Closed Conduit to Open Channel Stilling Basin

Criteria have been developed for designing a stilling basin to serve as a transition from closed conduit flow to open channel flow for a fully submerged pipe outlet. The unique feature of the stilling basin is the short-pipe energy dissipater so located and designed as to provide maximum energy dissipation for the basin configuration. The expanding characteristics of a submerged jet were used in establishing the length of the stilling basin. The unsteadiness of the water surface and the relative boil height in the model basin were used as the criteria for evaluating the effectiveness of the structure for energy dissipation. Relations between the tailwater depth, the outlet flume floor elevation, the height of boils in the stilling basin, the width of the stilling basin, and the amount of freeboard have been studied. The interrelationships among these variables have been shown graphically.