基于激光自混合原理的涡轮叶片转速与叶尖间隙动态同步测量方法

Dynamic synchronous measurement method of turbine blade speed and blade tip clearance based on laser self-mixing principle

针对在高温等恶劣环境下,航空发动机高转速下涡轮叶尖间隙测量稳定性差、易受干扰、精准度低等问题,提出一种基于激光自混合原理的涡轮叶片转速与叶尖间隙动态同步测量方法。首先,提出基于三镜F-P腔模型的自混合干涉模型,并以此为基础构建测速和测距的数学模型;其次着重研究了涡轮叶片转动下动态自混合干涉信号的处理,将采集到的信号依次经过带通滤波以及小波降噪处理,再用FFT进行处理得到频率,由此求得叶尖间隙值;之后分别进行静态和动态激光自混合干涉测距实验进行验证;最后探讨影响动态测量的误差源,并对测量系统以及算法进行优化补偿。实验结果证明,该方法可以有效地提高涡轮叶片转速与叶尖间隙的同步测量的稳定性及精度,测速相对误差为1%,叶尖间隙测量误差为23μm。

The turbine tip clearance measurement has problems of poor stability,easy interference and low accuracy at high speed of aeroengine in harsh environments such as high temperature.To address these issues,a dynamic synchronous measurement method of turbine blade speed and tip clearance based on the principle of laser self-mixing is proposed.Firstly,a self-hybrid interference model based on the three-mirror F-P cavity model is proposed,and a mathematical model of velocimetry and ranging is formulated on this basis.Then,the processing of dynamic self-mixing interference signals under the rotation of turbine blades is studied,and the collected signals are successively processed by bandpass filtering and wavelet noise reduction.FFT is used to obtain the frequency and the blade tip clearance value.After that,static and dynamic laser self-hybrid interferometric ranging experiments are implemented for verification.Finally,the error sources affecting dynamic measurement are discussed,and the measurement system and algorithm are optimized and compensated.Experimental results show that this method can effectively improve the stability and accuracy of synchronous measurement of turbine blade speed and tip clearance.The relative error of speed measurement is 1%,and the error of tip clearance measurement is 23μm.