Gengyuan Gao

Analysis on design parameters of water-lubricated journal bearings under hydrodynamic lubrication

The article aims to investigate the relationship between eccentricity ratio and the Sommerfeld number based on hydrodynamic water-lubricated journal bearings. Considering the differences between water and oil, especially the difference in vapor pressure, the effect of cavitation on pressure distribution of water film is analyzed based on three boundary conditions and a cavitation model by computational fluid dynamics (CFD). The result shows that the three boundary conditions are all not suitable to replace cavitation model in numerical analysis of water-lubricated journal bearings. Then numerical analysis of journal bearings with different dimensions is undertaken with the cavitation model under different working conditions. Based on the analysis, a reference is produced for designing water-lubricated journal bearings under hydrodynamic lubrication. At last, the reference is verified by experiments.

Study of the lubrication performance of water-lubricated journal bearings with CFD and FSI method

Purpose Water lubrication is significant for its environmental friendliness. Composite journal bearing is liable to deform for the huge pressure of water film. This paper aims to study the influence of elastic deformation on how lubrication functions in water-lubricated journal bearings and to provide references for designing composite journal bearings. Design/methodology/approach The combination of computational fluid dynamics and fluid-structure interaction is adopted in this paper to study the lubrication performance of water-lubricated compliant journal bearings. The influences of elasticity modulus and Poisson’s ratio on load-carrying capacity and elastic deformation are studied for different rotational speeds. Predictions in this work are compared with the published experimental results, and the present work agrees well with the experimental results. Findings A reference whether elastic deformation should be considered for composite journal bearings is proposed under different working conditions. Besides, a reference to determine water-lubricated plain journal bearings dimensions under different loads and rotational speeds is developed with the effect of both elastic deformation and cavitation being accounted. Originality/value The present research provides references as to whether elastic deformation should be considered in operation and to determine compliant journal bearings’ dimensions in the design process.

Design and analysis of a self-lubricating nuclear joint bearing above 320°C

Purpose The purpose of this study was to solve the problem of most woven-fabric self-lubricating bearings that find it difficult to function at temperatures above 320°C, by designing a new type of new nuclear joint bearing. The results of this study will help designers to achieve accurate stress distribution, displacement deformation, fatigue life and damage of bearings. All of these can be a guide for designing self-lubricating joint bearings. Design/methodology/approach Finite element analysis is undertaken to simulate the new design bearings. To get the most appropriate and accurate results, the room temperature simulation (Simulation A), the modulus of elasticity that changes with temperature (Simulation B) and the thermal-structure-coupled simulation (Simulation C) are compared. The fatigue simulation is conducted to verify whether the self-lubricating method is reasonable and whether the bearing can function for over 60 years in an enclosed environment. Findings Stress distribution and displacement deformation of joint bearing can be accurately achieved via the thermal-structure coupled simulation. Work life and damage results have been achieved via the fatigue analysis, and the suggested working loads can be calculated via safety factors. Originality/value The newly designed joint bearing in which the graphite is laid on the outside of the inner ring functions and self-lubricates at temperatures above 320°C.

Tribological behaviors of UHMWPE composites with different counter surface morphologies

The influence of counter surface morphologies on hybrid glass fiber (GF) and carbon fiber (CF) filled ultrahigh molecular weight polyethylene (UHMWPE) were studied under various contact pressure and sliding speed against GCr15 steel in dry condition. The goals were to investigate the tribological behavior of GF/CF/UHMWPE composite as a kind of water lubricated journal bearing material. The friction and wear behavior of composites were examined using a pin-on-disc tribometer. The morphologies of the worn surface were examined by scanning electron microscopy (SEM) and laser 3D micro-imaging and profile measurement. Generally, the wear rate and friction coefficient of composites increase as the increment of counter surface roughness. The friction coefficient increases firstly and then decrease with an increase in sliding speed and contact pressure for counterface with Ra=0.2 and 3.5 μm, while the friction coefficient decreased for counterface with Ra=0.6 μm.