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Study on Reduction of Oil Content in Porous Journal Bearings with Running Time and Effect of the Reduced Oil Content on Lubrication Characteristics

多孔轴颈轴承含油量随运行时间降低的研究以及含油量降低对润滑特性的影响

基本信息

批准号：
06650167
负责人：
KANEKO Satoru
金额：
$ 1.28万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

In actual applications, porous bearings are usually lubricated only by the oil initially provided within their structures. With running time, the oil content decreases mainly due to leakage and the oil loss yields variation of performance characteristics such as the frictional coefficient. In the present study, the reduction of oil content in the porous matrix and its effect on the frictional characteristics were investigated theoretically and experimentally. The pressure distributions in the oil film and the porous matrix were calculated by simultaneously solving the modified Reynolds equation including a so-called filter term and the Laplace equation derived from Darcy's law. These equations were made discrete using the cell method and the VOF (volume of fluid) method. The VOF method is applicable to discretization of the region including a boundary surface between oil and air which penetrates into the porous matrix with reduction of oil content. The difference equations derived from … More this discretization were solved by successive over-relaxation method. The circumferential boundary conditions for the oil-film pressure were given by the integral momentum equation based on the momentum theorem and the continuity equation based a balance of the oil -loss rate in the porous matrix and the oil leakage flow rate from the axial ends through the bearing clearance. Experiments were also conducted using a model bearing whose porous matrix was made of the packed glass spheres having small uniform diameter to observe the region where the oil reduction occurs and its pattern spreading into the porous matrix with running time.The results were summarized as follows :(1) The oil reduction occurs at the position near the trailing end of the oil-film extent. The oil reduced region in the porous matrix spreads to the radial direction and to the direction of the shaft rotation with running time, whose patterns obtained by the experiment and by the numerical analysis qualitatively agrees with each other.(2) The coefficient of friction obtained from the calculation increases with the reduction of oil content in the porous matrix.(3) The reduction rate of oil content in the porous matrix increases with the permeability of the porous matrix. This effect of the permeability is obtained both from the experimental results and from the computed results. Less

在实际应用中，多孔轴承通常只由其结构中最初提供的油来润滑。随着运行时间的延长，含油量的下降主要是由于泄漏和油损引起的摩擦系数等性能特性的变化。本文从理论和实验两方面研究了多孔基质中含油量的降低及其对摩擦特性的影响。通过同时求解含有所谓过滤项的修正雷诺方程和由达西定律导出的拉普拉斯方程，计算了油膜和多孔基质中的压力分布。这些方程用格子法和VOF(流体体积)法离散。VOF方法适用于含油气界面区域的离散化，该界面随着含油量的降低而穿透到多孔介质中。由…导出的差分方程组并用逐次超松弛法进行了离散。油膜压力的周向边界条件由基于动量定理的积分动量方程和基于平衡多孔介质中的油损率和从轴端通过轴承间隙的漏油流量的连续性方程给出。实验还利用均匀直径较小的填充玻璃球为多孔基质的模型轴承进行了实验，观察了减油发生的区域及其随运行时间向多孔基质中扩散的规律。随着运行时间的延长，多孔基质中的减油区向径向和轴旋转方向扩展，实验和数值分析得到的规律定性地吻合。(2)计算得到的摩擦系数随着多孔基质中含油量的减少而增大。(3)多孔基质中含油量的降低速率随着多孔基质渗透率的增加而增加。这种渗透率效应既可以从实验结果中得到，也可以从计算结果中得到。较少