Influence of diagnostic signal sampling frequency on rotor blade technical condition images determined from phase shift difference

In the article, research results of rotor blades technical condition monitoring basing on special model phi T12T01 during operation are presented for various sampling frequencies. Method based on phi T12T01 model which is a difference of diagnostic signal y(t) phase shift resulting from blade operation and signal x(t) of its environment during blade tip approach to the sensor and its recession from the sensor. The assumed diagnostic model indirectly takes current blade environment x(t) into consideration without necessity of measurement. Three out of 28 blades placed on first level of turbine engine compressor were analyzed. Research were undertaken in teta 1 time for sampling frequencies of 500 kHz and 2 MHz. Results obtained for phi T12T01 model present the same technical condition (image) of blades. The aim of this study is to present application of diagnostic model to rotor machine blades diagnostics during operation without necessity of measuring the environment signal as well as to prove that the method is correct for both smaller and greater sampling frequencies. Importance of this is a result of a fact, that sampling frequency increase requires more expensive, specialist equipment.