关键词: 叶尖定时测量, 趋势项拟合, 自适应, 相关系数

Abstract: Blade tip timing measurement was a key measurement technology in aero-engine blade vibration monitoring systems. As an important part of timing signal preprocessing, the trend term fitting was the basis and premise of high-precision parameter identification of the blade vibrations. Under the continuous variable operating conditions of aero-engines, the current trend item fitting method could not adaptively adjust the width of the fitting windows, resulting in the poor quality of eliminating the trend items and seriously affecting the subsequent blade vibration analyses. Aiming at the problems of timing signal trend item fitting under continuing variable operating conditions, this paper used correlation coefficient as the evaluation of trend item fitting quality, and proposed a trend item fitting method with the window widths of adaptive adjustment. The tip-timing test data of an aero-engine high-pressure compressor was used for verification. The results show that the method may ensure the optimal fitting quality of the trend item due to adaptively adjusting the widths of the window. Under the premise of removing the trend item, the original vibration information may be completely retained, which is of great significance to achieve high-precision parameter identification of the blade vibrations.

Key words: blade tip timing measurement, trend term fitting, adaptive, correlation coefficient