The elevated tank is located more than 70 m above the city of Salzburg. In case of malfunctions or when emptying the tank, up to 380 l/s must be discharged via this height into the on-site preflooder without causing damage. There is a risk that an unstable water-air mixture will occur and damage the facilty.
In order to exclude this danger and to achieve optimal flow conditions, the institute was commissioned to carry out a physical model. The result of this study was a design which forces the formation of a water vortex. The spiral-shaped flow along the pipe wall leaves an air core in the center of the pipe and thus creates stable and safe discharge conditions in the drop shaft and in the outlet channel. The system was successfully commissioned in 1992.
Drop shaft in the physical model at a discharge of 200 l/s
Drop shaft in the physical model at a discharge of 380 l/s
View of the drop shaft from above