Comparison between long and short blade vibration using shaft instantaneous angular speed in rotating machine

The blade failure normally occurs as a result of blade cracking due to unforeseen operating conditions and variable loads. Therefore, the early detection of damage in the blades is critical to reduce machine down time, maintenance costs and to maintain overall safety. Earlier studies indicate that the shaft instantaneous angular speed (IAS) representing the shaft torsional vibration is a good approach for the blade vibration. Hence, the shaft IAS is extracted from the measured encoder data during machine run-up to understand the blade vibration. A number of experiments on an experimental rig with a bladed disk were conducted using 2 types of blades (long and short blades) with healthy but mistuned blades and with different faults simulation in the blades. The paper presents the experimental setup, simulation of blade faults, experiments conducted, observations and comparison of results between the long and short blades with and without faults