Pipeline start-up with entrapped air

Abstract

A mathematical model for the assessment of the pressure head maxima that air pockets within a pipeline can originate on start-up is presented. This model is based on a general model addressing the filling of a pipeline with several air pockets published by the authors. Here the simulation of the operation of a discharge valve in order to control the peak pressure following the pump start-up is included. Also, in order to correctly model reverse flow through the pump use is made of the dimensionless Suter curves. Water movement is modelled through rigid column theory and air - water straight cross section moving interfaces are considered. Because of the huge pressure values that the very rapid compression of the air can cause, and in order to avoid pipe breaks, practical engineers must lend great attention to this problem.