Analysis of Cavitating and Non-Cavitating Transient Flow in Pipelines Connected by Junctions

The paper deals with the development of experimental benches designed with the aim of producing test cases of transients flow through different types of junctions both in non-cavitating and cavitating conditions. The non-cavitating test cases consist in a rapid depressurization of a reservoir to which a pipe network containing the junction is connected while in the cavitating test cases the same pipe network is discharged towards an open-air reservoir by means of an ad hoc very rapid opening valve apparatus. First of all the experimental data allowed for a deeper insight on the subject from a phenomenological point of view. Then the recorded pressure time histories have been used to validate the numerical results of a code which solves the flow by means of a 1D model suitable to describe unsteady friction and cavitating phenomena. In the code the discrete gas-cavity model (DGCM) introduced by Provoost and Wylie is integrated in the method of characteristics and the junctions are modeled using a standard constant pressure approach improved with the gas cavity model.