Numerous published studies on the non-wettable surfaces with surface texture and slip conditions have been reviewed comprehensively to evaluate the performance of hydrodynamic bearings from last two decades. The recent numerical and experimental studies have been explored to observe the individual and combined influence of surface texture and slip. A variety of texture shapes and optimized slip zone profiles have also been discussed in this article. It has been observed from the literature that a suitable combination of modified slip and the conventional no-slip zone is effective in improving dynamic and static performance of hydrodynamic bearings. Many experimental studies also revealed that micro-scale textures are significantly capable of improving the tribological performance. Moreover, slip boundary condition is more beneficial at low and medium eccentricity ratios.

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Implication of Surface Texture and Slip on Hydrodynamic Fluid Film Bearings: A Comprehensive Survey

Analysis of textured journal bearing with slip boundary condition and pseudoplastic lubricants

Surface textures have been widely used in thrust bearings as a means of enhancing the tribological performance. The effect of textures with a spiral distribution on the lubrication characteristics of thrust bearings has not been fully covered. This paper aims to investigate and find the optimal structure and distribution parameters of textures with the maximum loading capacity and minimum friction force as goals.,Combining the multi-objective optimization method based on the non-dominated sorted genetic algorithm-II with response surface methodology, the key textured parameters are optimized. Local sensitivity analysis is used to evaluate the impact level of each parameter.,Spiral distribution of textures can effectively improve the lubrication performance of the thrust bearing compared with the linear distribution. The distribution with high amplitudes and high cycle numbers will weaken the spiral effect and destroy the high-pressure region. Through the multi-objective optimization of the textured structure and distribution parameters, the loading capacity demonstrates a 55.05per cent improvement compared to the basic model. Textured width is the most sensitive parameter for both loading capacity and friction force.,Present research provides a fundamental design guide for textured thrust bearings.

Investigation and optimization of textured thrust bearings with spirally distributed dimples using multi-objective optimization method

This study proposed a systematic approach to evaluating the environmental-economic benefits of multiple air pollution control, CO2 mineralization, and municipal solid waste incineration (MSWI) fly ash stabilization-utilization with high-gravity (HiGee) technology. MSWI fly ash due to its high alkalinity and calcium-rich compositions could be used to absorb acid gas pollutants and mineralize CO2 simultaneously. HiGee system can be deployed to eliminate the mass-transfer limit to accelerate the reaction kinetics. Technical-economic analysis (TEA) and life cycle analysis (LCA) were integrated with the technique to order preference by similarity to ideal solution (TOPSIS) approach and comprehensively evaluate the prioritized alternatives. Compared to existing wet-scrubber and fly ash landfill, the combination of fly ash slurry and further utilization of cementitious material can generate additional profits of direct/indirect carbon credit, calcium carbonate byproduct, reduction of air pollution fees and fly ash utilization revenue. In terms of environmental benefits, the installed HiGee system can reduce water and energy consumption to avoid water depletion and greenhouse gas emissions. TOPSIS results prioritized the various alternatives of HiGee operation modes and provided a technological evaluation for substituting the existing scrubber in an MSWI plant.

A systematic approach to evaluating environmental-economic benefits of high-gravity technology for flue gas purification and municipal solid waste incineration fly ash utilization

Certain (nonpolymeric) fluids show an anomalously low friction when flowing against well-chosen solid walls. We discuss here one possible explanation, postulating that a gaseous film of small thickness h is present between fluid and wall. When h is smaller than the mean free path l of the gas (Knudsen regime), the Navier length b is expected to be independent of h and very large (micrometers).

Fluid/wall slippage

The theory of improving the bearing capacity of fluid lubrication with a heterogeneous slip/no-slip surface has been proposed in recent years, and the extended Reynolds equation is the main...

Experiments on Laminar Flow between Parallel Plates with a Heterogeneous Slip/No-Slip Surface

Tuning surface hybrid-wettability to enhance the vapour film phenomenon induced by boiling heat transfer: Molecular dynamics

A series of experiments is conducted to investigate the hydrodynamic lubricant characteristics of partial surface textured specimens. The specimens are fabricated with partial surface texture. Two dimple shapes are adopted: circular and elliptic. Four kinds of texture arrangements of elliptic dimples are designed. During each test, different rotating speeds and gaps between the tested specimen and the geometric probe are set to explain the relationship between the operation condition and load-carrying capacity. We found that the load-carrying capacity is strongly affected by the operation condition, i.e. by both speed and gap. The surface textured specimens generate large hydrodynamic lift force compared with the untextured specimen. In addition, the texture arrangements exhibit a significant impact on the lubrication property.

Experimental investigation of disc partial surface texture on the generation of hydrodynamic lubricating performance under conformal contact condition

A numerical solution for line contact elastohydrodynamic lubrication (EHL) occurring on the rough surface of heterogeneous materials with a group of particles is presented in this study. The film thickness disturbance caused by particles and roughness is considered into the solution system, and the film pressure between the contact gap generated by the particles and the surface roughness is obtained through a unified Reynold equation system. The inclusions buried in the matrix are made equivalent to areas with the same material as that of the matrix through Eshelby’s equivalent inclusion method and the roughness is characterized by related functions. The results present the effects of different rough topographies combined with the related parameters of the particles on the EHL performance, and the minimum film thickness distribution under different loads, running speeds, and initial viscosities are also investigated. The results show that the roughness morphology and the particles can affect the behavior of the EHL, the traction force on a square rough surface is smaller, and the soft particles have more advantages for improving the EHL performance.

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Analysis of Line Contact Elastohydrodynamic Lubrication with the Particles under Rough Contact Surface

Pin-on-disc experiments are conducted to investigate the tribological performance of untextured and textured brass surfaces with TiN coatings under oil lubrication. The surface texture is designed as a dimple pattern with different diameters and depths for the transverse surfaces of brass pins. After texturing, a TiN coating is deposited through pulsed-bias arc ion plating in a pure N2 atmosphere using a Ti target. Three dimple diameters are used, namely 130 μm, 150 μm, and 170 μm, along with three dimple depths, namely 15 μm, 40 μm, and 60 μm. The TiN coating is around 5 μm thick. Friction tests are conducted under different rotation speeds and loads, and the interfacial adhesion is assessed via a scratch test. Compared to the untextured surface, the textured one offers improved tribological behavior in mixed lubrication because the dimples generate hydrodynamic lift. To reduce friction in the case of higher speed and lower load, the optimum texture parameters are a diameter of 150 μm and a depth of 40 μm.

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Juan Chen

Papers

Experiments on Laminar Flow between Parallel Plates with a Heterogeneous Slip/No-Slip Surface

Tuning surface hybrid-wettability to enhance the vapour film phenomenon induced by boiling heat transfer: Molecular dynamics

Experimental investigation of disc partial surface texture on the generation of hydrodynamic lubricating performance under conformal contact condition

Analysis of Line Contact Elastohydrodynamic Lubrication with the Particles under Rough Contact Surface

Effects of texture geometry on the tribological performance of brass with a TiN coating under lubricated rotation