【作者】 李斌；

【导师】 王锁芳；

【作者基本信息】 南京航空航天大学 ， 环境工程， 2010， 硕士

【摘要】 随着航空发动机整机性能的提高,主轴支点处的轴承腔热负荷也逐渐增加。除轴承滚动体发热量增加外,高温环境通过腔壁和轴承支座等结构对腔内滑油和转子的加热量也明显增加,曾出现腔内滑油过热和着火等问题,直接影响轴承工作性能和发动机可靠性。因此,开展轴承腔内气液两相流动与换热的研究,探索气液混合润滑介质的流动与换热规律是十分必要的。本文对国内外相关研究现状和发展趋势进行了详细分析。以某型发动机后支点轴承腔为研究对象,建立了简化模型的旋转试验台。通过试验研究获得了低转速若干工况轴承腔通风口出气比例和回油口滑油温升随转速的变化规律。应用Fluent软件,采用欧拉双流体模型和代数滑移混合多相流模型分别配合标准k ?ε及RNG k ?ε湍流模型,对试验工况进行数值模拟。与试验结果对比发现:代数滑移混合多相流模型与RNG k ?ε湍流模型配合,能够给出更为合理的轴承腔内气液两相流计算结果。使用该方法,对复杂几何结构轴承腔的若干真实工况进行了数值模拟,获得了主轴转速、密封空气泄漏量及供油量对出油比例与出油温升的影响规律。为了使相关的研究结果和计算方法被工程设计人员方便使用,本文借鉴参数化设计的思想,开发了轴承腔参数化分析平台。该平台集成了Gambit及Fluent软件,能够实现参数化建模、快速划分网格与计算以及计算结果的管理等功能,简化了结构设计者操作计算软件的步骤。由于高转速下轴承腔内壁将出现流动方向与主轴转动方向相同的流动液膜,因此,本文对S.Witting等人建立的轴承腔内壁油膜运动模型进行了详细的推导,开发出相应的计算程序,使用该程序对A.Glahn等人的若干试验工况进行计算,计算结果与试验结果符合较好,表明计算程序的正确,并为后续发展油膜换热模型打下了基础。本文的研究结果,可为轴承腔热设计及航空发动机滑油系统设计提供理论指导和技术储备。更多还原

【Abstract】 With the whole performance of aero-engine increment, the thermal load of bearing chamber at principal axis fulcrum become large. The heat conducted from high temperature surrounding through cavity wall and bearing seat increased besides the heat generated from roll bearing gose up. Many problems such as oil over heated and oil fired have occurred. All of these will affect the working performance of bearing and reliability of aero-engine. So it is very necessary to investigate the air-oil two phase flow in the bearing chamber to obtain the rule of the mixture lubricant flow and heat transfer in the chamber.Based on the analysis of investigations home and aboard, an aero-engine back fulcrum bearing chamber was studied and the simplified test rig was built up. The proportion of air flow through the vent port and the temperature raise of oil pumped out through the scavenge change with different rotate speed were found through the experiment. Based on the algebraic slip mixture model and Euler-Euler model, the commercial computational fluid dynamics software Fluent is introduced to simulate the air-oil two phase flow and heat transfer in teat rig bearing chamber. Compared with test results, it is reliable to use the algebraic slip mixture multiphase model and RNG turbulence model to simulate the multiphase flow. This method was adopted to simulate several real working condition in a complex geometry configuration bearing chamber, and the rule of oil temperature rise, proportion of oil pumped out through different port with the change of shaft rotate speed, air leakage, and oil supply were obstained. In order to make it simple to use the studied result and computational method, a bearing chamber thermal analysis software was developed. Gambit and Fluent were included in this software so as to simplify the designer’s operation. It can achieve many functions, such as modeling, grid generation, fast calculation and results management. The fluid film which has the same flow direction with the shaft rotation was found at high rotate speed. Based on S.Witting’s oil film model, a computing program was developed to investigate the oil film depth and velocity profile. Using this program, some work conditions tested by A.Glahn were carried out. The numerical simulations fit very well with the test results. It is proved that the program is correct and a solid foundation was established to develop further the model of oil film heat transfer.The conclusion in this thesis can provide theoretics and technology for bearing chamber thermal design.更多还原