基于小波变换的补燃循环火箭发动机模态参数辨识

The modal parameters identification of the staged combustion rocket engine based on wavelet transform

文中阐述基于小波变换的结构模态参数辨识方法的基本原理。首先介绍Heisenberg测不准原理,该原理限制了时频能量的同时集中。因小波变换的窗口可以随信号特征不同而变化,符合实际信号的要求。然后论述利用小波脊线的方法识别单自由度和多自由度系统的模态参数的理论。将该方法应用于某型补燃循环液体火箭发动机模态参数辨识中,得到了误差小于3%的前7阶固有频率,并且利用Hilbert变换的方法验证该发动机具有线性系统的特征。小波变换法无需采用复杂的激振设备,只使用响应信号,避免功率泄露和频率混叠等因素的影响。而且该方法可以应用到液体火箭发动机工作环境下的识别。

This paper expounds the principle of the structural modal parameter identification based on the wavelet transform.First it introduces the Heisenberg uncertainty principle.The principle limits the same concentration of time and frequency energy.However,the window of the wavelet transform can vary with the signal characteristics.Therefore,it is consistent with the requirements of the actual signal.Then the paper describes the theory of wavelet ridge identifying the single-degree-of-freedom and multi-degree-of-freedom systems.And it is applied to the modal parameters identification of the staged combustion cycle rocket engine.The first 7 natural frequencies,the errors of which are less than 3% are obtained.And the paper uses the Hilbert transform to verify that the engine has the characteristic of linear systems.The wavelet transform doesn＇t need to use the complex excitation equipment,only uses the response signal.So it can avoid the power leakage,frequency aliasing and other unfavorable factors.Besides,it can be used for the engine parameters identification in the working environment.