航空发动机气膜浮环密封上浮性能研究

为研究气膜浮环的上浮性能,针对航空发动机主轴承箱的气膜浮环密封系统,建立浮环的有限元模型并提出一种上浮转速的计算方法。采用Ansys建立密封组件的有限元模型,提取浮环与跑道的径向变形,得到浮环密封的动态间隙。采用Fluent建立浮环密封偏心气膜模型,提出浮环上浮转速与泄漏率的计算流程。在先增压至工作压力再增速和先增速到工作转速再增压2种操作条件下分析各结构参数、操作参数对浮环上浮转速的影响,并搭建试验台进行试验验证。结果表明:低压差下气膜浮环的泄漏率与偏心率呈近似二次关系,上浮力随偏心率增大而增大但会有一个畸变过程;在保证密封性能的前提下工程设计时应选取较小的波簧弹力,较大的节流长度。不同的操作方式下各密封参数对气膜浮环上浮性能的影响呈现很大的差异性,综合来说先增速后增压时上浮性能较好,有条件时开车前应先进行上浮性能的分析再选择操作条件施加的顺序。

Research on Floating Performance of Aeroengine Air Film Floating Ring Seal

In order to study the floating performance of the air film floating ring,the finite element model of floating ring was established and a calculation method of the floating speed was proposed.The finite element model of the seal assembly was established by using Ansys,the radial deformation of the floating ring and the runway was extracted to obtain the dynamic gap of the floating ring seal.The eccentric air film model of the floating ring seal was established by using Fluent,and the calculation process of the floating ring floating speed and leakage rate was proposed.The influence of structural parameters and operating parameters on floating ring floating was analyzed under two operating conditions,first increasing pressure to working pressure and then increasing speed,and first increasing speed to working speed and then increasing pressure,and a test bench was set up for testing verification.The results show that the leakage rate of the air membrane floating ring and the eccentricity under a low pressure difference have an approximately quadratic relationship,and the upward buoyancy is increased with the increase of the eccentricity but there is a distortion process.Under the premise of ensuring the sealing performance,a smaller wave spring elastic force and a larger throttling length should be selected when engineering design.The effects of various sealing parameters on the floating performance of the air film floating ring under different operating modes are very different.In general,the floating performance is better when operating under the condition of first increasing speed to working speed and then increasing pressure.When conditions permit,the floating performance should be analyzed before driving,and then the order to appaly the operating conditions should be selected