Gas turbine generator sets are widely used in IGCC system, gas-steam combine cycle, distributed energy system et al. for its advantages of low pollution, high efficiency, quick start and stop. The structure of gas turbine rotor can be divided into integral rotor and rod-fastened rotor. Experimental study shows that the vibration signal, especially the displacement signal, of the rod-fastened rotor will increase/decrease greatly in a small interval of rotating speed. The reason for this phenomenon is the unique structure of the rod-fastened rotor, namely the interfaces between discs. In this paper, based on the Lagrange equation, the equation of motion of a rod-fastened rotor-bearing system considering the damping of the contact interface is established. The bistable behaviour and hysteretic cycle, also called the jumping phenomenon in engineering, are revealed. In addition, a test bench of the rod-fastened rotor-bearing system is built. The bistable behaviour and hysteretic cycle are experimentally proven, and the effect of the eccentric distance of the rotor on the bistable behaviour is experimentally explored.

Rod fastened rotor is widely used in gas turbine and aero engine. Normally, rod fastened rotor is supported by sliding bearings, but in engineering, improper bearing clearance would lead to severe vibration of the system. Combined support, i.e., squirrel cage-squeeze film damper, could decrease the stiffness and increase the damping of the system. It is usually used to reduce the vibration of integral rotor. In this paper, the dynamic behaviour of rod fastened rotor-combined support system is explored. Based on the Lagrange equation, the equation of motion of rod fastened rotor-squirrel cage-squeeze film damper system is derived. The bistable behaviour and non-synchronous response are disclosed. Besides, a rod fastened rotor-squirrel cage-squeeze film damper bench is built, the bistable behaviour and non-synchronous response are proven experimentally, and the effect of the pressure of the oil film on the nonlinear dynamic behaviour is experimentally explored.