Numerical Simulation Of Indoor Natural Gas Pipeline Leakage And Diffusion Based On FLUENT

With the development of technology and the transformation of energy,natural gas has become the necessities of our residents'life,and its sufficient reserves and low price have been welcomed and loved by people.However,with the popularization of indoor natural gas application,the risk of natural gas as a combustible dangerous substance arises at the same time.In recent years,the most difficult to control and frequent accidents are the fire and explosion events caused by the leakage of domestic gas,which endangers the safety of Chinese people's property and increases the difficulty of natural gas promotion and national energy structure transformation.Therefore,this paper studies the leakage and diffusion characteristics of indoor natural gas pipeline by means of computational fluid dynamics,which provides theoretical support for the promotion and utilization of clean energy such as natural gas and hazard prediction.First of all,according to the characteristics of indoor natural gas leakage and diffusion,considering the compressibility of mixed gas,according to the theory of gas turbulent jet in fluid mechanics,three leakage models are established,including small hole model,pipe model and large hole model.At the same time,based on the RNG k-?turbulence model,using the specifications component module,considering the multi-component diffusion efficiency in the research process,and with the energy conversion,two numerical calculation models of natural gas plane leakage diffusion and natural gas double leakage diffusion coupling are established.Secondly,the jet process and the coupling process of double leakage flow field of natural gas under transient condition are studied.The change trend of CH₄concentration field,density field and velocity field at different diffusion time is analyzed.The development law of leakage diffusion process and the coupling characteristics of double leakage flow field are revealed.The research shows that the leakage and diffusion of natural gas is a typical flow field jet process.With the continuous development of natural gas diffusion process,the core area,the starting section and the main section of the jet field are formed,forming a"gradually shrinking"form of high concentration CH₄distribution.At the same time,when the distance between the two leaks is relatively close,the coupling effect of the two is strong at the early stage of the leak,and the stronger one has the entrainment effect on the weaker one,which changes the basic form of the jet flow field.Finally,the influence of different leakage parameters,such as leakage volume,leakage mode and leakage pressure,and boundary parameters,such as different wind speed and outlet pressure,on the leakage diffusion characteristics are analyzed.The results show that the increase of leakage inlet speed will promote the development of diffusion field,reduce the time required for the diffusion field to reach the stable stage,and increase the core development area.The choice of different leakage modes greatly affects the distribution of gas leakage dispersion field.With the increase of the leakage pressure,the turbulent kinetic energy of the jet at the leakage port is increased,and the overall energy is promoted to meet the development demand of the jet flow field.With the increase of the ratio of wind speed to leakage speed,the outside expansion angle decreases gradually,and the jet field deflection tends to accelerate.The increase of the outlet pressure can restrain the development of the plane leakage jet flow field.