Effect of Simultaneous Valve Closures in Hydraulic Piping Systems

The paper investigates wave interference (between pressure waves) occurring in simple hydraulic systems. Water hammer was induced by simultaneous closure of three valves located at the reservoirs of a “Y” type hydraulic system. Numerical simulations were carried out with the help of the freeware computer package Allievi enabling the reader to replicate results in a direct manner. The influence of the following quantities has been tested: Reynolds number Re (laminar and turbulent flow), the length of the pipe arms (L1, L2, L3), the constant pipe internal diameter (Di = const.) and variable internal pipe diameters Di (D1 ≠ D2 ≠ D3). The results of the research showed how unwanted interferences between pressure waves may occur and thus increase the possibility of piping system damage. Further numerical investigations are sought in consideration of unsteady skin friction losses and viscoelastic pipe wall effects.