Transient analysis of gas flow in a straight pipe

In the present work, numerical simulation has been done to analyze transien ts in gas flow and pressure in a horizontal straight pipe. For a single gas pipeline, eight representative cases corresponding to different causes of transient behaviour are simulated to predict unsteady state flow and the ev olution of pressure profiles. The numerical results show that depending upo n the pipe dimensions and operating variables such as pressure and gas flow rate, transient effects in the pipeline may last for a long time and/or ov er significant length of pipe. The simulations predict an initial surge in gas flow rate greater than the final steady-state value if the pressure dro p across the pipe is increased. Similarly, initial flow rate may decrease b elow the final steady-state value if the pressure drop is decreased. In cas e of complete closure of a valve, oscillations in both pressure and mass fl ow rate are observed, which gradually decay and the steady state conditions of no flow are ultimately achieved. The present results are compared with a published work from the literature. A reasonably good agreement is found between these two predictions. The present study is of practical significan ce in safe design and operation of a gas delivery system.