Author(s): H. Chanson

Linked Author(s):

Keywords: Stepped spillway; skimming flow; inflow conditions; inception of air entrainment; flow resistance

Abstract: Modern stepped spillways are typically designed for large discharge capacities corresponding to a skimming flow regime for which flow resistance is predominantly form drag. The writer demonstrates that the inflow conditions have some effect on the skimming flow properties. Boundary layer calculations show that the flow properties at inception of free-surface aeration are substantially different with pressurized intake. The re-analysis of experimental results highlights that the equivalent Darcy friction factor is f ∼ 0.2 in average on uncontrolled stepped chute and f ∼ 0.1 on stepped chute with pressurized intake. A simple design chart is presented to estimate the residual flow velocity, and the agreement of the calculations with experimental results is deemed satisfactory for preliminary design

DOI: https://doi.org/10.1080/00221686.2006.9521660

Year: 2006