自振射流喷嘴腔内压力信号分析方法的研究

Analysis methods for flow pressure signals in oscillation cavity of a self-resonating jet nozzle

喷嘴腔内流体的压力脉动与自振射流的特性密切相关,获取腔内压力信号并分析其构成对自振射流产生机理的研究具有重要意义。分别应用小波分析和希尔伯特-黄变换(HHT)对实测的腔内压力脉动信号进行对比分析,讨论了两种方法在压力信号提取和时频分析的适用性。结果表明:两种方法都能对腔内信号进行分解与重构,并能很好地提取信号的主要特征信息;HHT不存在基函数的预先选择,且经验模式分解(EMD)得到的本征模函数(IMF)分量能反映原始信号的固有特性,具有实际的物理意义;HHT可得到信号的瞬时频率,更有利于对腔内的脉动信号进行实时观测。相比于小波分析,HHT更适于自振射流压力脉动信号的分析与处理。

Flow pressure pulsation in a jet nozzle’s oscillation cavity is closely related to the characteristics of self-resonating jet.Composition analysis of the pressure signals is of importance in studying the generating mechqnism of self-resonating jet.Here,the pressure pulsation signals measured were analyzed with the wavelet analysis and Hilbert-Huang transformation （HHT）and their results were compared.The applicability of the two methods in pressure signal extraction and time-frequency analysis was discussed.The results showed that both two methods can be used in decomposing and reconstructing the signals in the cavity,the main feature information of the signals can be extracted well;there is no needs to pre-select the basic functions of HHT;the inherent characteristics of original signals can be reflected with intrinsic mode functions （IMFs）obtained from the empirical mode decomposition （EMD）,they are of practical significance;the instantaneous frequencies of the signals can be gained from HHT,they are beneficial to the real-time observation for pulsation signals in the cavity;compared with the wavelet analysis,HHT is more suitable for analyzing and processing pressure pulsation signals in oscillation cavity of self-resonating jet nozzles.