The Study of Hydraulic Properties of Quarter-Circular Crested Stepped Spillway

In this paper, the quarter-circular crested stepped spillway (QCSS) is introduced and its hydraulic properties including the discharge coefficient (Cd) and energy dissipation of flow are investigated. The QCSS consists of a quarter-circular as the crest and a stepped chute. The Cd of QCSS variates between 0.9 and 1.4 considering the range of relative upstream head (hup/R) between 0.1 and 1.0, but at the same range of hup/R, the Cd of the broad crested stepped spillway (BCSS) changes between 0.9 and 1.0. The ratio of energy dissipation changes between 30% and 98% for both hydraulic models. Comparing the performance of QCSS and BCSS shows that in the skimming flow condition, the Cd of QCSS is about 30%more than the BCSS. Whereas, in the same flow regime, the energy dissipation of the flow on QCSS is a bit less than the BCSS about 10%.