THE OPERATION ALGORITHMS OF THE SYSTEMS FOR MEASURING OF IRREGULAR SHAPED BLADES TIPS' RADIAL AND AXIAL DISPLACEMENTS 

Belopukhov Valentin Nikolaevich, candidate of technical sciences, researcher, Institute of Control Complex Systems of Russian Academy of Sciences (61 Sadovaya street, Samara, Russia), bvnsam@mail.ru
Borovik Sergey Yur'evich, doctor of technical sciences, leading researcher, Institute of Control Complex Systems of Russian Academy of Sciences (61 Sadovaya street, Samara, Russia), borovik@iccs.ru 
Kuteynikova Marina Mikhaylovna, researcher, Institute of Control Complex Systems  of Russian Academy of Sciences (61 Sadovaya street, Samara, Russia), m.kuteynikova@mail.ru

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Background. The paper discusses the problem of measuring of radial an axial displacements of blades tips’ used in turbines of modern gas-turbine engines. The blades have irregular shape and enhanced surface curvature. The peculiarity of measuring methods based on use of distributed clusters of single-coil eddy-current sensors with sensitive elements made as a conductor strip is considered. The aim of the article is to present the main operation algorithms of the systems that realize these methods.
Materials and methods. The main methods are: the numerical analysis, approximation methods and the theory of algorithms.
Results. The operation algorithms of the systems that realize the methods of measuring of blades tips’ with irregular shape radial an axial displacements are proposed. The algorithms include the procedure of preliminary data processing and data compressing as well as a detecting of digital codes that correspond to sensors informative signals when blades tips are passing the sensitive element. 
Conclusions. The algorithm of preliminary data processing provides input data compressing before their transmission on upper level in PC. That increases the system operation speed. The algorithms of a detecting of digital codes decreases a digitizing error due to the code envelope reconstruction with the help of interpolation processing on the base of Chebyshev polynomial or parabolic approximation of code samples with further extreme detection.

single-coil eddy-current sensor, radial and axial displacements, turbine, complex shaped blades, measuring system, operation algorithms