Transient Flow in Free-Surface, Pressurized Systems

Transients may arise in a hydraulic system such that flow conditions may alternate between free surface and submerged or pressurized behavior. Analytical considerations begin with the open-channel surge equations, and the resulting method-of-characteristics solution. The surge wave in the tunnel is described after Meyer-Peter and Favre. At the free-surface, pressurized interface, a method of solution similar to the movement of a hydraulic bore is arrived at. An experimental study is presented which describes the phenomena and gives verification to the numerical mode. As an application the Wettingen system is analyzed and shown to agree favorably with earlier results.