Numerical Simulation of the Transient Flow in Natural Gas Transmission Lines Using a Computational Fluid Dynamic Method

Abstract

Until now, almost all tools that are used to analyze gas transportation networks are based on steady flow conditions. Some design problems can be solved by the assumption of a steady state. However, some circumstances force us to use transient analyses, which commonly include changes in customer demand, the failure of a compressor station or gas pipeline ruptures. In this study, the dynamic behavior of natural gas in transmission lines was investigated through Computational Fluid Dynamic (CFD) simulations. The system was modeled using the equations of continuity, motion (or momentum), energy and the ideal gas equation when considering turbulence effects in a two dimensional cylindrical lattice. The coupled partial differential equations were discretized based on the finite volume method. The accuracy of this method was verified by comparing the experimental field data with this approach, showing errors of approximately 4 to 4.5%, which shows the precision of this approach. Finally, an important case study was used as an application for the model and the best possible operating solution was proposed for a compressor station failure during peak demand times when the pipelines were operating at the maximum flow rate.