基于时频变换的激波风洞天平信号分析与处理

在激波风洞中开展测力试验时,测力系统在风洞流场起动瞬间会受到冲击激励,从而对天平的输出信号产生惯性干扰.天平输出信号中叠加有动态气动力信号和惯性振动信号,有可能无法直接分辨出气动力信号的规律性,信号处理结果与真实气动力之间会产生较大的误差,导致处理结果不可靠.由于模型测力天平系统结构的复杂性,在极短的有效试验时间(毫秒...

SIGNAL ANALYSIS AND PROCESSING OF SHOCK TUNNEL BALANCE BASED ON TIME-FREQUENCY TRANSFORM

Shock tunnel ground test is usually used to study the high-enthalpy aerodynamic characteristics of new hypersonic vehicles. As one of the basic researches of high-temperature aerodynamics, high-precision aerodynamic force measurement is the key technology of shock tunnel ground test. When a force test is conducted in the shock tunnel, the vibration of force measurement system is excited during the starting process of shock tunnel, which causes inertial interference to the output signal of the balance. The balance signals, with dynamic force and inertial-vibration,may not directly show regularity of the real dynamic force, resulting in a big error between the processed balance forces and the real loads, and making the results unreliable. Due to complex structure of the force measurement system, part of the high-frequency components of the balance signal(high-frequency interference caused by structural high-order modal vibration, unsteady aerodynamic load or other flow field interference) may not be fully attenuated within the extremely short-duration(millisecond level). At this time, traditional filter processing and Fourier transform may increase the error of results. In order to solve the problem of aerodynamic force measurement fast and accurately,wavelet transform and Hilbert-Huang transform are used in this study to carry out noise reduction and time-frequency transform analysis for the balance signal in a cone’s force test of shock tunnel, to effectively identify the different interference components and output reliable force results. In this paper, the time-frequency transform is applied to the signal processing of the step-load and balance output. The force results are compared and analyzed to verify the effectiveness and reliability of the current method in the data-processing of the shock tunnel test, and obtain good results. At the same time, the time-frequency processing method of signal in this study will be used in the sample data pre-processing of the shock tunnel balance intelligent research.