轴承腔内壁油膜运动特性的数值研究

Numerical Study on Motion Characteristics of Lubricating Oil Film of Bearing Chamber Wall

关键词:  航空发动机  轴承腔  两相流动  撞击准则  运动特性  油膜厚度 

Key words:  Aero-engine  Bearing chamber  Two-phase flow  Impingement criteria  Motion characteristics  Oil film thickness

摘要:

为了获得航空发动机轴承腔内壁油膜运动特性,对油滴在轴承腔内运动、油滴/壁面相互作用及油膜的流动进行研究,建立了一套完整的数学计算模型,利用Star-CD商业软件对油膜的运动进行非稳态数值计算,在验证计算模型合理性的基础上,对不同主轴转速下轴承腔两相流动的运动特性进行研究。研究表明:油膜在轴承腔壁面经历从形成到基本稳定的过程。在油膜流动稳定的状态下,随转速的增加,壁面油膜厚度呈减小趋势,而壁面油膜速度却呈增加趋势,油滴撞击油膜动量随转速的增强是主要因素。此外,空气对油膜的剪切作用对油膜流动的加速产生积极作用,且转速越高越显著。 

Abstract:

To obtain the motion characteristics of lubricating oil film of aero-engine bearing chamber wall, oil droplet motion in the bearing chamber, droplet impacts with the chamber wall and oil film flow were studied, and a complete mathematical model was established based on some assumptions. Three-dimensional unsteady numerical simulation to solve oil film flow by using Star-CD commercial software was carried out. On the basis of verifying the rationality of the mathematical model, the motion characteristics of two-phase flow in the bearing chamber with the rotation speed was analyzed and studied. The results show that the oil film on the bearing chamber wall experiences a development process from the oil film formation to basic stability. And in the stable state, with the increasing of rotation speed, oil film thickness shows a trend of decreasing, while oil film circumferential velocity shows a trend of increasing, in which the increment of the oil film momentum by the oil droplets’ impingement is the main reason. Moreover, the shear force between air and oil film has the postive effect on accelerating the oil film velocity .The higher the rotation speed, the effect is more significant. 