关键词: 天然气管道 , 氮气置换 , 混气段 , 速度;暋数值模拟

Abstract: Through building the pipeline model, giving the boundary conditions and setting up the solver in Fluent software, analyze the character of mixture gas using species transport model. Through the analysis result know that the shape of the mixture gas changes from the shape of straight line to the shape of bullet as the inlet velocity increases. The concentration of nitrogen decreases with line regular pattern in the axis direction, as time goes, the diffusion range is spreading; the nitrogen replacement velocity increases with the increasing of inlet velocity, at the beginning of the replacement, the increasing rate of the mixture length is faster than latter. The replacement length increases as time goes, the faster the replacement velocity the higher increasing ratio of the replacement length, and the replacement efficiency is increasing as the inlet velocity increases, but the ratio is decreasing.

Key words: Natural gas pipeline,    ,  Nitrogen replacement,    ,  Mixture gas,    ,  Velocity,    ,  Numerical simulation