High-accuracy experimental analysis and correction of blade tip timing measurement error
Accurate measurement of blade tip displacement is the basis for the application of blade tip timing(BTT)technology to the vibrational mode reconstruction and real-time condition monitoring of rotating blades.A high-precision BTT calibration device based on a laser displacement sensor was designed.The time-domain calibration data of the blade tip displacement were directly obtained in the experiment,verifying that the speed fluctuation was one of the main sources of the measurement error of the blade tip displacement.On this basis,a local fifth-order fitting rotation speed fluctuation correction method was proposed to improve the BTT measurement accuracy,and the experimental verification was completed on the calibration device.The experimental results showed that the local fifth-order fitting method can effectively improve the BTT measurement accuracy under different working conditions.The measurement error can be reduced by up to 90％under the condition of non-linear increase in rotational speed,and the measurement error can be reduced by 38％to 63％under the condition of constant speed.The algorithm was applied to the experimental data of a single-stage axial flow compressor,and the corrected error was as high as 0.4 mm,which effectively reduced the uncertainty of the real-time measurement of blade tip displacement by BTT technology.
blade tip timingblade tip displacementspeed fluctuationcalibration deviceerror analysis
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