Bifurcation and hunting phenomena of rotating speed in a flexible rotor system caused by whirling motion

This paper presents the discussion of experimental results and numerical simulation of nonlinear phenomena in a flexible rotor system under mechanical resonance. The whirling motion of the first flexural mode of the rotor causes the hunting of its rotating speed. Hysteretic jump phenomena exist between the charge and the discharge of the rotation. It is shown that the quasi-periodicity of the whirling motion is closely related to the hunting of the rotating speed. When the rotor is coupled to a generator, a continuous change of output power cannot be achieved under mechanical resonance. These results show the necessity to stabilize the whirling motion and the hunting, for example in a flywheel energy storage system.