The focus of this paper is on investigating the flow development and decay in a single closed loop, under pump start up as well as trip conditions. The relevant governing differential equations are derived from first principles. A numerical solution technique is described for integration of these equations that uses data from the complete pump characteristic curves. A step by step solution algorithm is provided for the same. Benchmarking and validation studies against available numerical and experimental data are presented. Thereafter, the solution technique is demonstrated using actual performance curves of several pumps. Finally, parametric studies are presented to highlight the influence of specific speed on the flow development and decay in the closed loop.

Keywords: Transient, coastdown, startup, closed loop, pump characteristic curves