Investigation on effect of Discharge, spillway's slope and step's characteristics on the Ogee-stepped spillway on energy dissipation by applying numerical models

Stepped spillway's are one of hydraulic components of dams that made by straight step's near the spillway's crest to the toe to dissipate energy. In this study to simulate the flow over the stepped spillway, Flow3D software that is analytic flow field was used. The k-ε(RNG) model was the turbulence model which had been applied, and to determine the free surface flow profiles VOF model was used. The skimming flow regime was only considered. For this purpose 112 spillway models was designed that from which, 96 models were stepped models and 16 models were smooth models. Stepped models had six configurations, two step sizes and four different slopes (15degrees, 30degrees, 45degrees and 60degrees) below the contact points and also step edges were followed WES profile. Smooth spillways had also corresponding specifications for the slope and crest profiles. The goal of this study was investigating on the effects of discharge, spillway's slope, number of steps, configuration and steps roughness on energy dissipation. It was observed that discharge flowing over the spillway and slope of spillway were among the most effective parameters to achieve the highest energy dissipation on stepped spillways and in higher discharges, the number of steps and its configurations had less effects. Also a mentioned configuration considering the parameters to reach the maximum energy dissipation was introduced.