant flow rate) and rotor-dynamic (stiffness and damping) parameters of bearing.
Design/methodology/approach
Finite element approach is used to obtain numerical solution of flow governing equations (Magneto-hydrodynamics Reynolds equation, Darcy law and capillary equation) for computing abovementioned performance indices. Finite element method formulation converts elliptical Reynolds equation into set of algebraic equation that are solved using Gauss–Seidel method.
Findings
It has been reported that porosity has limited but adverse effects on performance parameters of bearing. The adverse effects of porosity can be minimized by using a circular pocket for achieving better steady-state response and an annular/elliptical pocket, for having better rotor-dynamic response. The use of magnetic fluid is found to be substantially enhancing the fluid film reaction (53%) and damping parameters (55%).
Practical implications
The present work recommends use of circular pocket for achieving better steady-state performance indices. However, annular and elliptical pockets should be preferred, when design criteria for the bearing are better rotor-dynamic performance.
Originality/value
This study deals with influence of magnetic fluid, porosity and pocket shape on rotor-dynamic performance of externally pressurized thrust bearing.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0289/
This article deals with the steady and dynamic performance analysis of rough surface circular and multi-lobe journal bearings operating with non-Newtonian lubricant in turbulent regimes. The numerical solution of Reynold's equation was obtained using the finite element method. To account for surface roughness, the Patir and Cheng model was used, and fluid turbulent behavior was modeled using the turbulent theory as proposed by Ng and Pan. The non-Newtonian behavior of the lubricant is presented by the Rabinowitsch fluid model, and JFO boundary conditions are used to solve Reynold's equation, considering gaseous cavitation. The bearing with micro-roughness has been considered in numerical analysis and transverse roughness has been reported to improve bearing performance indices. Among the different bearing design configurations, the two-lobe bearing configuration provides significantly improves the minimum film thickness, hydrodynamic pressure, and dynamic parameters. The presence of turbulent flow and transverse surface roughness produces a synergistic effect that enhances the minimum film thickness, stiffness, and damping parameters of journal bearings. This study provides a detailed comparison between various bearing designs and recommends the use of two-lobe bearings for high-speed applications.
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