Non-contact measurement of stationary characteristics of shrouded steam turbine blades under rotation

Abstract

The paper deals with new non-contact measurement methods of stationary deflections of steam turbines blades under rotation. These methods are based on the properties of highly sensitive and accurate magnetoresistive sensors developed by the authors. Biaxial sensors enable measurements not only in the circumferential, but also in the axial direction, which is essential for the shrouded blades. 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.