Acoustic emission pipeline leakage diagnosis based on time-frequency entropy of HHT

In order to detect the leakage of pipeline within tankfarm, this paper puts forward an acoustic emission pipeline leakage diagnosis technique based on time-frequency entropy of HHT, considering the instability of acoustic emission signal from the leakage of pipeline. This technique adopts Hilbert-Huang Transform to analyze the acoustic emission signal of pipe wall and then obtain the HHT spectrum of signal. The HHT time-frequency plane is divided into equal area timefrequency blocks, with the calculation method of information entropy, the information entropy of the energy contained in each time-frequency block is obtained. Then, the information entropies are compared to define whether there is leakage in pipeline. Three sets of analog signal are regarded as the simulation object to calculate the time-frequency entropy of HHT. The obtained value agrees with the theoretical analysis, which verifies the effectiveness of this technique. Simulated pipeline is used for water transportation experiment. The AE signals of pipelines with a distance of 2.0 m and 14.8 m from leakage are analyzed to determine leakage. Experimental results show that this technique can accurately detect pipeline leakage.