14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Ensuring the reliability of the steam turbine is fundamental task for a proper operation. Monitoring systems are traditionally used for this purpose. Early detection of initial mechanical change can avoid time and financial losses. The last stage blades of low-pressure turbine can be considered as the critical part in a steam turbine operation. The interaction between steam flow and the blisk causes the mechanical stress acting on the blades. Traditional methods used for monitoring blade dynamic behaviour are contact method represented by strain gauges measurement and non-contact method – blade tip timing. However the installation and operation of such monitoring systems is quite expensive. Rising demand for low-cost monitoring systems led into developing new approach which is presented in this paper. It is based on the use of the standard measurement – relative rotor vibration signal. Using the standard measurement makes this approach potentially interesting for the turbine operators compared to the methods traditionally used. This paper illustrates how this principle can be used in blade state monitoring and early identification of the mechanical change in blade structure. The experimental results measured on an experimental rotor test rig are also presented in the paper to support presented approach.