Hydraulic investigation of finite crested stepped spillways

Abstract

In this paper, the hydraulic properties of the finite-crested stepped spillway (FCSS) including discharge coefficient (Cd) and the ratio of energy dissipation (EDR) were experimentally investigated. Results indicated that the Cd of the FCSS changes between 0.9 and 1.2, while the ratio of the upstream head to the length of the crest (hup/Lc) changes between 0.25 and 1.8. The hup/Lc is the main parameter affecting the Cd. The value hup/Lc equal to 0.6 is a good criterion for designing the crest of the FCSS. At this point, the Cd of FCSS is about 1.0. The performance of FCSS regarding the EDR changes between 95 and 40 percent. By increasing the discharge of flow and skimming flow formation, the performance of the FCSS related to energy dissipation is dramatically decreased. HIGHLIGHTS Based on the mentioned reports, the C_d of finite-crest weirs is more than the board and sharp-crested weirs, hence in this study, the use of it as the crest of a stepped spillway is suggested. In other words, finite-crested stepped spillways are proposed and their hydraulic properties including the C_d and their ability in energy dissipation are investigated.;

Keywords

• cascade weir
• energy dissipation
• flow measurement
• short crested weir