Author(s): U. Keller; P. U. Olkart; H. E. Minor

Linked Author(s): Urs Keller

Keywords: BottomOutlet; Air-waterflow; HydraulicJump; FlowTransition; Field periments; Hydraulics Measurements

Abstract: cannot always be attained for different reasons, e.g. supplementary heightening of dams. Anwith no influence from the tail water, the paper presents a second case in which a hydraulic Common design criteria for bottom outlets stipulate free surface flow in the tailrace tunnel as sure fluctuations in a possibly pressurized air-water discharge. Nevertheless, these criteria assessed at two prototype sites and a physical model. Beginning with the common design case on the air discharge into and pressure distribution in the tailrace tunnel are discussed. jump occurs in the tailrace tunnel. Yet, in this second case still no pressurized mixture discharge into the tunnel and the related air pressure head in the gate chamber can be shown. other aspect possibly leading to flow conditions other than free surface mixture flow may be charge occurs after the hydraulic jump. Nevertheless, significant differences in the air distail water level pressurized air-water mixture discharge is imminent. Also here, consequences an unavoidable influence from the tail water. The consequences of such an influence were to avoid unpredictable conditions concerning air pressure and air discharges as well as presThe paper concludes with a third case in which after the hydraulic jump induced by a high

DOI:

Year: 2003