Natural Gas Pipeline Leakage And Diffusion And Explosion Numerical Simulation Study

With the development of natural gas pipeline industry, more and more people tend to use natural gas. During the natural gas gathering and transportation process, leakage may occur for strictness seal, erosion and artificial maladministration. After natural gas diffusing into the atmosphere, mixing with air and forming inflammable premix gasses, it is likely to initiate fire or explosion if meet ignition sources; Even if the fire or explosion doesn't occur, the leaking natural gas and its concomitant will still stay at atmosphere, this will have a bad effect on human health and environment for a long time in the future. So that the leakage of natural gas will not only result in the lost of energy source material, cause huge economic loss, but also cause malignancy accident ,such as fire, explosion, poisoning, and so on. Therefore, to carry out numerical simulation study on natural gas pipeline leakage, diffusion and explosion will mean a lot to transportation security and life and property safety.This paper bases on hydromechanics, thermodynamics, explosion mechanics, computational mathematics and computer technology, researches on the methods of the diffusion and explosion instance after natural gas leakage, analyses rules of diffusion and explosion. Firstly, this paper analyses the research status of gas leakage, diffusion and explosion in domestic and abroad, studies the leakage rate , turbulent jet theory and extension mechanism of explosion of natural gas pipeline, deduces the basic equation of gas flowing. Secondly, bases on the hydromechanics and thermodynamics elementary theory, this paper establishes a mathematical model of natural gas diffusion after leaking into atmosphere, applies finite element method to solve the partial differential equation group in the model. Thirdly, analyses the influencing factors of explosion, according to hydromechanics, thermodynamics and explosion theory, builds natural gas line explosion standard K-epsilon turbulence model, corrects K-epsilon by using RNG method, confirms relevant boundary conditions, applies finite volume method to solve turbulence explosion model. Ultimately, bases on above-mentioned models, adopts computational fluid mechanics simulation software-FLUENT to simulate the natural gas leakage, diffusion and explosion.On the basis of research results, analyses the process of natural gas leakage and explosion separately. According to the leakage and diffusion, this paper analyses high-velocity jet and low speed leakage instances: For the high-velocity jet, analyses natural diffusion without influencing factors and diffusion instances impacted by different wind speed, delivery pressure, impediments; For the low speed leakage, analyses natural diffusion without influencing factors and diffusion instances impacted by wind speed, temperature, impediments, leakage location, terrain, gravitation. According to explosion caused by fire, analyses the high-speed jet catching fire situation impacted by wind speed.The analysis shows, the natural gas leakage will form turbulent jet. After density and speed reducing, it begins to diffuse into the atmosphere; every factor will increase the hazard ness after leaking and diffusion. Among those factors,the leaking velocity (spillage) , wind speed, impediment and the terrain have greater effect on the natural gas diffusion. When the natural gas meets ignition source during high-velocity jet, it will burn because the speed is too high to explode. Consider the influencing factors of the diffusion and explosion, we can control or man-made changing some factors to reduce its risk. Thereby the poisoning, explosion accident could be effectively prevented.The research results of natural gas leakage diffusion and explosion numerical simulation in this paper coincides with the fire and explosion theory very well. Thereby the correctness of theoretical analysis in this paper is proved. The research method provides a new clue for the natural gas leakage diffusion and explosion theoretical research. The discipline gained from analysis has certain guidance significances and reference value for the natural gas line's transportation safety and maintenance.