轴承腔中油滴尺寸分布和沉积特性

Oil Droplet Size Distribution and Deposition Properties in Bearing Chamber

航空发动机的润滑系统和二次空气流动系统的设计依赖于对轴承腔中复杂的油气两相流动状态的理解,这其中包括影响轴承腔润滑和换热性能的壁面油膜物理特性。运动油滴转移的质量和动量与轴承腔壁面油膜厚度和速度有很大关系,并决定轴承腔油气两相流动的油膜初始状态。通过分析轴承腔结构工况与油滴直径分布参数关系,明晰基于直径尺寸连续的油滴质量分布,在此基础上进行油滴与轴承腔壁面碰撞后的沉积质量和转移动量的计算,以量纲一参数的形式探讨轴承腔结构和工况对油滴沉积质量和转移动量的影响。针对某一轴承腔结构和工况条件进行的油滴沉积质量和动量转移量计算,以研究计算方法的可行性。结合油滴尺寸分布进行油滴沉积特性分析,探索轴承腔油膜形成过程的物理本质,获得表征轴承腔结构和工况条件的量纲一参数W e*1/2对油滴沉积质量和沉积油膜动量转移量的影响规律,有助于航空发动机轴承腔油气两相流动研究后续工作的开展。

The design of secondary air flow system and lubrication system of aeroengine is dependent on an understanding of complex oil/air two-phase flow state in bearing chambers,including wall oil film physical property which influences the lubrication and heat transfer performance of bearing chambers.The mass and momentum of oil droplet transfer are closely correlated with wall oil film thickness and velocity,and determine the initial film state under oil/air two-phase flow condition in bearing chambers.Through analyzing the correlation of oil droplet diameter distribution parameters with the chamber geometry and relevant operating conditions,and droplet mass distribution based on continuous diameters is obtained.Then deposited mass and transfer momentum upon droplets/wall impact are calculated.Influences of geometry and operating conditions on deposited mass and transfer momentum are discussed in the form of dimension-parameter.The feasibility of the calculation method is investigated by using a certain bearing chamber model under relevant operating conditions.The studies on deposition properties in combination with droplet diameter distribution and physical characteristics of oil film formation process,as well as the influence law of dimension-parameter on deposited mass and transfer momentum,contribute to follow-up research work on oil/air two-phase flow in aero engine bearing chambers.