a broken turbine bucket (blade) will be IMMEDIATELY seen as a journal bearing vibration increase. for any turbine stage, with a possible exception of the last stage, there will be resulting colaterail damage to other buckets.
FORCING a turbine back into service with a minor broken bucket will result in harmontics and cause breakage of other buckets with few hours of operation thus being major damage
You should provide more information on the type of turbine you are interested in. We have overhauled a multi-stage steam turbine and found a broken blade in the last stage. We believe that this break had occurred months or even years ago. There was no clear evidence in the vibration. But, it was a very small piece broken off relative to the size of the blade and the weight of the rotor.
@JJpelim i am interested about steam turbine blades. In your case breakage is very little but if 2 or 3 blades get broken then i think vibration is only phenomenon from where we can get information
You still have not provided information on the turbine involved. For the turbine that I referenced, the loss of two blades on any stage would certainly result in the turbine tripping off on high vibration. If the turbine did not trip off for some reason, I would expect a bearing failure. Are you proposing placing a turbine back into service with missing blades?
Keep in mind that vibration is a vector, consisting of an amplitude and a direction. If a small portion of a blade is lost and if the location of that damaged blade is 180 degrees from the vibration vector before the loss, there is a change in the vibration vector. However, the amplitude portion of the vibration vector may not increase, or could decrease, since the new vector is 180 degrees away from the original vector.
We observed the same phenomenon of cracks in last stage of reaction turbine. Plants is tripped on high vibration if there occurs turbine dynamic imbalance due to breakage of blades. Vibration of journal bearings across turbine rotor is mirror for turbine behaviour.
