The Numerical Simulation Of Buried Gas Pipeline Leakage Based On FLUENT

Natural gas pipeline network are part of the underground pipeline network in modern cities, and the leakage accident of city natural gas pipeline occasionally occurred because of some damage reasons such as the longer service life of the natural gas pipeline in some area or the influence of geological subsidence, chemical corrosion, and municipal construction etc.. Since the buried natural gas pipelines of city are usually buried directly beneath the tundra, it is hard to discover the leakage accident, and because the explosive limit of natural gas component is very low, after a small scale leakage spreads along the soil layer which may influence in a large range, some secondary accidents like explosion and fires and so on easily happened at the gathering parts. Therefore, it is significant for the simulation study of the leakage diffusion process of the buried natural gas pipeline.The diffusion of air in the soil is different from that in the atmosphere, while the substrate that leakage air of the buried pipeline spreads at the underground part is soil which can be regarded as the porous media. Firstly, the problem and the current situation of the existed buried natural gas pipeline in the city are studied in this paper, and the safety accident characteristics caused by the pipeline leakage is listed. The author consults related references and states the current research of the air leakage diffusion theory and the diffusion numerical simulation at home and abroad. Secondly, take any buried natural gas pipeline somewhere in Harbin as the engineering background, and based on some methods such as the hydrodynamics, porous media theory, the CFD-FLUENT that computes the hydrodynamics, the component transport model and the RNG k-? turbulence model are used to establish the simulation model. By using the numerical simulation method, it is analyzed by the diffusion simulation in the soil in three aspects like the 3D concentration distribution, change of the lowest explosion limit position, and pressure distribution. Based on the above models, the author analyzes the possibly existed influence factors, and focuses on the analyzing contrast of the diffusion results for natural gas leakage in the soil with different condition such as soil porosity, environmental temperature, and layered filling construction pattern of the pipeline, as a result of which concluding the influence that each factor plays on natural gas diffusion.The FLUENT software that computes the hydromechanics is utilized in this paper, and the qualitative analysis and quantitative analysis of the air diffusion in the soil is made specific to the tiny holes leakage happened on the buried natural gas pipeline in the city. It can provide reference for the safety design of the natural gas pipeline construction, accident analysis and accident emergency as well as leakage effect scale reduction and so on.