航空发动机转子篦齿封严诱导的气流激振力分析

Analysis on Airflow Induced Forces of Aero-Engine

关键词:  鼓筒篦齿密封  偏心  进动频率比  表面静压  刚度系数  阻尼系数

Key words:  Drum with labyrinth seals  Eccentric  Precession frequency ratio  Surface pressure  Stiffness coefficient  Damping coefficient

摘要:

为了解航空发动机直通型篦齿封严诱导的鼓筒表面气流激振状态以及不同参数对其的影响，对航空发动机直通型篦齿封严诱导的气流激振力进行研究，对转子无偏心和有偏心两种情况进行数值仿真计算。定性分析不同偏心量、不同进动频率比对气动力的影响；利用数值计算结果确定篦齿封严诱发的气流激振力大小；根据不同进动频率下的静压分布可以进一步导出气动阻尼、气动刚度参数，得到篦齿封严转子的气动载荷边界条件。结果表明:无偏心时篦齿封严腔内的流动非定常性不明显，气流激振对篦齿封严转子的影响可基本忽略；转子存在偏心时流体腔内流动具有非定常特征，气流激振力将驱动转子进动运动；不同偏心量的静压值比无偏心量时最大可增长7%，静压幅值波动值随进动频率比增大而增大，最大可比进动频率比为0时增长达84%，对转子的动力学稳定性有一定影响。

Abstract:

In order to understand the air vibration status on the drum surface induced by pass-through type grate tooth seal in the aircraft engine and the influence of different parameters，the air vibration force induced by the straight-through type grate tooth seal was studied，and the numerical simulation on two situations: with eccentricity and without eccentricity was carried out. The effects of different eccentricities，different precession frequency ratios on the aerodynamic force are analyzed qualitatively. The results of numerical calculation are used to determine the air vibration force induced by pass-through type grate tooth seal. According to the static pressure distribution under different precession frequencies，aerodynamic damping parameters and aerodynamic stiffness parameters can be derived，which determines aerodynamic load boundary conditions of the rotor with grate tooth seals. Results indicate that without eccentricity the flow unsteadiness in the grate tooth seal cavity is not obvious，so the influence of airflow vibration to the drum can be ignored. While with different eccentricities，there are obvious flow unsteadiness characteristics in the cavity，and the air vibration force can drive the rotor precession movement. Static pressure values with different eccentricities can be 7% higher than that without eccentricity，the static pressure fluctuation increases with the precession frequency ratios increasing. It is 84% higher compared with the case with zero precession frequency ratio. This has effects on the stability of rotor dynamics.