支承方式对变循环发动机转子临界转速的影响

Influence of Bearing Method on Critical Rotor Speed of Variable Cycle Engine

分析某双涵道变循环发动机转子系统结构特点,建立转子-支承系统三维有限元模型,计算、分析转子支承方式的改变对转子临界转速的影响。结果表明:以低压转子为主激励,转速在20000 r/min内,4支点支承比5支点支承临界转速多一阶,其中第一、三阶临界转速降低,第二阶升高,第四阶基本不变。5支点方式能有效地减少柔性低压转子弯曲振动模态出现,但是会增加低压风扇盘的上下偏摆振动模态,较易发生风扇叶片与机匣的碰磨。4支点方式结构更简单,但是转子系统在高转速时需要多经过一阶临界转速,会增加转子及整机的振动。

The structural characteristics of the rotor system of a double culvert variable cycle engine are analyzed,the three-dimensional finite element model of rotor-bearing system is established,and the influence of the change of rotor bearing method on the critical speed of rotor is calculated and analyzed.The results show that the four-bearing method,with the low-pressure rotor as the main excitation,has one more critical speed than the five-bearing method within 20000 r/min.,in which the first and third critical speeds decrease,the second increases,and the fourth basically remains unchanged.The five-bearing method can effectively reduce the occurrence of bending vibration modes of the flexible low-pressure rotor,but will increase the up and down pendulum vibration modes of the low-pressure fan disk,which is more prone to collision and friction between the fan blade and the casing.The structure of the four-bearing method is simpler,but the rotor system needs to pass through one more critical speed at high speed,which will increase the vibration of the rotor and the whole engine.