Study on the influence of combined unbalanced phase difference on rotor vibration response and high-speed dynamic balancing

Aiming at the problem of excessive vibration caused by the coupling of compressor unbalance and turbine unbalance of the aero-engine gas generator rotor, the vibration response law of the rotor and its influence on high-speed dynamic balancing is studied from the perspective of combined unbalanced phase difference. In this paper, the typical structure of the gas generator rotor system in a turboshaft engine is simplified, and the dynamical model of the rotor system is established by using the finite element method and the lumped mass method. Based on the dynamical model, the combined unbalanced phase difference is introduced to reveal the influence of the combined unbalanced phase difference on the vibration response of the rotor system. The influence coefficient matrix is constructed by the relationship between the unbalanced excitation and the vibration response of the rotor system. The least squares influence coefficient method based on the Nutcracker optimization algorithm is proposed to study the influence of combined unbalanced phase difference on high-speed dynamic balancing. The corresponding test was carried out based on the developed rotor system simulation test rig with a similar structure and dynamics to the gas generator rotor. The results show that the influence of combined unbalanced phase difference on the vibration response amplitude presents a cosine waveform. The peak and trough positions of the cosine waveform depend on the dominant vibration mode at the measured speed. The combined unbalanced phase difference is 180°, and the high-speed rotor’s vibration reduction rate is highest when it passes the critical speed after dynamic balance. The work of this paper provides a theoretical basis for the vibration control of the high-speed dynamic balancing of the rotor and provides important support for the actual needs of the project.