基于叶端定时的转子叶片动应变重构不确定性量化

Uncertainty quantification of rotor blade dynamic strain reconstruction based on blade tip timing

基于叶片非接触式动应变重构理论,开展动应变重构不确定性量化方法研究。基于方差合成定理建立重构叶片动应变不确定性量化分析模型;以模拟转子叶片为研究对象,开展旋转叶片叶端定时试验,利用周向傅里叶算法获取不同叶端定时传感器布局下的测点振幅,通过最大熵方法拟合振幅分布概率密度函数,确定叶端定时测振的不确定性参数;结合Kriging代理模型和试验共振频率数据对叶片有限元模型进行修正,获取关键测点位移-应变转换因子,并获取考虑共振转速以及测点位置不确定性的转换因子不确定性参数;获取重构动应变的均值、标准不确定度和包含区间,与应变片测量数据作对比。结果表明,除5号叶片A测点外,测量动应变均位于重构动应变的95%置信度下的包含区间内,且所有叶片的应变片测点动应变重构误差不超过15%。

Based on the theory of blade non-contact dynamic strain reconstruction,research on the uncertainty quantification method of dynamic strain reconstruction was carried out.According to the variance composition theorem,a model of the blade reconstructed dynamic strain uncertainty for quantitative analysis was established.A simulated rotor blade was used as the research object,and the rotation experiment was carried out.The circumferential Fourier Fitting was used to obtain the amplitude of measuring point under different blade tip timing sensor layouts,and the maximum entropy method was adopted to fit the probability density function of the amplitude distribution,which could be used to determine the uncertainty parameters of the blade-tip-timing vibration measurement.The finite element model of the blade was modified by combining the Kriging proxy model and the resonant frequency of the test.The displacement-strain conversion factors of the key measuring points were obtained,and the uncertainty parameters of the conversion factor considering the uncertainty of the resonance speed and measuring point position were obtained.The mean value,standard uncertainty and inclusion interval of the reconstructed dynamic strain were obtained and compared with the measured data of the strain gauge.Results showed that except for the measuring point A of No.5 blade,the measured dynamic strains were all within the 95% confidence interval of the reconstructed dynamic strain,and the dynamic strain reconstruction error of the strain gauges of all blades didn’t exceed 15%.