转子系统的动力学“临界跟随”特征及其试验验证

In order to deeply investigate the mechanism of “critical following speed”, a cantilever rotor dynamic model was established. The dynamic characteristics of the rotor system under “critical following speed” were analyzed. The cantilever rotor experimental system was designed and established, and experimental verification was finished on the overspeed test bench. The analysis results showed that from a certain rotational speed, when the diameter rotational inertia was equal to polar rotational inertia, the vibration pendulum angle response of the disk increased with the increasing rotational speed. The characteristics of the mode shape under “critical following speed” lied in that the disk (diameter rotational inertia was equal to polar rotational inertia) was located at the node of mode shape. The vibration displacement of the disk center was 0, but the pendulum angle of the disk was not 0 and increased with the increasing rotational speed, and the phase angle was kept constant. If the rotor was not a single-disk structure, the diameter rotational inertia and polar rotational inertia of the component should be calculated to determine whether the “critical following speed” phenomenon occurred. Considering the mass of the rotating shaft, when the disk satisfied the condition which diameter rotational inertia was equal to polar rotational inertia, the phenomenon of “critical following speed” did not occur, and the natural frequency line could be close to the speed line within a wide range, which would widen the “resonance vibration” region. “critical following speed” made vibration extremely sensitive to unbalanced load, which should be avoided in rotor dynamics design.