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

In this paper, the quartercircular 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 quartercircular 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%.