Operational Measurement of Stationary Characteristics and Positions of Shrouded Steam Turbine Blades

This paper deals with new noncontact measurement methods of stationary deflections of steam turbine blades under rotation. These methods are based on the properties of the magnetoresistive sensors developed by us, which are highly sensitive, accurate, and advantageous compared with other types of electromagnetic sensors. Biaxial sensors enable measurements not only in the circumferential but also in the axial direction, which is essential for the shrouded blades. The proposed methods were used for measurements of axial displacements at the blade root of the low-pressure turbine stages. Methods for measuring axial displacements of the shrouded blades at the tip are also presented. The description of the methods is completed by the signal records obtained by measurements at a real steam turbine.