GAS-DYNAMIC PROCESSES OCCURRING DURING THE DESTRUCTION OF GAS PIPELINES AND METHODS OF THEIR ANALYSIS

Abstract

The process of dynamic destruction of a typical section of a steel main gas pipeline with a crack under the action of gas dynamic pressure is considered. The high-speed development of a crack, which grows under the action of a large amount of gas flowing out under high pressure, is investigated. The process of the main crack movement, which is induced by the gas movement, is modeled. The mathematical model of this process includes a model of gas-dynamic processes in a pipe and a model of high-speed deformation and fracture of a pipe section with a crack. An approximate analytical model of gas-dynamic processes is proposed, which makes it possible to simulate the dynamic decrease in pressure on the inner surface of the pipe and the crack bank. The dynamic pressure change is based on decompression of gas in the localized part of the pipe in the vicinity of the crack. The model takes into account the change in gas pressure in the pipeline along the longitudinal coordinate of the part of the pipe with a crack. A numerical procedure for calculating the gas dynamic pressure when gas flows through a crack is considered. It allows you to determine the pressure on the crack banks as a function of time. The results of this numerical procedure are used for numerical simulation of high-speed deformation and avalanche destruction of a typical section of a main gas pipeline with a crack. An analytical model is proposed that uses the methods of fracture mechanics to predict the critical pressure at which crack growth in the pipe is observed. The model is verified according to experimental data and serves for a quick assessment of the integrity of the pipe. This analytical approach is used to predict the possibility of pipe failure based on material properties, crack geometry and pipe dimensions. It can be used for preliminary estimation calculations. A numerical-analytical method for the analysis of inelastic dynamic destruction of a pipe is considered. It is based on the analysis of the magnitude of the crack tip opening angle. A numerical method for analyzing the stress state in the crack region, taking into account plastic deformation, is also considered. The presented models allow numerical methods to investigate the dynamics of crack development and, as a consequence, the destruction of typical sections of main gas pipelines under pressure. Using the results of these studies will make it possible to take preventive measures to prevent cases of avalanche destruction of emergency sections of main pipelines.