Chamani, M. R. (2000), “Air inception in skimming flow regime over stepped spillways”, International Workshop on Hydraulics of Stepped Spillways, Zurich, Switzerland, March 22-24, 61-67.
This paper provides some measurements carried out to identify the air inception location of skimming flow in a large model of a stepped spillway for two slopes. A review of investigations on chute and stepped spillways is also presented. Parameters that influence the air inception have been identified. The present observations revealed that the growth of the boundary layer is enhanced by the wake and eddies formed on the steps. It was found that the enhancement of the growth of the boundary layer and the deflection of the internal flow by steps cause an early inception of air entrainment. The location of the inception section moves downstream as the discharge increases. For specific step height, the inception section moves downstream as the discharge increases. Observation revealed that the distance of the inception point from the crest is shorter for stepped spillways as compared to chute spillways. An empirical formula for the distance of the air inception section from the crest is developed to fit the experimental data.