Online condition monitoring of axial-flow turbomachinery blades using rotor-axial Eulerian laser Doppler vibrometry

The ability to monitor the vibration of blades online is of great importance to the structural health of turbomachinery. This paper focuses on the fixed reference frame or Eulerian implementation of laser Doppler vibrometry to perform this function. The way in which this measurement technique works is studied analytically and then a numerical simulation approach is proposed. Through experimental testing and finite element modeling, it is shown that this measurement approach is in principle viable for online blade condition monitoring when phase angles at reference frequencies are monitored, using non-harmonic Fourier analysis.