Estimation of static deflection under operational conditions for blade health monitoring

Reliability and availability of gas turbines are critical to industry as they are used in a variety of applications. It is important to determine the health of these complex systems in near-real time and detect failures as early as possible. Cracks in compressor blades, used in gas turbines, if not detected early, could lead to catastrophic failures that would result in increased costs and extended outages. These cracks tend to induce changes in the static deflection of the blade. By tracking the changes in static deflection, it is possible to determine whether a blade is cracked or not. However, the static deflection of the blade, under field conditions, is also affected by operational parameters of the gas turbine. Therefore, estimating static deflection under field conditions and isolating the effects of crack from that of operational parameters is a significant task. This paper describes an algorithm for the estimation of static deflection under field conditions. It discusses some of the challenges involved and possible solutions for mitigating them. This algorithm can be used in conjunction with a crack propagation model to determine crack size in real-time.