Fast algorithm of single frequency-swept interferometry for the dynamic axial clearance measurement of high-speed rotating machinery

Abstract

Utilizing the periodicity of the rotating machinery, dynamic clearance measurement can be achieved with a single swept light source without any additional auxiliary devices, which has the advantages of simplicity and reliability. However, there is a shortcoming that previous algorithm is not fast enough to achieve real-time measurement when the machinery rotates at high speed. Aiming at this shortcoming, utilizing the correlation between mimic signal and measurement signal, combined with information for multiple periods, the fast algorithms and dynamic clearance corrected model were proposed. And the relationship between demodulation speed and cycle numbers was also discussed. Simulation was carried out to discuss the influence of different algorithm on the demodulation speed and accuracy. A test system was set up in the simulated environment for clearance measurement, and the results show that, the demodulation time of the proposed algorithm costs decreased dramatically, the speed has increased by about ten times, and the dynamic clearance measurement error is less than 2 µm.