Design Of Experimental Platform For Leakage Detection System Of Branch Structure Fluid Network Based On Acoustic Emission

Underground compressed air and water supply pipe network of coal mines is the important guarantee for the safety production of coal mines.Due to the bad environment,the leakage of the pipe network occurs now and then.With the leakage detection problem of underground compressed air and water supply network of coal mines as the background,this thesis carries out research on the leakage detection of fluid network with branch structure.On the basis of virtual instrument PXI Express of NI Company,a set of experimental platform for leakage detection of fluid network with branch structure based on fluid acoustic emission is designed.The main work is as follows:(1)The experimental platform for leakage detection of pipe network with branch structure is established.A branch pipe network with four sections of branch pipes is built by using PP-R pipe.Each section of pipe is equipped with simulated leakage point.The air compressor is used to charge gas into the pipe network,and when the pressure in the pipe reaches a certain level,the leakage of pipe network is simulated.Acoustic emission sensors are designed with ADXL001 accelerometer chip is used to collect acoustic emission signal of the pipe network leakage,and the acquisition and processing of signal is completed through the virtual instrument PXIe(2)The key algorithms for leakage detection and location of pipe network are studied.The EEMD(Ensemble Empirical Mode Decomposition)and kurtosis is used to extract the characteristics of the signal,and a support vector machine is used to determine whether the leakage of the pipe network occured.When the pipe network leaked,the leakage pipe section is determined by comparing the signal amplitude of each sensor and de-noised by wavelet threshold,and the delay time of the signal to the two ends of the leakage pipe is obtained by cross correlation method,thus determining the location of the leakage point.(3)The leakage detection system software is designed.With LabVIEW2013 as the development platform,combined with pipe network leakage detection and location algorithm,the design of communication module,data processing module and human machine interaction module are completed,realizing the collection,processing and storage of the data,displaying the running condition of the pipe network,the leakage and the location of the leakage point in real time(4)The leakage detection system is tested by the established experimental platform,and the test data is analyzed.The results showed that the leakage detection system of the branch structure fluid pipe network have good performance with a high resolution for the leakage of the pipe network,which can realize the accurate location of the leakage point.