复层孔隙分布含油轴承的孔道渗流及润滑机制

Seepage flow and lubrication mechanism of oil-bearing with bilayer pore distribution

含油轴承基体中油液的渗流行为对轴承油膜润滑性能影响显著.以不同孔隙率分布的环面复层含油轴承为研究对象,耦合分析轴承系统(包括轴承间隙和多孔轴承内部)的流体流动,基于Darcy定律描述油液渗流行为,并在极坐标下建立含油轴承系统的渗流润滑模型,研究轴承系统中油膜压力的分布规律,分析表面粗糙度、结构参数等对油膜润滑性能的影响.采用粉末冶金工艺制备不同表层孔隙率的复层含油轴承试样,在端面摩擦试验机上开展含油轴承的摩擦学实验,并对数值分析结果进行验证.结果表明,与普通单层含油轴承相比,不同孔隙率分布的复层含油轴承能阻止润滑油液渗入多孔介质,提高轴承润滑性能;随着综合表面均方根粗糙度增大,油膜润滑性能变好,随着表层厚度或表层渗透率增加,油膜润滑性能变差.摩擦实验与润滑理论分析具有相似的结论,验证了所建数值模型的可靠性.研究工作为明晰含油轴承渗流润滑机理及其影响机制提供一定理论依据.

The seepage behavior of oil in the porous bearing has a significant effect on the lubricating performance. Taking the bilayer oil bearing with different porosity as the study object, coupled analysis was accomplished for the fluid flow in the whole bearing system (including bearing clearance and porous bearing interior). The percolation behavior was described based on Darcy’s law. The bilayer oil bearing seepage lubrication model was established in polar coordinates. The pressure distribution law in the bearing system was studied, and the influences of surface roughness and structure parameters on the lubricating performance were analyzed. The bearings with different surface porosity were prepared by powder metallurgy technology. The tribological experiments were carried out on the end-face tester to verify the results of numerical analysis. Results show that compared with ordinary single layer oil bearing, bilayer oil bearing can prevent oil from infiltrating into the porous medium, thus having better lubricating performance. The lubrication performance becomes worse with the increase of the surface thickness or porosity, while it becomes better with the increase of rootmean- square roughness. The results of friction experiment and theory analysis are similar, and the reliability of the model is verified. The research provides a theoretical basis for clarifying the lubrication mechanism and influence mechanism of bilayer oil bearing.