A Research On Gas Leak Localization Of Pressure Vessels Based On Ultrasonic Guided Waves

In recent years,the gas pressure vessels are widely used in the national production.At the same time,with the development of the special application environment,such as the manned spacecraft in orbit,the stable and efficient operation of the pressure vessels is becoming more and more important.The gas leakage is one of the main factors threatening the normal operation condition of the pressure vessels.When the leakage occurs,it will cause the structural damage,bring huge economic losses and even threat the personal safety and cause irreparable consequences.Therefore,in order to ensure the safe operation of the system,a real-time leak detection system is needed to locate the leakage source quickly and accurately.This paper uses the ultrasonic guided waves in the wall structure of the pressure vessels to locate the leakage source and studies the acoustic source localization method based on ultrasonic guided waves.The feasibility of the leakage localization method is validated by the leakage localization experiment.The main contents of this paper are summarized as follows:Based on the gas leakage experimental platform,the time-frequency characteristics and the cross correlation characteristics of the leakage signal are analyzed.Through the finite element simulation analysis and experimental analysis of laser Doppler vibrometer,the propagation characteristics of leakage signals in the structure are studied.The dispersion curves of ultrasonic guided waves and the phenomenon of the reflection at the boundary of the structure are experimentally measured.The effect of stiffener structure on ultrasonic guided waves is studied,and the attenuation coefficient caused by the stiffener is obtained,which lays the foundation for using the ultrasonic guided waves to locate leakage source.Considering the effect of the multi modes and dispersion of the guided waves on the leakage location,a new method of acoustic source localization based on wave number domain is proposed.The leakage signals collected by the ultrasonic sensor array are transformed into the wave number domain,and the direction of the leakage source is estimated in the intensity distribution map of the wave number field.The experimental results show that the method is not affected by multi modes and dispersion,and the location of the leakage source is realized.Because the complex implementation and weak anti-interference ability of the leakage localization method based on the wavenumber domain,this paper proposes an alternative localization method based on the improved beamforming algorithm.The dispersion curve is introduced in the sum-and-delay beamforming algorithm to compensate the effect of dispersion to the leakage localization.The experimental results show that the positioning method is stable and reliable on both flat plate and stiffened plate.