Analysing blade tip timing data

摘要

Blade displacements are detected by a plurality of circumferentially spaced stationary timing probes associated with an assembly of rotating blades mounted on a rotor. The blade displacements correspond to the times at which the blades pass the respective probes. The method including the steps of: (a) identifying a possible resonant vibration event in the assembly of rotating blades; (b) zeroing the blade displacements on the rotations identified with the resonant vibration event to remove invariant blade displacements; (c) fitting modelled blade displacements corresponding to possible blade vibrational deflections at a plurality of frequencies to the zeroed blade displacements; and (d) characterising the resonant vibration event by identifying at each rotation the frequency having modelled blade displacements which correlate best with the zeroed blade displacements. Step (c) includes performing at each individual rotation identified with the resonant vibration event the sub-step of: (c-i) fitting the modelled blade displacements at each frequency to the zeroed blade displacements for a plurality of successive rotations which include that individual rotation. The method does not require a determination of whether a response is synchronous or asynchronous. Blade displacements may be validated by comparing the results of the method with corresponding strain gauge data.