[119] Localisation of the blade excitation using shaft vibration signal measurement
V Vasicek, J Liska, J Jakl and J Strnad
University of West Bohemia in Pilsen, Czech Republic
Condition monitoring is the process of signal measuring and processing to detect an early change in the system. In turbomachinery, blade state monitoring is an important task of this kind. It is important, especially in terms of the last stages of the low-pressure turbine. In general, the stress acting on blades here is the highest. In recent years, the authors of this paper developed a new approach to low-pressure steam turbine blade monitoring using the standard instrumentation by the shaft vibration sensors. This approach is described in this paper together with examples of experimental data evaluation. Apart from the amplitudes and frequencies of the blade vibration, it was also shown that the phase spectrum can be used for the localisation of blade excitation. This approach is described in this paper in detail. The derived formulae describing the principle were validated by measurements using the experimental rotor stand in the laboratory.
