Case studies of fluid transients in subcooled pipe flow

Transient regimes may cause excessive water hammer, and possible column separation, slug flow, plug flow and fluid-structure interaction (FSI) in the system. Fluid transients may severely disturb operation of the piping system and damage the system components. This paper presents authors' case studies of typical transient regimes in industrial and laboratory piping systems. The first case study deals with the sudden load rejection of a Francis turbine in Pluzna HPP (Slovenia). Then the results from pressure vessel blowdown experiments at UMSICHT's (Germany) pilot plant pipework are shown. Pump start with an air pocket in the system has been investigated by WL | Delft Hydraulics (The Netherlands). The last case study concerns impact tests in a structurally unrestrained pipe at the University of Dundee (UK). The underlying theory for these cases is briefly introduced and the measurements are compared with computed results.