Identifying rotating blades vibration from the shaft torsional vibration signals

This paper presents results from an experimental study on the identification of rotating blades vibration from the shaft torsional vibration signals. Test rigs that contain 12 blades bladed disk with shaft equipped with lateral and torsional vibration measurement is designed and manufactured. Startup and steady state operational conditions are experimentally simulated. The results from two blades strain gages and the rotor lateral and torsional vibration measurements showed that the blades vibration signatures can be identified effectively from the shaft torsional vibration signals. More sensitive shaft torsional vibration signals to blades vibration are shown for closer torsional vibration measurement from the bladed disk. Moreover, the shaft torsional vibration signals can be more representative of blades vibration if the IX rotor vibration due to unbalance is filtered out.