Microwave autodyne vibrosensor in aeroengine diagnostics

The sensor is designed for in-flight aeroengine turbine blade vibration monitoring. The sensor operation and construction are similar to liquid rocket engine flame parameters sensors, which were presented on 20´th European Frequency and Time Forum. Three dimensional (3D) electromagnetic (EM) field structure and its fluctuation depending on regular, vibrating and damaged blade travel states have been researched in quasi-static approximation. Probing frequency varied from 4 to 40 GHz, and range from 28 to 37 GHz was accepted as preferable. Field structure impact on antenna current flow, its vector admittance, and reflectivity have been found out. Furthermore, computational EM simulation by FEKO software tool was applied. Then autodyne frequency response form was found out. During regular turbine rotation radio frequency (RF) spectrum is sampled. Sampling rate F is a multiplication of rotation frequency (hundreds of hertz) to number of blades (approximately one hundred hertz). Estimated samples amplitudes are stipulated by response form and modulated by vibration process.