Study On Gas Leakage And Diffusion Law In Gas Compartment Of Integrated Pipe Gallery

In order to show the gas concentration field in the gas compartment of the integrated pipe corridor under mechanical ventilation,and to master the law of the concentration field of the leaking gas in the gas cabin,the leakage diffusion law of the gas in the gas cabin is simulated.In this paper,a CfD method is used to simulate the effect of ventilation on the leakage of gas in the gas compartment of the integrated pipe corridor,and the methane instead of the natural gas is used as the simulation object.Firstly,the numerical model of 200 m long gas cabin is established with GAMBIT2.4,and the numerical model of gas cabin is solved by fluent,and the mechanical ventilation airflow of the tube cabin is simulated with the same method,and the function of the uniform air distribution of the Tube corridor is studied.In this paper,the theory of gas pipeline leakage diffusion in gas tank is studied and analyzed,the leakage and diffusion of gas pipelines in gas tanks belong to confined jets,the compressibility factor,leakage aperture and jet density are confirmed theoretically,and the leakage coefficient formula is deduced.Gas pipeline leakage belongs to orifice flow,Leakage injection speed with the increase in pressure will not always increase,leakage reached a critical state will appear "Yong-Plug",at this time the leakage speed of sound,leakage is also reached the largest.The formula of leakage jet velocity is deduced,and the critical leakage velocity formula is obtained,and the critical leakage velocity is calculated by 165.4m/s.According to the mass conservation equation,momentum conservation equation,energy conservation equation,and component conservation equation,the influence model of ventilation in gas pipe cabin to eliminate the dilution of gas leakage is established.The influence of different ventilation quantity on the diffusion dilution of gas leakage is simulated.The influence of the gas leakage position(distance from the outlet of the vent,the direction of leaking injection),the shape of the leaking hole(round hole and longhole)on the distribution of the diffuse concentration field after the leakage in the gas cabin of the integrated pipe corridor,and the scope of the dangerous area of combustion explosion,in order to prevent the gas leakage in the beginning of the cabin to accumulate at the end of the corner,the uniform distribution of pipe corridor simulation study,the distribution fan to make the pipe corridor ventilation uniformity,so that the leakage of the pipe cabin gas can be discharged by ventilation in a timely manner outside the Tube cabin.The result of simulation shows that the closer the leakage is to the exhaust vent,the lower the concentration and diffusion range of the gas in the tube cabin,the lower the risk degree,the farther away the exhaust vent,the higher the concentration and diffusion range of the gas in the Tube cabin,the higher the risk degree;the greater the ventilation,the more obvious the dilution of the leaking gas and the less the risk;the longer the leak,The higher the gas concentration in the pipe compartment,the higher the risk;According to the simulation results after the gas leakage,the local or the entire gas tank may reach the explosion concentration range,there is the danger of explosion damage to the underground corridor,so the research of this paper puts forward to improve the standard of the pipe corridor construction,improve the timeliness and accuracy of gas alarm detection,Pipe cabin increase ventilation volume and other engineering proposals.