Author(s): Ciuha Dusan; Mlacnik Jure
Linked Author(s): Jurij Mlacnik
Keywords: Stilling basin; Side beams; Hydraulic jump; Dissipation
Abstract: Low head hydraulic structures usually consist of a number of spillways positioned between side walls. Due to the available total head from the reservoir water level to the tail water level, a portion of the potential approach energy in a spillway is transformed into kinetic energy which exerts a strong influence on the dynamic flow conditions and on the erosion downstream of the structure. In order to ensure the most effective dissipation in the stilling basin, a number of solutions is already known, but under the bottom limit value of the Froude number and-in our practical case-also at too low tail water levels, such solutions have no effect. The original patented construction named “Side dissipation beam” has been designed by physical model tests in the hydraulic laboratory of the Institute of Hydraulic Research in Ljubljana. On each of the side walls of the stilling basin at least one dissipation beam is positioned longitudinally in the flow direction and protrudes from the side wall into the interior of the basin. The presented structure functions at low water heads, at very low Froude numbers and by negligible reduction of the cross-section area of the stilling basin. The purpose of this invention is to improve the dissipation efficiency on the stilling basins of the small dam of the hydropower station Vrhovo on the Sava River in Slovenia. There in the year2002 the side dissipation beams have been successfully applied in the 1st spillway. At critical discharges coinciding with lower than predicted downstream water levels they successfully stabilize the hydraulic jump inside the stilling basin. Side dissipation beams in the stilling basin ensure an effective dissipation of excess kinetic energy and thus prevents the bottom and banks of the downstream riverbed reach from extensive erosion. The side dissipation beams can be applied either at the design of new hydraulic structures or as an economically acceptable refurbishment of existing structures.
Year: 2007