High-precision dynamic axial clearance measurement method based on an all-fiber heterodyne microwave-AMCW with an...

Area of Science:

• Mechanical Engineering
• Optical Metrology
• Sensor Technology

Background:

• Accurate measurement of rotor-stator axial clearance is vital for rotating machinery safety and efficiency.
• Environmental factors like vibration and temperature challenge high-precision dynamic clearance measurements.
• Existing methods often lack the required precision, bandwidth, or measurement range for demanding applications.

Purpose of the Study:

• To develop a high-precision, wide-bandwidth, and large-range axial clearance measurement method for rotating machinery.
• To mitigate environmental interference in dynamic clearance measurements.
• To introduce a novel bandwidth testing method for system evaluation.

Main Methods:

• An all-fiber heterodyne microwave amplitude-modulated continuous wave (AMCW) system was developed.
• A compact dual-core fiber sensor probe and a heterodyne all-fiber optical path were designed.
• An all-phase tracking algorithm was implemented to enhance dynamic precision and bandwidth, alongside a time-division multiplexing bandwidth test.

Main Results:

• The system demonstrated excellent resistance to environmental interference.
• Achieved a measurement range of up to 24.5 mm with static precision better than 4.5µm.
• Dynamic experiments confirmed precision better than 5.3µm at 100kHz bandwidth, reducing dynamic error by over 74% compared to other algorithms.

Conclusions:

• The proposed all-fiber heterodyne microwave-AMCW system with an all-phase tracking algorithm offers a robust solution for high-precision dynamic axial clearance measurement.
• The system's performance, validated by simulations and experiments, meets the stringent requirements for critical rotating machinery.
• This method significantly improves upon existing techniques, offering enhanced accuracy and a wider operational range for industrial applications.