气体管道泄漏声发射单一非频散模态定位

针对气体管道泄漏声发射信号的多模态、频散特性导致互相关泄漏定位误差大的问题,提出采用单一非频散模态提取的气体管道泄漏声发射定位方法。对检测信号的互谱加窗,并根据模态波数确定窗参数,可获得泄漏声发射信号的单一非频散模态导波的互谱。对单一非频散模态导波的互谱进行傅里叶反变换,得到泄漏声发射中单一非频散模态信号的互相关函数以及时延估计,就可以采用单一非频散模态声速,更准确计算出泄漏位置。对气体管道泄漏进行定位实验,相比用未经分解的泄漏声发射信号进行定位,由于声发射单一非频散模态信号的相关性增强,且选用的声速更准确,定位相对误差平均降低7%以上。这表明,通过提取泄漏信号互谱的单一非频散模态成分进行时延估计,可以提高泄漏检测的有效性和减小定位误差。

Leak location in gas pipelines by extraction of single non dispersive mode from leakage induced acoustic emission signal

The correlation based leak location errors are large due to the multi modal and dispersive characteristics of leakage induced acoustic emission. One kind of leak location in the gas pipelines by extracting the single non dispersive mode is proposed in this study. The cross power spectrum of the single modal and non dispersive component in the leak acoustic emission can be obtained by applying the weighing window with parameters of the wave number of the relative mode. Then, the cross power spectrum of a single modal and non dispersive component is analyzed by the inverse Fourier transformed to acquire the cross correlation for estimating the time delay. Hence, the acoustic velocity of a single modal and non dispersive component can be used for calculating the leak position more accurately. The experiments of leak location indicate that the relative error is reduced at least 7%. The reason is the enhancement of correlativity of a single modal and non dispersive component in leak acoustic emission and the adoption of a more accurate acoustic velocity. It shows that the time delay estimation by extracting the single modal and non dispersive component in the cross power spectrum of leakage induced acoustic emission signals will enhance the leak detection and location.