Abstract
Blade tip timing (BTT) technology is the most effective means for real-time monitoring of blade vibration. Accurately extracting the time of blade tip reaching the sensors is the key to ensure the accuracy of the BTT system. The tip clearance changes due to various complex forces during high-speed rotation. The traditional BTT signal extraction method does not consider the influence of tip clearance change on timing accuracy and introduces large timing errors. To solve this problem, a quadratic curve fitting timing method was proposed. In addition, based on the measurement principle of the eddy current sensors, the relationship among the output voltage of the eddy current sensor, tip clearance, and the blade cutting magnetic line angle was calibrated. A multisensor vibration parameter identification algorithm based on arbitrary angular distribution was introduced. Finally, the experiments were conducted to prove the effectiveness of the proposed method. The results show that in the range of 0.4 to 1.05 mm tip clearance change, the maximum absolute error of the timing values calculated by the proposed method is 26.0359 us, which is much lower than the calculated error of 203.7459 us when using the traditional timing method. When the tip clearance changed, the constant speed synchronous vibration parameters of No. 0 blade were identified. The average value of the vibration amplitude is 1.0881 mm. Compared with the identification results without changing tip clearance, the average value error of the vibration amplitude is 0.0017 mm. It is proved that within the blade tip clearance variation of 0.4 to 0.9 mm, the timing values obtained by the proposed timing method can accurately identify the vibration parameters of the blade.
Highlights
Blades are considered to be the core component of aeroengine compressor
Erefore, accurate measurement of the blade tip timing time is the key of the Blade tip timing (BTT) technology
In the heavily polluted environment, due to the surface pollution of the probe, the measurement accuracy of the optical method decreases. e measurement accuracy of the capacitance method is affected by insulation, stray capacitance, and edge effects. e measurement accuracy of the microwave method is affected by the spatial filtering effect, and the system is expensive
Summary
Blades are considered to be the core component of aeroengine compressor. Real-time monitoring of blade vibration state can effectively prevent blade failures [1]. E constant ratio timing identification method [10] uses half of the height of the rising edge of the pulse signal as the blade arrival time This method has high signal processing difficulty and is still affected by the change of the blade tip clearance. According to the collected pulse signal sampling points, based on the eddy current sensor, a method for accurately extracting the blade timing time when the blade tip clearance changes is proposed.
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