Method and System for Measuring Rotor Blade Tip Deflection Using Blade Tip Timing (BTT)

摘要

A method (400) of measuring rotor blade tip deflections of turbomachine rotor blades (R₁, R₂) during operation using Blade Tip Timing (BTT) includes measuring (402), by a proximity sensor (202), a proximity signal caused by a moving rotor blade (R₁, R₂) and determining (412), by a control module (212), a Time-of-Arrival (ToA). The method (400) includes measuring a time that the shaft starts to rotate a measurable angular distance and a time the shaft has completed its rotation of the measurable distance and storing (406) timing data indicative of a plurality of ToA measurements of the rotor blade (R₁, R₂) and the zero crossing times. The method (400) includes determining the shaft Instantaneous Angular Position (IAP) between at least two zero crossing times, which determination comprises expressing the shaft IAP between at least two zero crossing times as a continuous, non-constant IAP mathematical function of time, with unknown function coefficients and calculating the unknown function coefficients of the IAP mathematical function.