Research On Internal Leakage Identification And Flow Prediction Method Of Gas Pipeline Ball Valve

The valve is an important safety equipment in the gas pipe network system,which plays a role in cutting off,connecting and adjusting the gas pipes in urban blocks and residential courtyards,and its tightness is very important.Internal leakage of gas pipeline valves is a serious potential safety hazard,so it is of great practical significance to carry out practical research on internal leakage detection of ball valves.In this paper,the steel ball valves of DN50 and DM100 commonly used in gas pipelines are taken as objects.By combining theoretical simulation with experimental analysis,by studying the rules of valve leakage flow field and acoustic detection mechanism,an experimental platform is set up to carry out the research work of experimental diagnosis and prediction of internal leakage flow of gas pipeline ball valves.The main research contents are as follows:1.The three-dimensional pipe valve simulation model of gas pipeline is constructed.The flow field and sound field of gas pipeline ball valve are numerically simulated by Fluent software,and the changes of pressure field,velocity field,total sound pressure level frequency spectrum and power spectral density are analyzed.The generation mechanism of sound leakage signal in ball valve and the laws of acoustic signal and energy intensity under different working conditions are obtained.It lays a theoretical foundation for the experimental process design.2.Build the testing experimental platform of gas pipeline ball valve based on acoustic emission technology,and establish the basic parameters of the device and the experimental scheme of multiple working conditions.Based on the experimental data,the relationship between the opening degree,leakage rate,pressure of ball valve and acoustic emission amplitude,total sound pressure level,RMS value and ASL value is analyzed,and the central frequency range of the internal leakage signal of ball valve and its variation with working conditions are determined.3.The relationship between the four characteristic parameters of acoustic emission detection and the leakage rate of two kinds of ball valves is studied.Through the analysis of change trend,the optimal response parameters changing with the leakage rate are judged,and a bridge is established to build the relationship between the characteristic parameters and the leakage rate.4.The valve leakage rate prediction program is constructed by MATLAB software,and the time domain energy and leakage rate are fitted by Regress function regression and neural network method.The error value between the calculated prediction result and the experimental value is optimized as the basis for judging the internal leakage of ball valves,and the field verification shows the accuracy of identifying the internal leakage of ball valves.