Downstream hydraulic transients in combined free-surface, pressurized flow pipelines

The purpose of this research was to evaluate hydraulic transients in a combined free-surface, pressurized flow system with free-surface supercritical flow. This research focused on cases in which hydraulic transients are generated from the movement of a valve in the pressurized region of the system. A numerical model was developed to predict the hydraulic transients and the model was applied to simulate the hydraulic transients in a water transmission pipeline. The numerical model uses the Method of Characteristics for pressurized flow and supercritical, open-channel hydraulics to simulate the free-surface flow. Hydraulic transients in free-surface flow were not modeled as part of this research. Data analysis on hydraulic transient propagation and interaction with the pressurized/free-surface transition are presented.