Moving Finite Element Simulation of Compressible Natural Gas Flow in Pipelines

摘要

The background for the present work is the need for simulation of gas flow in pipelines. The increasing exploitation of offshore oil and gas has raised a strong demand for improved calculation methods for analysis and design of pipeline systems. Reliable predictions of essential physical variables like pressure, flow rate, temperature and density are required for improving the design basis. Similarly, the operation of the pipeline could be improved and automated. Another aspect is the need for leak-control caused by the everincreasing concern about factors such as environment, safety and product-loss. The present work is concentrated on development of numerical methods for simulation of transient gas flow in pipelines with special emphasis upon resolution of fast transients such as shocks. Special numerical methods are needed for such problems. The adaptive methods are suited for these kind of problems. In this thesis we have developed a Moving Finite Element Method (MFEM) for the simulation of gas flow in pipelines. Finally Chapter 8 summarizes the results of the work with the MFEM methods, and future work is discussed. Various inner products arising from the MFEM method are given in Appendix A. Some results from the simulations performed in Chapter 5 are presented in Appendix B. Several different flow situations have been simulated, these include changes in both pressure and flow rate at the inlet and at the outlet of the pipe. The program is able to reach a steady state flow condition if the boundary conditions are kept constant. The developed ODE-solver is very robust, and the new implementation concepts have improved the efficiency. 122 refs. (ERA citation 14:010735)