Research Of Unbalance Force Identification Method For Rotor System With Multiple Disks

Vibration is the important factor influencing the safe and reliable operation of rotating machinery, such as turbo generator unit. Rotor unbalance is the fault that usually happens in rotating machinery. Balance rotor accurately and effectively is important.High and medium pressure rotor finite element model of turbo generator unit was set up. Shaft bend under external force action was calculated. It is shown that shaft bend will be caused if the balance plane is not coincide with the unbalance plane. External unbalance force caused by shaft bow will act on the rotor and the balance state is destroyed. It will cause rotor unstable vibration. It explains the unstable vibration occurring on many high pressure rotor of turbine.The method to identify unbalance force of multiple disks was put forward. It reduces the unstable vibration. It identifies the unbalance force of each disk. It considers the unbalance force and its angle in the rotating coordinate system is constant. The unbalance force may be measured from the change of shaft section moment which rotates with the shaft synchronously. Change of shaft moment can be measured using strain gauge.Test was done on rotor-bearing rig to verify the accuracy and the reliability of the method. Test project was set up. A set of test were done including unbalance magnitude identification, unbalance angle identification and unbalance distribution identification of rotor system with single disk and multiple disks at different rotating speeds. The identification method was verified preliminarily.