Design of Resonant Cavity Based Sensor for High-Temperature Blade Tip Clearance Measurement

Online and accurate measurement of blade tip clearance is the key to improve turbine engine's efficiency and ensure its safety. Development of microwave sensor with high temperature resistance will impel the blade tip clearance measurement system to engineering application. A novel sensor based on resonant cavity structure for high-temperature blade tip clearance measurement is presented in this paper, using the phase difference ranging principle. A compensation method for impedance discontinuity is proposed by axial dislocation of stepped transition. The cable cooling transition section is designed, whose length is determined by electromagnetic and thermal simulation, so the proposed sensor can withstand high temperature of 1573.15 K The measured phase changes monotonously with the blade tip clearance, so accurate measurement of blade tip clearance can be realized using the calibration curve.