Hydraulic Performance of Ski-Jump-Step Energy Dissipater

Considering the limitations of unit discharge for stepped chutes, a ski-jump-step energy dissipater, which is a new type of energy dissipater, is first proposed for increasing the maximum available unit discharges. In this system, preaerations are achieved through jets generated by ski-jumps and further aerations are achieved via aeration basins. It provides fully aerated flows for the stepped chutes with large unit discharges, and the problems caused by high-speed flows like energy dissipation, cavitation, and atomization are well solved. Experimental investigations about hydraulic characteristics of the ski-jump-step energy dissipater were conducted, including the flow regimes, the principle and effectiveness of energy dissipation and the characteristics of the air entrainment and the pressure distribution. Even under conditions of large unit discharges (q=118.00m2/s on the prototype), results obtained demonstrate energy dissipation as high as 75.8% and air concentrations of at least 3.6% along the whole stepped chute. The method developed herein provides a new approach for energy dissipation in stepped chutes at large discharges.