As one of the important friction pairs of a diesel engine, the cylinder-liner piston ring (CL-PR) faces a harsh high-temperature working environment. To explore the mapping relationship between the friction performance of the CL-PR and the change in temperature, the reciprocating-friction and wear-testing machine was used to analyze the friction performance and lubrication performance of four kinds of lubricating oil at different temperatures (room temperature, 60 °C, 90 °C, and 120 °C) from the friction coefficient, contact resistance and surface topography. The results show that the tribological properties of the four lubricating oils show different trends with the increase in temperature. The friction coefficient of the base oil first decreases and then increases with the increase in temperature; this shows that the friction property of the base oil is improved by a certain temperature rise, and the increase in temperature promotes the formation of an oxide film and reduces the friction coefficient. While the friction coefficient of other three lubricating oils with specific application scenarios increases first and then remains stable, the wear of the friction pair is the most severe at 120 °C. The wear forms are abrasive wear and adhesive wear.

A xenon induced fluorescence technique is used to measure the water film thickness of a rubber-supported water-lubricated tilting pad thrust bearing (RWTB). Film thickness maps are obtained over a range of speeds and loads. Based on a Thermo-Elasto-Hydrodynamic lubrication model, the calculated film thickness is compared with the measured one. The measurement shows that the lubrication regime of the RWTB can be observed and it can form a convergent wedge of lubricant. The calculated results are on par with the experimental results at low speed condition (200 r · min ⁻¹ ). Generally, the calculated film thickness is larger and the discrepancy between them increases respecting to the speed. The RWTB is in the hydrodynamic lubrication regime when the speed is over 200 r · min ⁻¹ and the load is less than 0.25 MPa. The comparison between the measurements and calculations verifies that the fluorescence technique can be used to measure the film thickness of water-lubricated thrust bearings.

A numerical three-dimensional computational fluid dynamics-fluid structure interaction (CFD-FSI) model including lining deformation and cavitation is developed to evaluate the effect of perturbation amplitudes on stiffness coefficients of hydrodynamic water-lubricated plain journal bearings. Three types of bearing with rubber, polymer and steel lining materials are compared in terms of stiffness coefficients, load-carrying capacity and journal center equilibrium position under different eccentricity (ɛ) conditions. The simulation results indicate that perturbation amplitudes have great influence on the four stiffness coefficients of water film of hard lining bearings at large ɛ. However, when ɛ ≤ 0.5 and the perturbation varies within 2.9% of the bearing radial clearance, the effect is less than 10% regardless the lining materials. For the rubber lining bearing, the effect of perturbation amplitudes on the stiffness coefficients is negligible due to the rubber deformation, even at ɛ = 1.9 and the perturbation amplitudes up to 7% of the radial clearance. Lining deformation also affects the attitude angle of the journal and the stiffness of water film. The calculation results demonstrate that the lining deformation and journal perturbation amplitudes are two important factors which cannot be ignored in the calculation of bearing stiffness in case of the journal at large eccentricity ratios.

In order to study the effect of surface roughness on lubrication performance of an elastic support water-lubricated tilting pad thrust bearing, a mixed lubrication (ML) deterministic model is hereby presented based on a unified Reynolds equation model. This very model incorporates the elastic–plastic deformation of asperities and polymer matrix of the thrust pad, as well as the elastic deformation of the rubber support. The randomly distributed surface roughness of the thrust pad is generated by a mathematical model and shares the same distribution characteristics as the measured surface roughness. The Greenwood and Williamson asperity contact model and thin plate deformation model are combined to solve the asperities contact stress and deformation. Meanwhile, the bearing ML performance is compared with the results calculated by a thermohydrodynamic (THD) lubrication model and a thermo-elasto-hydrodynamic (TEHD) lubrication model, while the film thickness is also compared with measurements. The results show that the water film thickness calculated by the ML model is smaller than that by the THD model and the TEHD model, but the water film temperature is higher. The roughness has a great influence on the contact area ratio and the lubrication state, but little effect on the average film thickness. A higher roughness indicates a higher rotational speed required for the bearing to achieve full hydrodynamic lubrication. The film thickness calculated by the mixed lubrication model is closer to the measured results. Overall, it is proved that the mixed lubrication model can more accurately predict the lubrication performance of bearings. Compared to the thin plate deformation model, the elastic deformation simulation based on the half-infinite space model severely overestimates the elastic deformation of the pad surface, making it unsuitable for calculating the elastic deformation of the polymer matrix of the thrust pad under contact force or water film pressure. This ML deterministic model provides an effective means for high-precision prediction of the lubrication performance of the elastic supported water-lubricated thrust bearings coupled with multi-layer soft materials.