Numerical modeling of transient turbulent gas flow in a pipe following a rupture

Abstract

The transient flow of a compressible gas generated in a pipeline after an accidental rupture is studied numerically. The numerical simulation is performed by solving the conservation equations of an axisymmetric, transient, viscous, subsonic flow in a circular pipe including the breakpoint. The numerical technique is a combined finite element-finite volume method applied on the unstructured grid. A modified K - ε model with a two-layer equation for the near wall region and compressibility correction is used to predict the turbulent viscosity. The results show that, for example, after a time period of 0.16 seconds, the pressure at a distance of 61.5 m upstream of the breakpoint reduces about 8%, while this value for the downstream pressure located at the same distance from the rupture is about 14% at the same time. Also, the mass flow rate released from the rupture point will reach 2.4 times its initial value and become constant when the sonic condition occurs at this point after 0.16 seconds. Also the average pressure of the rupture reduced to 60% of its initial value and remained constant at the same time and under the same condition. The results are compared with available experimental and numerical studies for steady compressible pipe flow. © Sharif University of Technology, April 2010.