运动油滴/固体壁面斜碰撞的状态辨识及特征分析

 航空发动机轴承腔油气两相流动与换热研究是轴承腔润滑与换热设计的重要基础工作,而运动油滴与轴承腔壁面的碰撞状态辨识及特征分析是轴承腔油气两相流动与换热研究的组成部分。基于VOF方法建立了运动油滴与固体壁面斜碰撞数值仿真模型,实现了运动油滴与固体壁面斜碰撞状态的数值模拟,分析了碰撞油滴直径、入射角和碰撞速度对沉积油膜铺展长度、油膜堆积厚度和溅射油滴数目等碰撞状态特征参数的影响规律,提出了运动油滴与固体壁面斜碰撞条件下的状态判断准则,并得到了文献的物理试验工作的支持。研究结果表明:随着油滴入射角减小,沉积油膜铺展长度和油膜堆积厚度增大,溅射油滴数目减少;随着碰撞速度和油滴直径的增大,沉积油膜铺展长度和溅射油滴数目均增大,但油膜堆积厚度对应前者呈减小趋势、对应后者仍呈增大趋势。

State identification and characteristics analysis of oil droplet's oblique impact onto solid wall

Analysis of oil/air two-phase flow and heat transfer in bearing chamber are important fundamental work for the lubrication and heat transfer design of aeroengine bearing chamber, while state identification and characteristics analysis of oil droplet''s oblique impact onto solid wall are the main parts for oil/air two-phase flow and heat transfer study. In this paper, the numerical model of oil droplet''s oblique impact onto solid wall is established with volume of fluid (VOF) method and the numerical simulation of oil droplet impingement state is carried out, and then the effects of oil droplet diameter, incident angle, impact velocity on the deposited oil film spreading length, oil film thickness and splashing droplets number are discussed particularly, the criterion used for classify impingement state of oil droplet oblique impingement is proposed, and its rationality is verified by physical testing work of others. The results show that as the incident angle decreases, the deposited oil film spreading length and oil film thickness increase, whereas the number of splashing droplets reduces; as the impact velocity and oil droplet diameter increase, the deposited oil film spreading length and the splashing droplets number increase, but the oil film thickness decreasing trend corresponds to the former and the increasing trend corresponds to the latter.