航空发动机双转子系统的模态及其表达方法

Here, to solve problems of modal characteristics of dual-rotor system being unable to clearly express, and amplitude-frequency characteristics of main excitation of high-pressure rotor and low-pressure one being not easy to identify in vibration signals, taking a typical engine dual-rotor system as the study object, a finite element model was established to analyze modal characteristics of dual-rotor system. Based on the whirl analysis theory, forward and reverse whirl mode judgment method of double-rotor system was established. The "2-plane 3-dimension" expression method for natural vibration frequencies and critical speeds of double-rotor and the "3-plane 3-dimension" expression method for unbalanced response of double-rotor were established and applied in double-rotor tester. Theoretical analysis and experimental results showed that the "2-plane 3-dimension" expression method of double-rotor natural frequencies and critical speeds can clearly correlate natural frequencies of double-rotor with high-pressure rotor rotating speed and low-pressure rotor one and their common working line; the "3-plane 3-dimension" expression method of double-rotor unbalance response can clearly depict double-rotor vibration together with its rotating speed, rotating direction and rotating speed control law for conveniently understanding and analyzing rotors' vibration characteristics; the study results can play an important supporting role in analyzing and characterizing dynamic characteristics of double-rotor system.