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对管道泄漏声发射信号进行传播特性研究,可以为工程上进行传感器布设和采集参数确定提供参考依据。介质类型、压力、流量与泄漏孔径对产生的泄漏声发射信号幅值影响较大,对泄漏声发射信号传播衰减规律无影响。泄漏介质为气体时,产生的声发射信号幅值较大;随着压力的增加,泄漏声发射信号幅值增大;随着泄漏孔径的增大,泄漏声发射信号幅值先变大后变小。应用FFT变换和小波包分解等理论方法,分析泄漏声发射信号在传播过程中经过法兰、阀门时的频率变化特征。研究结果表明:泄漏声发射信号经过法兰后,主要引起信号幅值衰减,衰减值为11~15 dB,而信号频率分布变化不大。泄漏声发射信号经过阀门后不仅信号幅值衰减27~35 dB,且信号的高频成分(187.5~312.5 kHz)也出现较大幅度的衰减。
Propagating characteristics of acoustic emission signal from pipeline leak can provide a reference for engineering sensor layout and parameters acquisition. Media type, pressure, flow rate and leakage aperture have a great influence on the amplitude of acoustic emission signal leakage, and have no effect on the propagation attenuation law of leakage acoustic emission signal. When the leakage medium is a gas, the amplitude of the acoustic emission signal is large; as the pressure increases, the amplitude of the acoustic emission signal of the leakage increases; as the leakage aperture increases, the amplitude of the acoustic emission signal of the leakage first becomes large and then changes small. Applying the theory of FFT transform and wavelet packet decomposition, the frequency characteristics of leakage acoustic emission signal passing through flange and valve during propagation are analyzed. The results show that the leaked acoustic emission signal mainly causes the signal amplitude attenuation after passing through the flange, the attenuation value is 11-15 dB, while the signal frequency distribution has little change. The leakage acoustic emission signal not only attenuates the signal amplitude by 27-35 dB after passing through the valve, but also attenuates the high frequency component (187.5-312.5 kHz) of the signal greatly.