基于频谱的篦齿轴向窜动与叶尖间隙测量方法

Measuring method of axial movement and tip clearance of labyrinth seals based on the amplitude spectrum

航空发动机低压涡轮带冠叶片篦齿和机匣之间的叶尖间隙参数以及篦齿轴向窜动参数的在线高精度测量是保证涡轮发动机安全运作和气动效率的关键。传统的电容式叶尖间隙测量系统对噪声敏感度大,且不能对篦齿的轴向窜动参数同时进行测量。因此研制了一种“人”字形电容传感器,提出了一种基于频谱的篦齿叶尖间隙参数和轴向窜动参数的提取方法。建立了“人”字形电容传感器测量模型。仿真分析了测量信号的幅度谱特征并提出了一种最优谱线选择方法。提出了基于转速和信号特征频率估计的自适应频域滤波,信号整周期等角度采样,幅度谱估计以及二元多项式曲面拟合相融合的信号处理方法,实现了叶尖间隙参数和轴向窜动参数的动态测量。在实验室环境下搭建了篦齿叶尖间隙参数和轴向窜动参数测试实验平台,完成了标定和测量实验。实验结果显示,篦齿盘工作在1900 r/min以下时,测量系统在0.5~1.5 mm叶尖间隙及±1 mm轴向窜动范围内,叶尖间隙测量精度达18μm,轴向窜动测量精度达30μm。

Online high-precision measurement of tip clearance parameters between the labyrinth seals and the casing and axial movement parameters of labyrinth seals are the key to ensuring the safe operation and aerodynamic efficiency of turbine engines.The traditional capacitive tip clearance measurement system is sensitive to noise and cannot measure the axial movement parameters of labyrinth seals at the same time.Therefore,a“herringbone”-shaped capacitive sensor is designed,and a method for extracting the parameters of labyrinth seals’tip clearance and axial movement parameters based on spectrum estimation is proposed.The measurement model of the herringbone capacitance sensor is established.The amplitude spectrum characteristics of the measured signal are simulated and analyzed,and the optimal spectrum line is determined.A signal processing method of adaptive frequency domain filtering based on estimation of rotation speed and signal characteristic frequency,full-period and uniform angle sampling,amplitude spectrum estimation,and binary polynomial surface fitting is proposed to realize the dynamic measurement of blade tip clearance parameters and axial movement parameters.The experimental platform for testing tip clearance parameters and axial movement parameters of a labyrinth seal is established in the laboratory environment.The calibration and measurement experiments are completed.Experimental results show that when labyrinth seals work below 1900 r/min,the measurement accuracy of blade tip clearance and axial movement is 18μm and 30μm within the measurement range of 0.5~1.5 mm blade tip clearance and±1 mm axial movement.