Modeling propagation of pressure surges with the formation of an air pocket in pipelines

In this study, a computational model that combines the method of characteristics and the shock wave theory is developed to simulate the propagation of pressure surges in pipelines. The surge velocity and pressure change under the conditions of pressurization and depressurization are calculated. The model results show good agreement with measured data. The transient flow model is also extended to study the movement of an entrapped air pocket between interfaces. It is found the air pressure changes greatly during the early stage of formation of an air pocket. For the case of an air pocket trapped between two positive interfaces, an open surge front may be emerged from the upstream interface and eventually reverses the upstream surge to propagate upstream as a negative wave. (C) 2002 Elsevier Science Ltd. All rights reserved.