Localization Algorithm Of Gas Leakage Source Based On Ultrasonic Virtual Phased Array

Gas leak detection is one of the important research directions in the field of industrial non-destructive testing,which has important theoretical significance and economic value.In order to solve the problem that conventional arrays have insufficient angular resolution due to the limited aperture of the array,which cannot be used for gas leak imaging positioning,a virtual array-based beamforming technology is proposed to enable imaging gas leak detection and positioning.In this thesis,the traditional array signal model and the virtual array signal model are discussed first.The virtual array collects gas leakage signals through time-sharing scanning.In this study,the reference sensor and the scanning sensor are introduced to work at the same time,and the scanning interval is eliminated by calculating the crosspower spectrum of the reference signal and the scanning signal.Using a virtual array to collect leak signals can break through the traditional array formation fixation and the limited array aperture,laying a hardware foundation for imaging leak detection.Then,the CBF algorithm,MVDR algorithm and RCB algorithm based on virtual arrays are studied.Through simulation experiments,the effects of various factors on the positioning method performance are simulated,compared and discussed,including the number of sensors and the spacing between adjacent sensors in the array.Simulation results show that the number of array elements should be large enough to maintain positioning accuracy,and the distance of half wavelength should be set to the distance between adjacent array elements to avoid false peak interference and improve positioning resolution.The positioning performance of each algorithm under the same conditions is also compared through simulation,and the advantages and disadvantages of each algorithm are compared.Finally,through actual gas leak experiments,the imaging gas leak detection and localization performance of different algorithms are compared.In the laboratory environment,all three algorithms can obtain good positioning results,and the imaging gas leakage positioning results obtained are simple and intuitive,which is conducive to the operator's early detection and early treatment.Then,in order to evaluate the stability and accuracy of the proposed method,15 experiments were performed under the same experimental conditions.Then,in order to evaluate the stability and accuracy of the proposed method,15 experiments were performed under the same experimental conditions.The results show that the gas phase leak detection method based on virtual phased array can obtain gas leak positioning results with high accuracy and good stability.