基于ITD和STD的液体火箭发动机模态参数辨识方法

ITD and STD based identification for modal parameters of liquid rocket engine

在液体火箭发动机模态参数辨识领域,频域法仍是模态分析的主流方法,但该方法存在诸如功率泄露、频率混叠和离线分析等不足。本研究将基于时域识别的ITD法和STD法应用到液体火箭发动机模态参数辨识领域。由于这两种算法的基础是线性系统,利用Hilbert变换的方法,验证该发动机具有线性系统特征。与频域法对比的结果表明,该方法具有较高识别精度,且只使用实测响应信号,使用设备简单,因而可以在线分析,为发动机在工作环境下的参数识别奠定了基础。

In the field of the modal parameters identification of the liquid rocket engine, the tre- quency domain method is widely used. But this method has some shortcomings, such as power reveal, frequency mixture and off-line analysis. In this research, the ITD and STD methods based on time-do- main identification were applied to this field. Since the two algorithms are based on the linear system, the l-Iilbert transform is used in this paper to verify that the engine has the characteristic of the linear systems. Compared with the frequency-domain method, the results show that the method has higher recognition accuracy, uses the measured response signals only, needs more simple equipments in the identification, and can conduct the online analysis. Thus it laid a foundation for the engine parameters identification in the working environment.