Eddy Current Sensor System for Blade Tip Clearance Measurement Based on a Speed Adjustment Model.

Area of Science:

• Aerospace Engineering
• Mechanical Engineering
• Sensor Technology

Background:

• Blade tip clearance (BTC) and active clearance control (ACC) are vital for aero-engine efficiency, reliability, and maintenance.
• Eddy current sensors (ECS) are robust for BTC measurement, but current methods neglect the impact of BTC on response time and signal decay with speed.
• Addressing these limitations is crucial for advanced aero-engine health monitoring.

Purpose of the Study:

• To propose and validate a novel speed adjustment model (SAM) for accurate BTC measurement using ECS.
• To quantitatively establish the relationships between ECS measurement loop response time, BTC, and signal output with engine speed.
• To enhance the accuracy and operational speed range of BTC measurement in aero-engines.

Main Methods:

• Developed a speed adjustment model (SAM) trained via nonlinear regression on experimental dynamic data.
• Employed the Levenberg-Marquardt (LM) algorithm to estimate SAM characteristic parameters.
• Proposed a blade tip clearance measurement method (BTCMM) integrating SAM and a geometric constraint equation for accuracy assessment.

Main Results:

• Established quantitative relationships between ECS response time, BTC, and signal output versus engine speed.
• Validated the proposed BTCMM through real-time experiments on a micro turbojet engine.
• Demonstrated significant improvements in BTC measurement accuracy and expanded the applicable engine speed range.

Conclusions:

• The proposed SAM effectively addresses key limitations in ECS-based BTC measurement.
• The BTCMM offers a reliable and accurate method for real-time BTC monitoring in aero-engines.
• This advancement contributes to improved aero-engine health monitoring and performance optimization.