Initial Investigation of Wave Interactions During Simultaneous Valve Closures in Hydraulic Piping Systems

Abstract

The effects of interference of pressure waves in simple piping systems were studied. A freeware computer code Allievi developed at the University of Valencia was used to simulate dynamic waveforms in simple and complex networks. The tests were carried out according to three scenarios. No pressure increases significantly exceeding the Joukowsky pressure in simple cases were noticed. When the effects of the simultaneous closing of three valves located at the three pressure reservoirs with pipes of the same diameter connected at "Y" junction were tested, it was shown that wave interference (between primary and reflected waves) is influenced strongly by the length of the analyzed pipes. Additionally, when a change of diameter was assumed at the "Y" junction, secondary waves appear, which are responsible for increased pressure in this type of the system (even when the lengths of the lines are identical). Water supply pipe systems are subject to cyclical loads and wave interference of similar types even during standard operations, that’s why the understanding of this issue is crucial to effectively protect the systems from the risk of possible cracks, bursts, and leaks.