Numerical fluid-hammer analysis by the method of characteristics in complex piping networks

Abstract

This paper describes the method of characteristics as used to calculate fluid-hammer problems in complex piping networks. The formulation is based on the one-dimensional Navier-Stokes equation that contains the viscous term expressed as wall friction. A stepwise solution procedure is constructed from compatibility relations along characteristics and appropriate boundary conditions describing various types of pipe joints. The close agreement between the numerical result and the acoustic solution validates the boundary conditions for sudden area change based on steady-state flow conditions. A non-reflecting far-end boundary condition is devised that enables certain portions of a complex system to be analyzed. A dummy-junction boundary condition proved useful in treating systems containing long pipe sections in comparison to other pipes of the system. The numerical results obtained for the sodium-loop piping arrangement of the experimental breeder reactor II with the sodium-water reaction as the pressure disturbance are presented and discussed.