某型航空发动机振动值波动故障诊断和排除

In order to tackle the steady vibration fluctuation issues in engine tests, the thorough frequency-domain analysis and time-domain analysis are performed. It is found that the vibration fluctuation is induced by the beat vibration between the low-pressure (LP) bi-frequency and high-pressure (HP) fundamental frequency. The vibration response resulted from the beat vibration is calculated. The dual-rotor dynamic model of the aeroengine is established and the numerical simulation is carried out. Results show that the close in the frequencies of two exciting force would generate beat vibration and lead to vibration fluctuation, which is consistent with the experimental results. Combining the engine structure and working characteristics, the mechanism of beat vibration resulting from the LP bio-frequency and HP fundamental frequency coupling is analyzed. The beat vibration elimination method is proposed and validated by the experiments. An effective approach is to adjust the shaft speed difference to accommodate the shaft speed ratio and eliminate the beat vibration.