Movement behavior of oil droplet on porous surfaces under the influence of orifice structure
Abstract
Purpose
The lubricating fluid stored in the porous matrix will spontaneously exude to supplement the lubricating film in the damaged area, thus ensuring the long-term self-lubricating function of the porous surface. To reveal the repair mechanism of oil film, it is necessary to understand the flow characteristics of oil in micropores. The purpose of this study guides the design of micropore structure to realize the rapid exudation of oil to the porous surface and the rapid repair of the lubricating film.
Design/methodology/approach
In this paper, cylindrical orifice, convergent orifice and divergent orifice were studied. The numerical model of lubricating oil exudation in micropores was established. The distribution characteristics of oil pressure, velocity and three-phase contact line in the process of oil exudation were investigated. The effects of different orifice shapes and orifice structure parameters on the pinning and spreading characteristics of oil droplet were analyzed. Then the internal mechanisms of oil droplet formation and spread on the orifice surface were summarized.
Findings
The results show that during the process of oil exudation, the three-phase contact line of the oil drop is pinned once at the edge of the cylindrical and convergent orifice. Compared with the three orifice structures, the inlet pressure of the oil drop is low, and the oil velocity at the pinning point is stable in the divergent orifice. Resulting in favorable oil exudation. It is easier for oil droplet to depin by appropriately reducing the wall wetting angle, increasing the aperture or controlling the wall inclination angle. Ensure the self-healing and long-lasting lubrication film of porous oil-bearing surfaces.
Practical implications
The effect of pore structure on the flow behavior of lubricating fluid has always been concerned. But the mechanism by which different orifice shape affect the pinning behavior of oil droplets is not yet clear, which is crucial for understanding the self-healing mechanism of oil films on porous surfaces. It is meaningful to analyze the mechanism of oil exudation and spreading on the porous surface of oil in the special orifice, to optimize the design of the orifice structure.
Originality/value
Orifice shape has influence on internal flow field parameters. There is no report on the influence of orifice shape on the film formation process of oil seepage and diffusion from pores. The effects of different orifice shapes and orifice structure parameters on the characteristics of oil droplet pinning and diffusion were studied.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0118/
Keywords
Acknowledgements
The authors are very grateful for the support of the National Natural Science Foundation of China (52005005, 51975005), the Tribology Science Fund of State Key Laboratory of Tribology in Advanced Equipment (SKLTKF22B05, SKLTKF23B04) and China International Science and Technology Cooperation Base on Intelligent Equipment Manufacturing in Special Service Environment (ISTC2021KF06, ISTC2022KF02).
Declaration of Interest Statement: The authors declare that there are no conflicts of interest regarding the publication of this paper.
Citation
Zhang, G., Zhang, Z., Wang, Z., Sun, Y., Tong, B. and Tu, D. (2024), "Movement behavior of oil droplet on porous surfaces under the influence of orifice structure", Industrial Lubrication and Tribology, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/ILT-04-2024-0118
Publisher
:Emerald Publishing Limited
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