An experimental framework for determining wear in porous journal bearings operated in the mixed lubrication regime

Hydrodynamic self-lubricating journal bearings analysis using Rabinowitsch fluid lubricant

Direct ink writing of Pd-Decorated Al2O3 ceramic based catalytic reduction continuous flow reactor

Water as a common contaminant in the lubricating oil can degrade lubricant performance and cause a serious fault of the journal bearing and shorten its service life. Differing from the pure lubricating oil, the contaminated oil with water exhibits a non-Newtonian behavior and has a significant impact on the dynamic performance of the journal bearing. This paper is to establish a relationship between the water contamination and the vibration response of the journal bearing in order to achieve an online condition monitoring of the tribological behaviour of journal bearings. The research progress regarding to the effects of water contamination on the lubrication is firstly reviewed. A theoretical model is then developed for the dependence of the viscosity of the contaminated oil on the shear rate and temperature. The effects of such rheological behavior on the dynamic performance of the journal bearing are also studied. To validate the theoretical analysis, the rheological measurement for the contaminated oil with such water fraction as 0, 1, 3, 5, 7 and 10 per percent by volume, is carried out with the Malvern Bohlin Gemini HRNano rheometer. Those contaminated oil are then fed into the bearing housing. Through accelerometers attached on the housing, vibration responses of the journal bearing are acquired under different working condition. The results outlined that volume water ratios in lubricating oil had the different degrees of effects on the tribological behaviour of journal bearings, which allows early detection of abnormal lubricants to be implemented online vibration responses.

Vibration Analysis of Journal Bearings under Water Contaminated Lubrication

In this paper, the hydrodynamic lubrication of finite porous self-lubricating journal bearings is investigated taking into account the rheological lubricant behavior effect. The modified Reynolds equation is derived by considering both the fluid flow in the porous matrix and the lubricant rheological behavior where Darcy’s law and powerlaw model were used. Governing differential equations were solved numerically using the finite difference method. Static characteristics are obtained by considering three types of lubricants: pseudo-plastic, dilatant and Newtonian fluids. Obtained results showed that the power law index, n, has important effects on the performance of porous and non-porous bearings. An improvement in the fluid bearing characteristics (load capacity, pressure) is observed for dilatant fluids (n>1) while these characteristics decreased for pseudoplastic fluids (n<1). The permeability of the porous structure has significant effects on the performance of porous journal bearings of finite length, particularly at higher eccentricity ratios. Good agreement is observed between the results obtained in this study and those of literature revue.

https://jafmonline.net/JournalArchive/download?file_ID=47560&issue_ID=252

Lubricant Rheological Behavior Effect Analysis on the Performance of Finite Porous Self- Lubricating Journal Bearings

Non-Newtonian effects on porous elastic journal bearings

Multi-Objective Particle Swarm Optimization (MOPSO) algorithm based on the concept of Pareto optimality was used to efficiently evaluate the thermal performance of a conventional adsorption ventilated cooling system. A desiccant wheel numerical model was developed and then coupled to a thermodynamic one in order to predict the different states of airflow through the system components. Instead of the dehumidification performances of the desiccant wheel, the present study focused on optimizing simultaneously the COP and the cooling capacity of the system. The process and regeneration air velocity, the rotational speed of the desiccant wheel and the regeneration temperature were considered as the main initial working parameters to generate the particle swarm within the research space. The results showed that the developed MOPSO algorithm is suitable for this kind of complex optimization problem and allowed, with a minimum computational effort, to generate the Pareto front solutions considered as the best compromises between the objective functions. The use of a purge zone during the optimization process improves the cycle performance mainly by lowering the regeneration heat and the pre-cooling of the process air. The application of MOPSO seems to be useful for the cooling system operators, providing them with a wide choice of operating conditions that will meet the predefined cooling requirements with a better COP. 

A MOPSO algorithm based on pareto dominance concept for comprehensive analysis of a conventional adsorption desiccant cooling system

Purpose




The purpose of this study is to investigate the viscous shear effect on finite porous elastic journal bearings lubricated with non-Newtonian couple stress fluid.




Design/methodology/approach




Based on Stokes micro-continuum mechanics, the modified Reynolds equation including bearing deformation was derived. The porous flow was modeled by the complete Darcy–Brinkman equation. To show the viscous shear effects, bearing characteristics including load capacity and friction factor are compared to those obtained from Darcy model with Beavers–Joseph slip conditions (slip flow model [SFM]) by developing a computer program and discussed for different couple stress values, permeabilities and elastic deformation parameters.




Findings




It is found that the viscous shearing forces effects of the Brinkman model increase the load capacity and friction factor compared to those derived using SFM. Moreover, the couple stresses increase the load capacity while decreasing the friction factor for both models.




Originality/value




This study introduces for the first time the viscous effect on finite porous elastic journal bearings lubricated with couple stress fluid.

Anas Sakim

Papers

Non-Newtonian effects on porous elastic journal bearings

A MOPSO algorithm based on pareto dominance concept for comprehensive analysis of a conventional adsorption desiccant cooling system

Viscous shear effect in non-Newtonian lubrication of finite porous elastic bearings