Study On Characteristics Of Leaky Acoustic Wave For Fluid Transportation Pipeline

Acoustic leak detection technology has the advantage of high sensitivity, strong real-time and high accuracy of leakage location. In the field of long distance transportation pipeline leak detection, it has great value in application. Limited by the current stage of technology, the acoustic leak detection method has been practically used wildly. To break the technical barriers, this paper makes a further study in every aspect of the acoustic technology, the main contents and conclusions is as follows:(1)the main parameters of the hardware units in the leaky acoustic wave acquisition system was introduced, the form of acoustic wave in different acquisition step was described, summarized a method of designing a data acquisition system for leaky acoustic wave, analyzed the data acquisition system in the lab. The system in the laboratory has great potential in data acquisition, but incompetence for low-frequency wave;(2)the two experimental pipe facilities and the gas and water transmission flow was introduced, the experimental scheme for large diameter pipe facility was planned;(3)the filtering methods for leaky acoustic wave was studied systematically, the category, principle and core concept of classical filtering methods was introduced, the applicability of filtering leaky acoustic wave was researched, the blind source separation,on behalf of the modern filter methods, was introduced, the principle and programming algorithms was studied, the denoising effect for leaky acoustic wave was researched, a filtering system was built. The results shows the classical filtering methods cannot remove the noise signal occupied the same frequency band with leaky acoustic wave, the blind source separation methods based on the independence algorithm can separate the leaky acoustic wave from the mixed waves, the wavelet filtering method has the optimal filtering effect for experimental leaky wave.(4) The generation and transmission mechanism of leaky acoustic wave acquired in small leakage aperture ratio leak experiment was studied, the impact on leaky acoustic wave transmission caused by vale, bend and reducer was analyzed, the difference between gas and water leakage experiment was compared. The results shows that the operating condition of large diameter pipe facility is much similar with the real fluid transmission pipeline, the amplitude of leaky acoustic wave attenuates exponentially in the process of transmission, the influence distance of noise wave generated by valve is limited, both the bend and reducer have a reflect action on leaky acoustic wave, the reflected wave frequency is related to the structure dimension, the water leakage experiment is different from the gas leakage experiment, in water leakage experiment, the leak energy distribution in frequency domain is related to the leakage aperture and concentrate in lower frequency band, the amplitude of leaky acoustic wave is far larger than the gas one, the amplitude change with leakage aperture in a manner of nonlinear regularity.