Experimental investigation on dynamical response of an overhung rotor due to sudden unbalance

Blade loss is a typical extreme load in the turbo machinery, which can cause intense vibration in rotor and huge loads in supporting system due to the sudden unbalance applied on the disk. An overhung rotor-support system is built to study the dynamic characteristics of rotor and support experimental system under the sudden unbalance excitation. The responses due to a mass loss are tested respectively both in subcritical state and in supercritical state, further the orbits of the rotor and load transmitting process on the stator are obtained and investigated. Moreover, the impact effect of response achieved by a mechanical model is presented to compare with the test result. The results show that sudden unbalance can induce an impact effect on the rotor system with response containing rotational speed frequency and natural frequency in frequency domain. The impact effect is more evident for flexible rotor than the rigid rotor, and the vibration response exhibits local effect. As a consequence the paper provides a reference and basis for the dynamical design and analysis for flexible overhung rotor system suffering sudden unbalance.