A novel resonator cavity microwave sensor for high-temperature blade tip clearance measurement

The blade tip clearance is the key to efficiency and safety of rotating engines with accurate and real-time measurement. Existing microwave sensors can only withstand 900 °C. This paper introduces a novel resonant cavity sensor, withstanding up to 1300 °C. Using a high-impedance compensation method, the high-temperature section for the sensor has been designed. The sensor’s structure is designed based on the principle of electromagnetic field superposition and optimized by electromagnetic field simulation. A phase compensation method of transmission path based on dual-frequency technology has been proposed. Prototypes are developed and the performance tests are completed. Results show a monotonic relationship between the phase difference measurements and actual blade tip clearance values. The novel sensor is suitable for dynamic measurement of blade tip clearance. Additionally, the sensor operates reliably at high temperatures up to 1300 °C. The measurement deviation of blade tip clearance between high-temperature and room-temperature is always within ±10 %.