Workable mode design and experimental verification of aero-engine low-pressure rotor system

A dynamic model of aero-engine low-pressure flexible rotor with elastic supports and dampers was established，the modal and critical speed responses were calculated.Under the condition of considering the constraint of critical speed and the constraint of “critical following”phenomenon，the influence factors of modal imbalance，the proportion of spring-supported strain energy，and the stability of the sleeve-tooth connection structure were synthesized to construct a tolerance evaluation function，and a “workable mode” optimization design method for the low-pressure rotor system was established.The low-pressure rotor experimental system was designed and established，and the reliability of the design method was verified from the modal test experiment，damper damping experiment and long-term “resonance” experiment.The study results indicated that the maximum error between the calculated critical speed and the actual measured critical speed did not exceed 3.86%.The maximum damping ratio of the damper at the first and second critical speeds can reach 45.6%.The experimental rotor system completed 412.5 s and 429.8 s “resonance” experiment at the first and second critical speeds，and the rotor system of each channel vibration peak kept stable within 100 μm during the resonance process without sub-harmonic generation.The results show that the established optimization design method of “capacity mode” for aero-engine low-pressure rotor system is feasible.