纯滚动条件下单液滴输运过程的试验观察

Observation of Single Oil Droplet Transportation under Pure Rolling Conditions

利用光干涉技术观察球-盘接触纯滚动条件下单个液滴的输运过程,分析该过程中润滑油膜的动态建立过程及组成润滑油膜的不同区域。定义铺展系数来定量分析油滴输运过程中液滴尺寸和速度对润滑性能的影响。结果表明:大液滴低速输运时,铺展系数达到70%以上,说明液滴铺展效应有利于维持润滑时间;而当小液滴快速输运时,铺展系数将低于30%,说明液滴铺展受到局限性。实验进一步观察到当液滴较大时,可在入口区形成一个供油油池,油膜形状与经典润滑油膜外形相似;而当液滴较小且卷吸速度较大时会在接触区中心形成带有"凹陷"的油膜外形。

Transplantation of a single-oil droplet was observed in a pure rolling ball-on-disc contact via an optical inter-ferometry system.The dynamic lubricating processes of film formation and different film regions during transportation were analyzed.A spreading ratio was defined to quantitatively describe the influence of droplet size and speed on lubricating per- formance.The results show that the spreading ratios excesses 70% for large droplet with slow transportation, indicating spreading effect is beneficial for lubrication duration.However, the spreading ratios will be smaller than 30% for the quick transportation of a small droplet, which indicates the limitation of spreading effect. An inlet oil reservoir is found to be formed by a large droplet through experimental observation, which contributes to a classical film shape, whilst a film shape with dimple is obtained by a small droplet with quick passage.